revised pda patches

From: Jeremy Fitzhardinge
Date: Tue Sep 26 2006 - 03:11:01 EST

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Hi Andi,

Here's an updated series of PDA patches based on your tree. They're intended to replace these:

i386-pda-basics
i386-pda-init-pda
i386-pda-use-gs
i386-pda-user-abi
i386-pda-vm86
i386-pda-smp-processorid
i386-pda-current

with these:

i386-pda-definitions.patch
i386-pda-init.patch
i386-pda-use-gs.patch
i386-pda-fix-abi.patch
i386-pda-fix-vm86.patch
i386-pda-smp_processor_id.patch
i386-pda-current.patch

Thanks,
J
Basic definitions for i386-pda

This patch has the basic definitions of struct i386_pda, and the
segment selector in the GDT.

asm-i386/pda.h is more or less a direct copy of asm-x86_64/pda.h. The
most interesting difference is the use of _proxy_pda, which is used to
give gcc a model for the actual memory operations on the real pda
structure. No actual reference is ever made to _proxy_pda, so it is
never defined.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>
Cc: Chuck Ebbert <76306.1226@xxxxxxxxxxxxxx>
Cc: Zachary Amsden <zach@xxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxx>

---
arch/i386/kernel/asm-offsets.c | 4 +
arch/i386/kernel/head.S | 2
include/asm-i386/pda.h | 86 ++++++++++++++++++++++++++++++++++++++++
include/asm-i386/segment.h | 5 +-
4 files changed, 95 insertions(+), 2 deletions(-)

diff -r 0a6d1e9953f7 arch/i386/kernel/asm-offsets.c
--- a/arch/i386/kernel/asm-offsets.c Mon Sep 25 15:41:31 2006 -0700
+++ b/arch/i386/kernel/asm-offsets.c Mon Sep 25 22:36:23 2006 -0700
@@ -15,6 +15,7 @@
#include <asm/processor.h>
#include <asm/thread_info.h>
#include <asm/elf.h>
+#include <asm/pda.h>

#define DEFINE(sym, val) \
asm volatile("\n->" #sym " %0 " #val : : "i" (val))
@@ -91,4 +92,7 @@ void foo(void)
DEFINE(VDSO_PRELINK, VDSO_PRELINK);

OFFSET(crypto_tfm_ctx_offset, crypto_tfm, __crt_ctx);
+
+ BLANK();
+ OFFSET(PDA_pcurrent, i386_pda, pcurrent);
}
diff -r 0a6d1e9953f7 arch/i386/kernel/head.S
--- a/arch/i386/kernel/head.S Mon Sep 25 15:41:31 2006 -0700
+++ b/arch/i386/kernel/head.S Mon Sep 25 22:36:23 2006 -0700
@@ -518,7 +518,7 @@ ENTRY(cpu_gdt_table)
.quad 0x004092000000ffff /* 0xc8 APM DS data */

.quad 0x0000920000000000 /* 0xd0 - ESPFIX 16-bit SS */
- .quad 0x0000000000000000 /* 0xd8 - unused */
+ .quad 0x0000000000000000 /* 0xd8 - PDA */
.quad 0x0000000000000000 /* 0xe0 - unused */
.quad 0x0000000000000000 /* 0xe8 - unused */
.quad 0x0000000000000000 /* 0xf0 - unused */
diff -r 0a6d1e9953f7 include/asm-i386/pda.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-i386/pda.h Mon Sep 25 22:40:32 2006 -0700
@@ -0,0 +1,98 @@
+/*
+ Per-processor Data Areas
+ Jeremy Fitzhardinge <jeremy@xxxxxxxx> 2006
+ Based on asm-x86_64/pda.h by Andi Kleen.
+ */
+#ifndef _I386_PDA_H
+#define _I386_PDA_H
+
+#include <linux/stddef.h>
+
+struct i386_pda
+{
+ struct i386_pda *_pda; /* pointer to self */
+
+ struct task_struct *pcurrent; /* current process */
+ int cpu_number;
+};
+
+extern struct i386_pda *_cpu_pda[];
+
+#define cpu_pda(i) (_cpu_pda[i])
+
+#define pda_offset(field) offsetof(struct i386_pda, field)
+
+extern void __bad_pda_field(void);
+
+/* This variable is never instantiated. It is only used as a stand-in
+ for the real per-cpu PDA memory, so that gcc can understand what
+ memory operations the inline asms() below are performing. This
+ eliminates the need to make the asms volatile or have memory
+ clobbers, so gcc can readily analyse them. */
+extern struct i386_pda _proxy_pda;
+
+#define pda_to_op(op,field,val) \
+ do { \
+ typedef typeof(_proxy_pda.field) T__; \
+ if (0) { T__ tmp__; tmp__ = (val); } \
+ switch (sizeof(_proxy_pda.field)) { \
+ case 1: \
+ asm(op "b %1,%%gs:%c2" \
+ : "+m" (_proxy_pda.field) \
+ :"ri" ((T__)val), \
+ "i"(pda_offset(field))); \
+ break; \
+ case 2: \
+ asm(op "w %1,%%gs:%c2" \
+ : "+m" (_proxy_pda.field) \
+ :"ri" ((T__)val), \
+ "i"(pda_offset(field))); \
+ break; \
+ case 4: \
+ asm(op "l %1,%%gs:%c2" \
+ : "+m" (_proxy_pda.field) \
+ :"ri" ((T__)val), \
+ "i"(pda_offset(field))); \
+ break; \
+ default: __bad_pda_field(); \
+ } \
+ } while (0)
+
+#define pda_from_op(op,field) \
+ ({ \
+ typeof(_proxy_pda.field) ret__; \
+ switch (sizeof(_proxy_pda.field)) { \
+ case 1: \
+ asm(op "b %%gs:%c1,%0" \
+ : "=r" (ret__) \
+ : "i" (pda_offset(field)), \
+ "m" (_proxy_pda.field)); \
+ break; \
+ case 2: \
+ asm(op "w %%gs:%c1,%0" \
+ : "=r" (ret__) \
+ : "i" (pda_offset(field)), \
+ "m" (_proxy_pda.field)); \
+ break; \
+ case 4: \
+ asm(op "l %%gs:%c1,%0" \
+ : "=r" (ret__) \
+ : "i" (pda_offset(field)), \
+ "m" (_proxy_pda.field)); \
+ break; \
+ default: __bad_pda_field(); \
+ } \
+ ret__; })
+
+/* Return a pointer to a pda field */
+#define pda_addr(field) \
+ ((typeof(_proxy_pda.field) *)((unsigned char *)read_pda(_pda) + \
+ pda_offset(field)))
+
+#define read_pda(field) pda_from_op("mov",field)
+#define write_pda(field,val) pda_to_op("mov",field,val)
+#define add_pda(field,val) pda_to_op("add",field,val)
+#define sub_pda(field,val) pda_to_op("sub",field,val)
+#define or_pda(field,val) pda_to_op("or",field,val)
+
+#endif /* _I386_PDA_H */
diff -r 0a6d1e9953f7 include/asm-i386/segment.h
--- a/include/asm-i386/segment.h Mon Sep 25 15:41:31 2006 -0700
+++ b/include/asm-i386/segment.h Mon Sep 25 15:41:36 2006 -0700
@@ -39,7 +39,7 @@
* 25 - APM BIOS support
*
* 26 - ESPFIX small SS
- * 27 - unused
+ * 27 - PDA [ per-cpu private data area ]
* 28 - unused
* 29 - unused
* 30 - unused
@@ -73,6 +73,9 @@

#define GDT_ENTRY_ESPFIX_SS (GDT_ENTRY_KERNEL_BASE + 14)
#define __ESPFIX_SS (GDT_ENTRY_ESPFIX_SS * 8)
+
+#define GDT_ENTRY_PDA (GDT_ENTRY_KERNEL_BASE + 15)
+#define __KERNEL_PDA (GDT_ENTRY_PDA * 8)

#define GDT_ENTRY_DOUBLEFAULT_TSS 31

Initialize the per-CPU data area.

When a CPU is brought up, a PDA and GDT are allocated for it. The
GDT's __KERNEL_PDA entry is pointed to the allocated PDA memory, so
that all references using this segment descriptor will refer to the PDA.

This patch rearranges CPU initialization a bit, so that the GDT/PDA
are set up as early as possible in cpu_init(). Also for secondary
CPUs, GDT+PDA are preallocated and initialized so all the secondary
CPU needs to do is set up the ldt and load %gs. This will be
important once smp_processor_id() and current use the PDA.

In all cases, the PDA is set up in head.S, before a CPU starts running
C code, so the PDA is always available.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>
Cc: Chuck Ebbert <76306.1226@xxxxxxxxxxxxxx>
Cc: Zachary Amsden <zach@xxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxx>
Cc: James Bottomley <James.Bottomley@xxxxxxxxxxxx>
Cc: Matt Tolentino <matthew.e.tolentino@xxxxxxxxx>

---
arch/i386/kernel/cpu/common.c | 293 +++++++++++++++++++++++++++--------------
arch/i386/kernel/smpboot.c | 31 +++-
include/asm-i386/pda.h | 20 ++
include/asm-i386/processor.h | 3
4 files changed, 239 insertions(+), 108 deletions(-)

diff -r 575ec0ce9e80 arch/i386/kernel/cpu/common.c
--- a/arch/i386/kernel/cpu/common.c Mon Sep 25 23:29:45 2006 -0700
+++ b/arch/i386/kernel/cpu/common.c Mon Sep 25 23:30:45 2006 -0700
@@ -18,6 +18,7 @@
#include <asm/apic.h>
#include <mach_apic.h>
#endif
+#include <asm/pda.h>

#include "cpu.h"

@@ -26,6 +27,9 @@ EXPORT_PER_CPU_SYMBOL(cpu_gdt_descr);

DEFINE_PER_CPU(unsigned char, cpu_16bit_stack[CPU_16BIT_STACK_SIZE]);
EXPORT_PER_CPU_SYMBOL(cpu_16bit_stack);
+
+struct i386_pda *_cpu_pda[NR_CPUS] __read_mostly;
+EXPORT_SYMBOL(_cpu_pda);

static int cachesize_override __cpuinitdata = -1;
static int disable_x86_fxsr __cpuinitdata;
@@ -582,6 +586,184 @@ void __init early_cpu_init(void)
disable_pse = 1;
#endif
}
+
+__cpuinit int alloc_gdt(int cpu)
+{
+ struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu);
+ struct desc_struct *gdt;
+ struct i386_pda *pda;
+
+ gdt = (struct desc_struct *)cpu_gdt_descr->address;
+ pda = cpu_pda(cpu);
+
+ /*
+ * This is a horrible hack to allocate the GDT. The problem
+ * is that cpu_init() is called really early for the boot CPU
+ * (and hence needs bootmem) but much later for the secondary
+ * CPUs, when bootmem will have gone away
+ */
+ if (NODE_DATA(0)->bdata->node_bootmem_map) {
+ BUG_ON(gdt != NULL || pda != NULL);
+
+ gdt = alloc_bootmem_pages(PAGE_SIZE);
+ pda = alloc_bootmem(sizeof(*pda));
+ /* alloc_bootmem(_pages) panics on failure, so no check */
+
+ memset(gdt, 0, PAGE_SIZE);
+ memset(pda, 0, sizeof(*pda));
+ } else {
+ /* GDT and PDA might already have been allocated if
+ this is a CPU hotplug re-insertion. */
+ if (gdt == NULL)
+ gdt = (struct desc_struct *)get_zeroed_page(GFP_KERNEL);
+
+ if (pda == NULL)
+ pda = kmalloc_node(sizeof(*pda), GFP_KERNEL, cpu_to_node(cpu));
+
+ if (unlikely(!gdt || !pda)) {
+ free_pages((unsigned long)gdt, 0);
+ kfree(pda);
+ return 0;
+ }
+ }
+
+ cpu_gdt_descr->address = (unsigned long)gdt;
+ cpu_pda(cpu) = pda;
+
+ return 1;
+}
+
+/* Initial PDA used by boot CPU */
+struct i386_pda boot_pda = {
+ ._pda = &boot_pda,
+ .cpu_number = 0,
+ .pcurrent = &init_task,
+};
+
+/* Initialize the CPU's GDT and PDA. The boot CPU does this for
+ itself, but secondaries find this done for them. */
+__cpuinit int init_gdt(int cpu, struct task_struct *idle)
+{
+ struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu);
+ __u32 stk16_off = (__u32)&per_cpu(cpu_16bit_stack, cpu);
+ struct desc_struct *gdt;
+ struct i386_pda *pda;
+
+ /* For non-boot CPUs, the GDT and PDA should already have been
+ allocated. */
+ if (!alloc_gdt(cpu)) {
+ printk(KERN_CRIT "CPU%d failed to allocate GDT or PDA\n", cpu);
+ return 0;
+ }
+
+ gdt = (struct desc_struct *)cpu_gdt_descr->address;
+ pda = cpu_pda(cpu);
+
+ BUG_ON(gdt == NULL || pda == NULL);
+
+ /*
+ * Initialize the per-CPU GDT with the boot GDT,
+ * and set up the GDT descriptor:
+ */
+ memcpy(gdt, cpu_gdt_table, GDT_SIZE);
+ cpu_gdt_descr->size = GDT_SIZE - 1;
+
+ /* Set up GDT entry for 16bit stack */
+ *(__u64 *)(&gdt[GDT_ENTRY_ESPFIX_SS]) |=
+ ((((__u64)stk16_off) << 16) & 0x000000ffffff0000ULL) |
+ ((((__u64)stk16_off) << 32) & 0xff00000000000000ULL) |
+ (CPU_16BIT_STACK_SIZE - 1);
+
+ pack_descriptor((u32 *)&gdt[GDT_ENTRY_PDA].a,
+ (u32 *)&gdt[GDT_ENTRY_PDA].b,
+ (unsigned long)pda, sizeof(*pda) - 1,
+ 0x80 | DESCTYPE_S | 0x2, 0); /* present read-write data segment */
+
+ memset(pda, 0, sizeof(*pda));
+ pda->_pda = pda;
+ pda->cpu_number = cpu;
+ pda->pcurrent = idle;
+
+ return 1;
+}
+
+/* Common CPU init for both boot and secondary CPUs */
+static void __cpuinit _cpu_init(int cpu, struct task_struct *curr)
+{
+ struct tss_struct * t = &per_cpu(init_tss, cpu);
+ struct thread_struct *thread = &curr->thread;
+ struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu);
+
+ /* Reinit these anyway, even if they've already been done (on
+ the boot CPU, this will transition from the boot gdt+pda to
+ the real ones). */
+ load_gdt(cpu_gdt_descr);
+
+ if (cpu_test_and_set(cpu, cpu_initialized)) {
+ printk(KERN_WARNING "CPU#%d already initialized!\n", cpu);
+ for (;;) local_irq_enable();
+ }
+
+ printk(KERN_INFO "Initializing CPU#%d\n", cpu);
+
+ if (cpu_has_vme || cpu_has_tsc || cpu_has_de)
+ clear_in_cr4(X86_CR4_VME|X86_CR4_PVI|X86_CR4_TSD|X86_CR4_DE);
+ if (tsc_disable && cpu_has_tsc) {
+ printk(KERN_NOTICE "Disabling TSC...\n");
+ /**** FIX-HPA: DOES THIS REALLY BELONG HERE? ****/
+ clear_bit(X86_FEATURE_TSC, boot_cpu_data.x86_capability);
+ set_in_cr4(X86_CR4_TSD);
+ }
+
+ load_idt(&idt_descr);
+
+ /*
+ * Set up and load the per-CPU TSS and LDT
+ */
+ atomic_inc(&init_mm.mm_count);
+ curr->active_mm = &init_mm;
+ if (curr->mm)
+ BUG();
+ enter_lazy_tlb(&init_mm, curr);
+
+ load_esp0(t, thread);
+ set_tss_desc(cpu,t);
+ load_TR_desc();
+ load_LDT(&init_mm.context);
+
+#ifdef CONFIG_DOUBLEFAULT
+ /* Set up doublefault TSS pointer in the GDT */
+ __set_tss_desc(cpu, GDT_ENTRY_DOUBLEFAULT_TSS, &doublefault_tss);
+#endif
+
+ /* Clear %fs and %gs. */
+ asm volatile ("movl %0, %%fs; movl %0, %%gs" : : "r" (0));
+
+ /* Clear all 6 debug registers: */
+ set_debugreg(0, 0);
+ set_debugreg(0, 1);
+ set_debugreg(0, 2);
+ set_debugreg(0, 3);
+ set_debugreg(0, 6);
+ set_debugreg(0, 7);
+
+ /*
+ * Force FPU initialization:
+ */
+ current_thread_info()->status = 0;
+ clear_used_math();
+ mxcsr_feature_mask_init();
+}
+
+/* Entrypoint to initialize secondary CPU */
+void __cpuinit secondary_cpu_init(void)
+{
+ int cpu = smp_processor_id();
+ struct task_struct *curr = current;
+
+ _cpu_init(cpu, curr);
+}
+
/*
* cpu_init() initializes state that is per-CPU. Some data is already
* initialized (naturally) in the bootstrap process, such as the GDT
@@ -591,106 +773,17 @@ void __cpuinit cpu_init(void)
void __cpuinit cpu_init(void)
{
int cpu = smp_processor_id();
- struct tss_struct * t = &per_cpu(init_tss, cpu);
- struct thread_struct *thread = &current->thread;
- struct desc_struct *gdt;
- __u32 stk16_off = (__u32)&per_cpu(cpu_16bit_stack, cpu);
- struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu);
-
- if (cpu_test_and_set(cpu, cpu_initialized)) {
- printk(KERN_WARNING "CPU#%d already initialized!\n", cpu);
- for (;;) local_irq_enable();
- }
- printk(KERN_INFO "Initializing CPU#%d\n", cpu);
-
- if (cpu_has_vme || cpu_has_tsc || cpu_has_de)
- clear_in_cr4(X86_CR4_VME|X86_CR4_PVI|X86_CR4_TSD|X86_CR4_DE);
- if (tsc_disable && cpu_has_tsc) {
- printk(KERN_NOTICE "Disabling TSC...\n");
- /**** FIX-HPA: DOES THIS REALLY BELONG HERE? ****/
- clear_bit(X86_FEATURE_TSC, boot_cpu_data.x86_capability);
- set_in_cr4(X86_CR4_TSD);
- }
-
- /* The CPU hotplug case */
- if (cpu_gdt_descr->address) {
- gdt = (struct desc_struct *)cpu_gdt_descr->address;
- memset(gdt, 0, PAGE_SIZE);
- goto old_gdt;
- }
- /*
- * This is a horrible hack to allocate the GDT. The problem
- * is that cpu_init() is called really early for the boot CPU
- * (and hence needs bootmem) but much later for the secondary
- * CPUs, when bootmem will have gone away
- */
- if (NODE_DATA(0)->bdata->node_bootmem_map) {
- gdt = (struct desc_struct *)alloc_bootmem_pages(PAGE_SIZE);
- /* alloc_bootmem_pages panics on failure, so no check */
- memset(gdt, 0, PAGE_SIZE);
- } else {
- gdt = (struct desc_struct *)get_zeroed_page(GFP_KERNEL);
- if (unlikely(!gdt)) {
- printk(KERN_CRIT "CPU%d failed to allocate GDT\n", cpu);
- for (;;)
- local_irq_enable();
- }
- }
-old_gdt:
- /*
- * Initialize the per-CPU GDT with the boot GDT,
- * and set up the GDT descriptor:
- */
- memcpy(gdt, cpu_gdt_table, GDT_SIZE);
-
- /* Set up GDT entry for 16bit stack */
- *(__u64 *)(&gdt[GDT_ENTRY_ESPFIX_SS]) |=
- ((((__u64)stk16_off) << 16) & 0x000000ffffff0000ULL) |
- ((((__u64)stk16_off) << 32) & 0xff00000000000000ULL) |
- (CPU_16BIT_STACK_SIZE - 1);
-
- cpu_gdt_descr->size = GDT_SIZE - 1;
- cpu_gdt_descr->address = (unsigned long)gdt;
-
- load_gdt(cpu_gdt_descr);
- load_idt(&idt_descr);
-
- /*
- * Set up and load the per-CPU TSS and LDT
- */
- atomic_inc(&init_mm.mm_count);
- current->active_mm = &init_mm;
- if (current->mm)
- BUG();
- enter_lazy_tlb(&init_mm, current);
-
- load_esp0(t, thread);
- set_tss_desc(cpu,t);
- load_TR_desc();
- load_LDT(&init_mm.context);
-
-#ifdef CONFIG_DOUBLEFAULT
- /* Set up doublefault TSS pointer in the GDT */
- __set_tss_desc(cpu, GDT_ENTRY_DOUBLEFAULT_TSS, &doublefault_tss);
-#endif
-
- /* Clear %fs and %gs. */
- asm volatile ("movl %0, %%fs; movl %0, %%gs" : : "r" (0));
-
- /* Clear all 6 debug registers: */
- set_debugreg(0, 0);
- set_debugreg(0, 1);
- set_debugreg(0, 2);
- set_debugreg(0, 3);
- set_debugreg(0, 6);
- set_debugreg(0, 7);
-
- /*
- * Force FPU initialization:
- */
- current_thread_info()->status = 0;
- clear_used_math();
- mxcsr_feature_mask_init();
+ struct task_struct *curr = current;
+
+ /* Set up the real GDT and PDA, so we can transition from the
+ boot versions. */
+ if (!init_gdt(cpu, curr)) {
+ /* failed to allocate something; not much we can do... */
+ for (;;)
+ local_irq_enable();
+ }
+
+ _cpu_init(cpu, curr);
}

#ifdef CONFIG_HOTPLUG_CPU
diff -r 575ec0ce9e80 arch/i386/kernel/smpboot.c
--- a/arch/i386/kernel/smpboot.c Mon Sep 25 23:29:45 2006 -0700
+++ b/arch/i386/kernel/smpboot.c Mon Sep 25 23:29:47 2006 -0700
@@ -534,11 +534,11 @@ static void __devinit start_secondary(vo
static void __devinit start_secondary(void *unused)
{
/*
- * Dont put anything before smp_callin(), SMP
+ * Don't put *anything* before secondary_cpu_init(), SMP
* booting is too fragile that we want to limit the
* things done here to the most necessary things.
*/
- cpu_init();
+ secondary_cpu_init();
preempt_disable();
smp_callin();
while (!cpu_isset(smp_processor_id(), smp_commenced_mask))
@@ -597,13 +597,16 @@ void __devinit initialize_secondary(void
"movl %0,%%esp\n\t"
"jmp *%1"
:
- :"r" (current->thread.esp),"r" (current->thread.eip));
-}
-
+ :"m" (current->thread.esp),"m" (current->thread.eip));
+}
+
+/* Static state in head.S used to set up a CPU */
extern struct {
void * esp;
unsigned short ss;
} stack_start;
+extern struct i386_pda *start_pda;
+extern struct Xgt_desc_struct cpu_gdt_descr;

#ifdef CONFIG_NUMA

@@ -929,9 +932,6 @@ static int __devinit do_boot_cpu(int api
unsigned long start_eip;
unsigned short nmi_high = 0, nmi_low = 0;

- ++cpucount;
- alternatives_smp_switch(1);
-
/*
* We can't use kernel_thread since we must avoid to
* reschedule the child.
@@ -939,14 +939,29 @@ static int __devinit do_boot_cpu(int api
idle = alloc_idle_task(cpu);
if (IS_ERR(idle))
panic("failed fork for CPU %d", cpu);
+
+ /* Pre-allocate and initialize the CPU's GDT and PDA so it
+ doesn't have to do any memory allocation during the
+ delicate CPU-bringup phase. */
+ if (!init_gdt(cpu, idle)) {
+ printk(KERN_INFO "Couldn't allocate GDT/PDA for CPU %d\n", cpu);
+ return -1; /* ? */
+ }
+
idle->thread.eip = (unsigned long) start_secondary;
/* start_eip had better be page-aligned! */
start_eip = setup_trampoline();
+
+ ++cpucount;
+ alternatives_smp_switch(1);

/* So we see what's up */
printk("Booting processor %d/%d eip %lx\n", cpu, apicid, start_eip);
/* Stack for startup_32 can be just as for start_secondary onwards */
stack_start.esp = (void *) idle->thread.esp;
+
+ start_pda = cpu_pda(cpu);
+ cpu_gdt_descr = per_cpu(cpu_gdt_descr, cpu);

irq_ctx_init(cpu);

diff -r 575ec0ce9e80 include/asm-i386/processor.h
--- a/include/asm-i386/processor.h Mon Sep 25 23:29:45 2006 -0700
+++ b/include/asm-i386/processor.h Mon Sep 25 23:29:47 2006 -0700
@@ -731,4 +731,7 @@ extern void enable_sep_cpu(void);
extern void enable_sep_cpu(void);
extern int sysenter_setup(void);

+extern int init_gdt(int cpu, struct task_struct *idle);
+extern void secondary_cpu_init(void);
+
#endif /* __ASM_I386_PROCESSOR_H */
Use %gs as the PDA base-segment in the kernel.

This patch is the meat of the PDA change. This patch makes several
related changes:

1: Most significantly, %gs is now used in the kernel. This means that on
entry, the old value of %gs is saved away, and it is reloaded with
__KERNEL_PDA.

2: entry.S constructs the stack in the shape of struct pt_regs, and this
is passed around the kernel so that the process's saved register
state can be accessed.

Unfortunately struct pt_regs doesn't currently have space for %gs
(or %fs). This patch extends pt_regs to add space for gs (no space
is allocated for %fs, since it won't be used, and it would just
complicate the code in entry.S to work around the space).

3: Because %gs is now saved on the stack like %ds, %es and the integer
registers, there are a number of places where it no longer needs to
be handled specially; namely context switch, and saving/restoring the
register state in a signal context.

4: And since kernel threads run in kernel space and call normal kernel
code, they need to be created with their %gs == __KERNEL_PDA.

NOTE: even though it's called "ptrace-abi.h", this file does not
define a user-space visible ABI.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>
Cc: Chuck Ebbert <76306.1226@xxxxxxxxxxxxxx>
Cc: Zachary Amsden <zach@xxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxx>

---
arch/i386/kernel/asm-offsets.c | 1
arch/i386/kernel/cpu/common.c | 21 +++++++++-
arch/i386/kernel/entry.S | 81 +++++++++++++++++++++++-----------------
arch/i386/kernel/head.S | 33 +++++++++++++---
arch/i386/kernel/process.c | 27 ++++++-------
arch/i386/kernel/signal.c | 6 --
include/asm-i386/mmu_context.h | 4 -
include/asm-i386/processor.h | 4 +
include/asm-i386/ptrace.h | 2
kernel/fork.c | 2
10 files changed, 119 insertions(+), 62 deletions(-)

diff -r 1b8b053ad03f arch/i386/kernel/asm-offsets.c
--- a/arch/i386/kernel/asm-offsets.c Mon Sep 25 23:31:01 2006 -0700
+++ b/arch/i386/kernel/asm-offsets.c Mon Sep 25 23:31:04 2006 -0700
@@ -68,6 +68,7 @@ void foo(void)
OFFSET(PT_EAX, pt_regs, eax);
OFFSET(PT_DS, pt_regs, xds);
OFFSET(PT_ES, pt_regs, xes);
+ OFFSET(PT_GS, pt_regs, xgs);
OFFSET(PT_ORIG_EAX, pt_regs, orig_eax);
OFFSET(PT_EIP, pt_regs, eip);
OFFSET(PT_CS, pt_regs, xcs);
diff -r 1b8b053ad03f arch/i386/kernel/cpu/common.c
--- a/arch/i386/kernel/cpu/common.c Mon Sep 25 23:31:01 2006 -0700
+++ b/arch/i386/kernel/cpu/common.c Mon Sep 25 23:31:04 2006 -0700
@@ -587,6 +587,14 @@ void __init early_cpu_init(void)
#endif
}

+/* Make sure %gs is initialized properly in idle threads */
+struct pt_regs * __devinit idle_regs(struct pt_regs *regs)
+{
+ memset(regs, 0, sizeof(struct pt_regs));
+ regs->xgs = __KERNEL_PDA;
+ return regs;
+}
+
__cpuinit int alloc_gdt(int cpu)
{
struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu);
@@ -640,6 +648,14 @@ struct i386_pda boot_pda = {
.pcurrent = &init_task,
};

+static inline void set_kernel_gs(void)
+{
+ /* Set %gs for this CPU's PDA. Memory clobber is to create a
+ barrier with respect to any PDA operations, so the compiler
+ doesn't move any before here. */
+ asm volatile ("mov %0, %%gs" : : "r" (__KERNEL_PDA) : "memory");
+}
+
/* Initialize the CPU's GDT and PDA. The boot CPU does this for
itself, but secondaries find this done for them. */
__cpuinit int init_gdt(int cpu, struct task_struct *idle)
@@ -698,6 +714,7 @@ static void __cpuinit _cpu_init(int cpu,
the boot CPU, this will transition from the boot gdt+pda to
the real ones). */
load_gdt(cpu_gdt_descr);
+ set_kernel_gs();

if (cpu_test_and_set(cpu, cpu_initialized)) {
printk(KERN_WARNING "CPU#%d already initialized!\n", cpu);
@@ -736,8 +753,8 @@ static void __cpuinit _cpu_init(int cpu,
__set_tss_desc(cpu, GDT_ENTRY_DOUBLEFAULT_TSS, &doublefault_tss);
#endif

- /* Clear %fs and %gs. */
- asm volatile ("movl %0, %%fs; movl %0, %%gs" : : "r" (0));
+ /* Clear %fs. */
+ asm volatile ("mov %0, %%fs" : : "r" (0));

/* Clear all 6 debug registers: */
set_debugreg(0, 0);
diff -r 1b8b053ad03f arch/i386/kernel/entry.S
--- a/arch/i386/kernel/entry.S Mon Sep 25 23:31:01 2006 -0700
+++ b/arch/i386/kernel/entry.S Mon Sep 25 23:32:16 2006 -0700
@@ -30,12 +30,13 @@
* 18(%esp) - %eax
* 1C(%esp) - %ds
* 20(%esp) - %es
- * 24(%esp) - orig_eax
- * 28(%esp) - %eip
- * 2C(%esp) - %cs
- * 30(%esp) - %eflags
- * 34(%esp) - %oldesp
- * 38(%esp) - %oldss
+ * 24(%esp) - %gs
+ * 28(%esp) - orig_eax
+ * 2C(%esp) - %eip
+ * 30(%esp) - %cs
+ * 34(%esp) - %eflags
+ * 38(%esp) - %oldesp
+ * 3C(%esp) - %oldss
*
* "current" is in register %ebx during any slow entries.
*/
@@ -91,6 +92,9 @@ 1:

#define SAVE_ALL \
cld; \
+ pushl %gs; \
+ CFI_ADJUST_CFA_OFFSET 4;\
+ /*CFI_REL_OFFSET gs, 0;*/\
pushl %es; \
CFI_ADJUST_CFA_OFFSET 4;\
/*CFI_REL_OFFSET es, 0;*/\
@@ -120,8 +124,10 @@ 1:
CFI_REL_OFFSET ebx, 0;\
movl $(__USER_DS), %edx; \
movl %edx, %ds; \
- movl %edx, %es;
-
+ movl %edx, %es; \
+ movl $(__KERNEL_PDA), %edx; \
+ movl %edx, %gs
+
#define RESTORE_INT_REGS \
popl %ebx; \
CFI_ADJUST_CFA_OFFSET -4;\
@@ -153,17 +159,22 @@ 2: popl %es; \
2: popl %es; \
CFI_ADJUST_CFA_OFFSET -4;\
/*CFI_RESTORE es;*/\
-.section .fixup,"ax"; \
-3: movl $0,(%esp); \
+3: popl %gs; \
+ CFI_ADJUST_CFA_OFFSET -4;\
+ /*CFI_RESTORE gs;*/\
+.pushsection .fixup,"ax"; \
+4: movl $0,(%esp); \
jmp 1b; \
-4: movl $0,(%esp); \
+5: movl $0,(%esp); \
jmp 2b; \
-.previous; \
+6: movl $0,(%esp); \
+ jmp 3b; \
.section __ex_table,"a";\
.align 4; \
- .long 1b,3b; \
- .long 2b,4b; \
-.previous
+ .long 1b,4b; \
+ .long 2b,5b; \
+ .long 3b,6b; \
+.popsection

#define RING0_INT_FRAME \
CFI_STARTPROC simple;\
@@ -321,10 +332,17 @@ 1: movl (%ebp),%ebp
movl PT_EIP(%esp), %edx
movl PT_OLDESP(%esp), %ecx
xorl %ebp,%ebp
+1: mov PT_GS(%esp), %gs
TRACE_IRQS_ON
ENABLE_INTERRUPTS_SYSEXIT
CFI_ENDPROC
-
+.pushsection .fixup,"ax"
+2: movl $0,PT_GS(%esp)
+ jmp 1b
+.section __ex_table,"a"
+ .align 4
+ .long 1b,2b
+.popsection

# system call handler stub
ENTRY(system_call)
@@ -370,7 +388,7 @@ restore_nocheck:
TRACE_IRQS_IRET
restore_nocheck_notrace:
RESTORE_REGS
- addl $4, %esp
+ addl $4, %esp # skip orig_eax/error_code
CFI_ADJUST_CFA_OFFSET -4
1: INTERRUPT_RETURN
.section .fixup,"ax"
@@ -512,14 +530,12 @@ syscall_badsys:
/* put ESP to the proper location */ \
movl %eax, %esp;
#define UNWIND_ESPFIX_STACK \
- pushl %eax; \
CFI_ADJUST_CFA_OFFSET 4; \
movl %ss, %eax; \
/* see if on 16bit stack */ \
- cmpw $__ESPFIX_SS, %ax; \
+ cmp $__ESPFIX_SS, %eax; \
je 28f; \
-27: popl %eax; \
- CFI_ADJUST_CFA_OFFSET -4; \
+27: CFI_ADJUST_CFA_OFFSET -4; \
.section .fixup,"ax"; \
28: movl $__KERNEL_DS, %eax; \
movl %eax, %ds; \
@@ -588,13 +604,15 @@ KPROBE_ENTRY(page_fault)
CFI_ADJUST_CFA_OFFSET 4
ALIGN
error_code:
+ /* the function address is in %gs's slot on the stack */
+ pushl %es
+ CFI_ADJUST_CFA_OFFSET 4
pushl %ds
CFI_ADJUST_CFA_OFFSET 4
/*CFI_REL_OFFSET ds, 0*/
pushl %eax
CFI_ADJUST_CFA_OFFSET 4
CFI_REL_OFFSET eax, 0
- xorl %eax, %eax
pushl %ebp
CFI_ADJUST_CFA_OFFSET 4
CFI_REL_OFFSET ebp, 0
@@ -607,7 +625,6 @@ error_code:
pushl %edx
CFI_ADJUST_CFA_OFFSET 4
CFI_REL_OFFSET edx, 0
- decl %eax # eax = -1
pushl %ecx
CFI_ADJUST_CFA_OFFSET 4
CFI_REL_OFFSET ecx, 0
@@ -615,21 +632,17 @@ error_code:
CFI_ADJUST_CFA_OFFSET 4
CFI_REL_OFFSET ebx, 0
cld
- pushl %es
- CFI_ADJUST_CFA_OFFSET 4
- /*CFI_REL_OFFSET es, 0*/
UNWIND_ESPFIX_STACK
- popl %ecx
- CFI_ADJUST_CFA_OFFSET -4
- /*CFI_REGISTER es, ecx*/
- movl PT_ES(%esp), %edi # get the function address
+ movl PT_GS(%esp), %edi # get the function address
movl PT_ORIG_EAX(%esp), %edx # get the error code
- movl %eax, PT_ORIG_EAX(%esp)
- movl %ecx, PT_ES(%esp)
- /*CFI_REL_OFFSET es, ES*/
+ movl $-1, PT_ORIG_EAX(%esp) # no syscall to restart
+ mov %gs, PT_GS(%esp)
+ /*CFI_REL_OFFSET gs, GS*/
movl $(__USER_DS), %ecx
movl %ecx, %ds
movl %ecx, %es
+ movl $(__KERNEL_PDA), %ecx
+ movl %ecx, %gs
movl %esp,%eax # pt_regs pointer
call *%edi
jmp ret_from_exception
@@ -939,6 +952,7 @@ ENTRY(arch_unwind_init_running)
movl %ebx, PT_EAX(%edx)
movl $__USER_DS, PT_DS(%edx)
movl $__USER_DS, PT_ES(%edx)
+ movl $0, PT_GS(%edx)
movl %ebx, PT_ORIG_EAX(%edx)
movl %ecx, PT_EIP(%edx)
movl 12(%esp), %ecx
diff -r 1b8b053ad03f arch/i386/kernel/head.S
--- a/arch/i386/kernel/head.S Mon Sep 25 23:31:01 2006 -0700
+++ b/arch/i386/kernel/head.S Mon Sep 25 23:31:04 2006 -0700
@@ -302,6 +302,7 @@ 2: movl %cr0,%eax
movl %eax,%cr0

call check_x87
+ call setup_pda
lgdt cpu_gdt_descr
lidt idt_descr
ljmp $(__KERNEL_CS),$1f
@@ -312,10 +313,13 @@ 1: movl $(__KERNEL_DS),%eax # reload all
movl %eax,%ds
movl %eax,%es

- xorl %eax,%eax # Clear FS/GS and LDT
+ xorl %eax,%eax # Clear FS and LDT
movl %eax,%fs
- movl %eax,%gs
lldt %ax
+
+ movl $(__KERNEL_PDA),%eax
+ mov %eax,%gs
+
cld # gcc2 wants the direction flag cleared at all times
pushl %eax # fake return address
#ifdef CONFIG_SMP
@@ -345,6 +349,23 @@ 1: movb $1,X86_HARD_MATH
.byte 0xDB,0xE4 /* fsetpm for 287, ignored by 387 */
ret

+/*
+ * Point the GDT at this CPU's PDA. On boot this will be
+ * cpu_gdt_table and boot_pda; for secondary CPUs, these will be
+ * that CPU's GDT and PDA.
+ */
+setup_pda:
+ /* get the PDA pointer */
+ movl start_pda, %eax
+
+ /* slot the PDA address into the GDT */
+ mov cpu_gdt_descr+2, %ecx
+ mov %ax, (__KERNEL_PDA+0+2)(%ecx) /* base & 0x0000ffff */
+ shr $16, %eax
+ mov %al, (__KERNEL_PDA+4+0)(%ecx) /* base & 0x00ff0000 */
+ mov %ah, (__KERNEL_PDA+4+3)(%ecx) /* base & 0xff000000 */
+ ret
+
/*
* setup_idt
*
@@ -424,7 +445,9 @@ ENTRY(empty_zero_page)
* This starts the data section.
*/
.data
-
+ENTRY(start_pda)
+ .long boot_pda
+
ENTRY(stack_start)
.long init_thread_union+THREAD_SIZE
.long __BOOT_DS
@@ -458,7 +481,7 @@ idt_descr:

# boot GDT descriptor (later on used by CPU#0):
.word 0 # 32 bit align gdt_desc.address
-cpu_gdt_descr:
+ENTRY(cpu_gdt_descr)
.word GDT_ENTRIES*8-1
.long cpu_gdt_table

@@ -518,7 +541,7 @@ ENTRY(cpu_gdt_table)
.quad 0x004092000000ffff /* 0xc8 APM DS data */

.quad 0x0000920000000000 /* 0xd0 - ESPFIX 16-bit SS */
- .quad 0x0000000000000000 /* 0xd8 - PDA */
+ .quad 0x00cf92000000ffff /* 0xd8 - PDA */
.quad 0x0000000000000000 /* 0xe0 - unused */
.quad 0x0000000000000000 /* 0xe8 - unused */
.quad 0x0000000000000000 /* 0xf0 - unused */
diff -r 1b8b053ad03f arch/i386/kernel/process.c
--- a/arch/i386/kernel/process.c Mon Sep 25 23:31:01 2006 -0700
+++ b/arch/i386/kernel/process.c Mon Sep 25 23:31:04 2006 -0700
@@ -56,6 +56,7 @@

#include <asm/tlbflush.h>
#include <asm/cpu.h>
+#include <asm/pda.h>

asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");

@@ -336,6 +337,7 @@ int kernel_thread(int (*fn)(void *), voi

regs.xds = __USER_DS;
regs.xes = __USER_DS;
+ regs.xgs = __KERNEL_PDA;
regs.orig_eax = -1;
regs.eip = (unsigned long) kernel_thread_helper;
regs.xcs = __KERNEL_CS | get_kernel_rpl();
@@ -421,7 +423,6 @@ int copy_thread(int nr, unsigned long cl
p->thread.eip = (unsigned long) ret_from_fork;

savesegment(fs,p->thread.fs);
- savesegment(gs,p->thread.gs);

tsk = current;
if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) {
@@ -645,16 +646,16 @@ struct task_struct fastcall * __switch_t
load_esp0(tss, next);

/*
- * Save away %fs and %gs. No need to save %es and %ds, as
- * those are always kernel segments while inside the kernel.
- * Doing this before setting the new TLS descriptors avoids
- * the situation where we temporarily have non-reloadable
- * segments in %fs and %gs. This could be an issue if the
- * NMI handler ever used %fs or %gs (it does not today), or
- * if the kernel is running inside of a hypervisor layer.
+ * Save away %fs. No need to save %gs, as it was saved on the
+ * stack on entry. No need to save %es and %ds, as those are
+ * always kernel segments while inside the kernel. Doing this
+ * before setting the new TLS descriptors avoids the situation
+ * where we temporarily have non-reloadable segments in %fs
+ * and %gs. This could be an issue if the NMI handler ever
+ * used %fs or %gs (it does not today), or if the kernel is
+ * running inside of a hypervisor layer.
*/
savesegment(fs, prev->fs);
- savesegment(gs, prev->gs);

/*
* Load the per-thread Thread-Local Storage descriptor.
@@ -662,16 +663,14 @@ struct task_struct fastcall * __switch_t
load_TLS(next, cpu);

/*
- * Restore %fs and %gs if needed.
+ * Restore %fs if needed.
*
- * Glibc normally makes %fs be zero, and %gs is one of
- * the TLS segments.
+ * Glibc normally makes %fs be zero.
*/
if (unlikely(prev->fs | next->fs))
loadsegment(fs, next->fs);

- if (prev->gs | next->gs)
- loadsegment(gs, next->gs);
+ write_pda(pcurrent, next_p);

/*
* Restore IOPL if needed.
diff -r 1b8b053ad03f arch/i386/kernel/signal.c
--- a/arch/i386/kernel/signal.c Mon Sep 25 23:31:01 2006 -0700
+++ b/arch/i386/kernel/signal.c Mon Sep 25 23:31:04 2006 -0700
@@ -128,7 +128,7 @@ restore_sigcontext(struct pt_regs *regs,
X86_EFLAGS_TF | X86_EFLAGS_SF | X86_EFLAGS_ZF | \
X86_EFLAGS_AF | X86_EFLAGS_PF | X86_EFLAGS_CF)

- GET_SEG(gs);
+ COPY_SEG(gs);
GET_SEG(fs);
COPY_SEG(es);
COPY_SEG(ds);
@@ -244,9 +244,7 @@ setup_sigcontext(struct sigcontext __use
{
int tmp, err = 0;

- tmp = 0;
- savesegment(gs, tmp);
- err |= __put_user(tmp, (unsigned int __user *)&sc->gs);
+ err |= __put_user(regs->xgs, (unsigned int __user *)&sc->gs);
savesegment(fs, tmp);
err |= __put_user(tmp, (unsigned int __user *)&sc->fs);

diff -r 1b8b053ad03f include/asm-i386/mmu_context.h
--- a/include/asm-i386/mmu_context.h Mon Sep 25 23:31:01 2006 -0700
+++ b/include/asm-i386/mmu_context.h Mon Sep 25 23:31:04 2006 -0700
@@ -62,8 +62,8 @@ static inline void switch_mm(struct mm_s
#endif
}

-#define deactivate_mm(tsk, mm) \
- asm("movl %0,%%fs ; movl %0,%%gs": :"r" (0))
+#define deactivate_mm(tsk, mm) \
+ asm("movl %0,%%fs": :"r" (0));

#define activate_mm(prev, next) \
switch_mm((prev),(next),NULL)
diff -r 1b8b053ad03f include/asm-i386/processor.h
--- a/include/asm-i386/processor.h Mon Sep 25 23:31:01 2006 -0700
+++ b/include/asm-i386/processor.h Mon Sep 25 23:31:04 2006 -0700
@@ -477,6 +477,7 @@ struct thread_struct {
.vm86_info = NULL, \
.sysenter_cs = __KERNEL_CS, \
.io_bitmap_ptr = NULL, \
+ .gs = __KERNEL_PDA, \
}

/*
@@ -504,7 +505,8 @@ static inline void load_esp0(struct tss_
}

#define start_thread(regs, new_eip, new_esp) do { \
- __asm__("movl %0,%%fs ; movl %0,%%gs": :"r" (0)); \
+ __asm__("movl %0,%%fs": :"r" (0)); \
+ regs->xgs = 0; \
set_fs(USER_DS); \
regs->xds = __USER_DS; \
regs->xes = __USER_DS; \
diff -r 1b8b053ad03f include/asm-i386/ptrace.h
--- a/include/asm-i386/ptrace.h Mon Sep 25 23:31:01 2006 -0700
+++ b/include/asm-i386/ptrace.h Mon Sep 25 23:31:04 2006 -0700
@@ -33,6 +33,8 @@ struct pt_regs {
long eax;
int xds;
int xes;
+ /* int xfs; */
+ int xgs;
long orig_eax;
long eip;
int xcs;
diff -r 1b8b053ad03f kernel/fork.c
--- a/kernel/fork.c Mon Sep 25 23:31:01 2006 -0700
+++ b/kernel/fork.c Mon Sep 25 23:31:04 2006 -0700
@@ -1299,7 +1299,7 @@ fork_out:
return ERR_PTR(retval);
}

-struct pt_regs * __devinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
+noinline struct pt_regs * __devinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
{
memset(regs, 0, sizeof(struct pt_regs));
return regs;
Fix places where using %gs changes the usermode ABI.

There are a few places where the change in struct pt_regs and the use
of %gs affect the userspace ABI. These are primarily debugging
interfaces where thread state can be inspected or extracted.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>
Cc: Chuck Ebbert <76306.1226@xxxxxxxxxxxxxx>
Cc: Zachary Amsden <zach@xxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxx>

---
arch/i386/kernel/process.c | 6 +++---
arch/i386/kernel/ptrace.c | 18 ++++++------------
include/asm-i386/elf.h | 2 +-
include/asm-i386/unwind.h | 1 +
4 files changed, 11 insertions(+), 16 deletions(-)

===================================================================
--- a/arch/i386/kernel/process.c
+++ b/arch/i386/kernel/process.c
@@ -309,8 +309,8 @@ void show_regs(struct pt_regs * regs)
regs->eax,regs->ebx,regs->ecx,regs->edx);
printk("ESI: %08lx EDI: %08lx EBP: %08lx",
regs->esi, regs->edi, regs->ebp);
- printk(" DS: %04x ES: %04x\n",
- 0xffff & regs->xds,0xffff & regs->xes);
+ printk(" DS: %04x ES: %04x GS: %04x\n",
+ 0xffff & regs->xds,0xffff & regs->xes, 0xffff & regs->xgs);

cr0 = read_cr0();
cr2 = read_cr2();
@@ -504,7 +504,7 @@ void dump_thread(struct pt_regs * regs,
dump->regs.ds = regs->xds;
dump->regs.es = regs->xes;
savesegment(fs,dump->regs.fs);
- savesegment(gs,dump->regs.gs);
+ dump->regs.gs = regs->xgs;
dump->regs.orig_eax = regs->orig_eax;
dump->regs.eip = regs->eip;
dump->regs.cs = regs->xcs;
===================================================================
--- a/arch/i386/kernel/ptrace.c
+++ b/arch/i386/kernel/ptrace.c
@@ -94,13 +94,9 @@ static int putreg(struct task_struct *ch
return -EIO;
child->thread.fs = value;
return 0;
- case GS:
- if (value && (value & 3) != 3)
- return -EIO;
- child->thread.gs = value;
- return 0;
case DS:
case ES:
+ case GS:
if (value && (value & 3) != 3)
return -EIO;
value &= 0xffff;
@@ -116,8 +112,8 @@ static int putreg(struct task_struct *ch
value |= get_stack_long(child, EFL_OFFSET) & ~FLAG_MASK;
break;
}
- if (regno > GS*4)
- regno -= 2*4;
+ if (regno > ES*4)
+ regno -= 1*4;
put_stack_long(child, regno - sizeof(struct pt_regs), value);
return 0;
}
@@ -131,18 +127,16 @@ static unsigned long getreg(struct task_
case FS:
retval = child->thread.fs;
break;
- case GS:
- retval = child->thread.gs;
- break;
case DS:
case ES:
+ case GS:
case SS:
case CS:
retval = 0xffff;
/* fall through */
default:
- if (regno > GS*4)
- regno -= 2*4;
+ if (regno > ES*4)
+ regno -= 1*4;
regno = regno - sizeof(struct pt_regs);
retval &= get_stack_long(child, regno);
}
===================================================================
--- a/include/asm-i386/elf.h
+++ b/include/asm-i386/elf.h
@@ -88,7 +88,7 @@ typedef struct user_fxsr_struct elf_fpxr
pr_reg[7] = regs->xds; \
pr_reg[8] = regs->xes; \
savesegment(fs,pr_reg[9]); \
- savesegment(gs,pr_reg[10]); \
+ pr_reg[10] = regs->xgs; \
pr_reg[11] = regs->orig_eax; \
pr_reg[12] = regs->eip; \
pr_reg[13] = regs->xcs; \
===================================================================
--- a/include/asm-i386/unwind.h
+++ b/include/asm-i386/unwind.h
@@ -64,6 +64,7 @@ static inline void arch_unw_init_blocked
info->regs.xss = __KERNEL_DS;
info->regs.xds = __USER_DS;
info->regs.xes = __USER_DS;
+ info->regs.xgs = __KERNEL_PDA;
}

extern asmlinkage int arch_unwind_init_running(struct unwind_frame_info *,
Update sys_vm86 to cope with changed pt_regs and %gs usage.

sys_vm86 uses a struct kernel_vm86_regs, which is identical to
pt_regs, but adds an extra space for all the segment registers.
Previously this structure was completely independent, so changes in
pt_regs had to be reflected in kernel_vm86_regs. This changes just
embeds pt_regs in kernel_vm86_regs, and makes the appropriate changes
to vm86.c to deal with the new naming.

Also, since %gs is dealt with differently in the kernel, this change
adjusts vm86.c to reflect this.

While making these changes, I also cleaned up some frankly bizarre
code which was added when auditing was added to sys_vm86.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>
Cc: Chuck Ebbert <76306.1226@xxxxxxxxxxxxxx>
Cc: Zachary Amsden <zach@xxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Jason Baron <jbaron@xxxxxxxxxx>
Cc: Chris Wright <chrisw@xxxxxxxxxxxx>

---
arch/i386/kernel/vm86.c | 125 ++++++++++++++++++++++++++++-------------------
include/asm-i386/vm86.h | 17 ------
2 files changed, 78 insertions(+), 64 deletions(-)

diff -r 448ac068c03f arch/i386/kernel/vm86.c
--- a/arch/i386/kernel/vm86.c Sun Sep 24 19:26:47 2006 -0700
+++ b/arch/i386/kernel/vm86.c Sun Sep 24 19:26:50 2006 -0700
@@ -43,6 +43,7 @@
#include <linux/highmem.h>
#include <linux/ptrace.h>
#include <linux/audit.h>
+#include <linux/stddef.h>

#include <asm/uaccess.h>
#include <asm/io.h>
@@ -72,10 +73,10 @@
/*
* 8- and 16-bit register defines..
*/
-#define AL(regs) (((unsigned char *)&((regs)->eax))[0])
-#define AH(regs) (((unsigned char *)&((regs)->eax))[1])
-#define IP(regs) (*(unsigned short *)&((regs)->eip))
-#define SP(regs) (*(unsigned short *)&((regs)->esp))
+#define AL(regs) (((unsigned char *)&((regs)->pt.eax))[0])
+#define AH(regs) (((unsigned char *)&((regs)->pt.eax))[1])
+#define IP(regs) (*(unsigned short *)&((regs)->pt.eip))
+#define SP(regs) (*(unsigned short *)&((regs)->pt.esp))

/*
* virtual flags (16 and 32-bit versions)
@@ -89,10 +90,37 @@
#define SAFE_MASK (0xDD5)
#define RETURN_MASK (0xDFF)

-#define VM86_REGS_PART2 orig_eax
-#define VM86_REGS_SIZE1 \
- ( (unsigned)( & (((struct kernel_vm86_regs *)0)->VM86_REGS_PART2) ) )
-#define VM86_REGS_SIZE2 (sizeof(struct kernel_vm86_regs) - VM86_REGS_SIZE1)
+/* convert kernel_vm86_regs to vm86_regs */
+static int copy_vm86_regs_to_user(struct vm86_regs __user *user,
+ const struct kernel_vm86_regs *regs)
+{
+ int ret = 0;
+
+ /* kernel_vm86_regs is missing xfs, so copy everything up to
+ (but not including) xgs, and then rest after xgs. */
+ ret += copy_to_user(user, regs, offsetof(struct kernel_vm86_regs, pt.xgs));
+ ret += copy_to_user(&user->__null_gs, &regs->pt.xgs,
+ sizeof(struct kernel_vm86_regs) -
+ offsetof(struct kernel_vm86_regs, pt.xgs));
+
+ return ret;
+}
+
+/* convert vm86_regs to kernel_vm86_regs */
+static int copy_vm86_regs_from_user(struct kernel_vm86_regs *regs,
+ const struct vm86_regs __user *user,
+ unsigned extra)
+{
+ int ret = 0;
+
+ ret += copy_from_user(regs, user, offsetof(struct kernel_vm86_regs, pt.xgs));
+ ret += copy_from_user(&regs->pt.xgs, &user->__null_gs,
+ sizeof(struct kernel_vm86_regs) -
+ offsetof(struct kernel_vm86_regs, pt.xgs) +
+ extra);
+
+ return ret;
+}

struct pt_regs * FASTCALL(save_v86_state(struct kernel_vm86_regs * regs));
struct pt_regs * fastcall save_v86_state(struct kernel_vm86_regs * regs)
@@ -112,10 +140,8 @@ struct pt_regs * fastcall save_v86_state
printk("no vm86_info: BAD\n");
do_exit(SIGSEGV);
}
- set_flags(regs->eflags, VEFLAGS, VIF_MASK | current->thread.v86mask);
- tmp = copy_to_user(&current->thread.vm86_info->regs,regs, VM86_REGS_SIZE1);
- tmp += copy_to_user(&current->thread.vm86_info->regs.VM86_REGS_PART2,
- &regs->VM86_REGS_PART2, VM86_REGS_SIZE2);
+ set_flags(regs->pt.eflags, VEFLAGS, VIF_MASK | current->thread.v86mask);
+ tmp = copy_vm86_regs_to_user(&current->thread.vm86_info->regs,regs);
tmp += put_user(current->thread.screen_bitmap,&current->thread.vm86_info->screen_bitmap);
if (tmp) {
printk("vm86: could not access userspace vm86_info\n");
@@ -129,9 +155,11 @@ struct pt_regs * fastcall save_v86_state
current->thread.saved_esp0 = 0;
put_cpu();

+ ret = KVM86->regs32;
+
loadsegment(fs, current->thread.saved_fs);
- loadsegment(gs, current->thread.saved_gs);
- ret = KVM86->regs32;
+ ret->xgs = current->thread.saved_gs;
+
return ret;
}

@@ -183,9 +211,9 @@ asmlinkage int sys_vm86old(struct pt_reg
tsk = current;
if (tsk->thread.saved_esp0)
goto out;
- tmp = copy_from_user(&info, v86, VM86_REGS_SIZE1);
- tmp += copy_from_user(&info.regs.VM86_REGS_PART2, &v86->regs.VM86_REGS_PART2,
- (long)&info.vm86plus - (long)&info.regs.VM86_REGS_PART2);
+ tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs,
+ offsetof(struct kernel_vm86_struct, vm86plus) -
+ sizeof(info.regs));
ret = -EFAULT;
if (tmp)
goto out;
@@ -233,9 +261,9 @@ asmlinkage int sys_vm86(struct pt_regs r
if (tsk->thread.saved_esp0)
goto out;
v86 = (struct vm86plus_struct __user *)regs.ecx;
- tmp = copy_from_user(&info, v86, VM86_REGS_SIZE1);
- tmp += copy_from_user(&info.regs.VM86_REGS_PART2, &v86->regs.VM86_REGS_PART2,
- (long)&info.regs32 - (long)&info.regs.VM86_REGS_PART2);
+ tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs,
+ offsetof(struct kernel_vm86_struct, regs32) -
+ sizeof(info.regs));
ret = -EFAULT;
if (tmp)
goto out;
@@ -252,15 +280,15 @@ static void do_sys_vm86(struct kernel_vm
static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk)
{
struct tss_struct *tss;
- long eax;
/*
* make sure the vm86() system call doesn't try to do anything silly
*/
- info->regs.__null_ds = 0;
- info->regs.__null_es = 0;
-
-/* we are clearing fs,gs later just before "jmp resume_userspace",
- * because starting with Linux 2.1.x they aren't no longer saved/restored
+ info->regs.pt.xds = 0;
+ info->regs.pt.xes = 0;
+ info->regs.pt.xgs = 0;
+
+/* we are clearing fs later just before "jmp resume_userspace",
+ * because it is not saved/restored.
*/

/*
@@ -268,10 +296,10 @@ static void do_sys_vm86(struct kernel_vm
* has set it up safely, so this makes sure interrupt etc flags are
* inherited from protected mode.
*/
- VEFLAGS = info->regs.eflags;
- info->regs.eflags &= SAFE_MASK;
- info->regs.eflags |= info->regs32->eflags & ~SAFE_MASK;
- info->regs.eflags |= VM_MASK;
+ VEFLAGS = info->regs.pt.eflags;
+ info->regs.pt.eflags &= SAFE_MASK;
+ info->regs.pt.eflags |= info->regs32->eflags & ~SAFE_MASK;
+ info->regs.pt.eflags |= VM_MASK;

switch (info->cpu_type) {
case CPU_286:
@@ -294,7 +322,7 @@ static void do_sys_vm86(struct kernel_vm
info->regs32->eax = 0;
tsk->thread.saved_esp0 = tsk->thread.esp0;
savesegment(fs, tsk->thread.saved_fs);
- savesegment(gs, tsk->thread.saved_gs);
+ tsk->thread.saved_gs = info->regs32->xgs;

tss = &per_cpu(init_tss, get_cpu());
tsk->thread.esp0 = (unsigned long) &info->VM86_TSS_ESP0;
@@ -306,19 +334,18 @@ static void do_sys_vm86(struct kernel_vm
tsk->thread.screen_bitmap = info->screen_bitmap;
if (info->flags & VM86_SCREEN_BITMAP)
mark_screen_rdonly(tsk->mm);
- __asm__ __volatile__("xorl %eax,%eax; movl %eax,%fs; movl %eax,%gs\n\t");
- __asm__ __volatile__("movl %%eax, %0\n" :"=r"(eax));

/*call audit_syscall_exit since we do not exit via the normal paths */
if (unlikely(current->audit_context))
- audit_syscall_exit(AUDITSC_RESULT(eax), eax);
+ audit_syscall_exit(AUDITSC_RESULT(0), 0);

__asm__ __volatile__(
"movl %0,%%esp\n\t"
"movl %1,%%ebp\n\t"
+ "mov %2, %%fs\n\t"
"jmp resume_userspace"
: /* no outputs */
- :"r" (&info->regs), "r" (task_thread_info(tsk)));
+ :"r" (&info->regs), "r" (task_thread_info(tsk)), "r" (0));
/* we never return here */
}

@@ -348,12 +375,12 @@ static inline void clear_IF(struct kerne

static inline void clear_TF(struct kernel_vm86_regs * regs)
{
- regs->eflags &= ~TF_MASK;
+ regs->pt.eflags &= ~TF_MASK;
}

static inline void clear_AC(struct kernel_vm86_regs * regs)
{
- regs->eflags &= ~AC_MASK;
+ regs->pt.eflags &= ~AC_MASK;
}

/* It is correct to call set_IF(regs) from the set_vflags_*
@@ -370,7 +397,7 @@ static inline void set_vflags_long(unsig
static inline void set_vflags_long(unsigned long eflags, struct kernel_vm86_regs * regs)
{
set_flags(VEFLAGS, eflags, current->thread.v86mask);
- set_flags(regs->eflags, eflags, SAFE_MASK);
+ set_flags(regs->pt.eflags, eflags, SAFE_MASK);
if (eflags & IF_MASK)
set_IF(regs);
else
@@ -380,7 +407,7 @@ static inline void set_vflags_short(unsi
static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_regs * regs)
{
set_flags(VFLAGS, flags, current->thread.v86mask);
- set_flags(regs->eflags, flags, SAFE_MASK);
+ set_flags(regs->pt.eflags, flags, SAFE_MASK);
if (flags & IF_MASK)
set_IF(regs);
else
@@ -389,7 +416,7 @@ static inline void set_vflags_short(unsi

static inline unsigned long get_vflags(struct kernel_vm86_regs * regs)
{
- unsigned long flags = regs->eflags & RETURN_MASK;
+ unsigned long flags = regs->pt.eflags & RETURN_MASK;

if (VEFLAGS & VIF_MASK)
flags |= IF_MASK;
@@ -493,7 +520,7 @@ static void do_int(struct kernel_vm86_re
unsigned long __user *intr_ptr;
unsigned long segoffs;

- if (regs->cs == BIOSSEG)
+ if (regs->pt.xcs == BIOSSEG)
goto cannot_handle;
if (is_revectored(i, &KVM86->int_revectored))
goto cannot_handle;
@@ -505,9 +532,9 @@ static void do_int(struct kernel_vm86_re
if ((segoffs >> 16) == BIOSSEG)
goto cannot_handle;
pushw(ssp, sp, get_vflags(regs), cannot_handle);
- pushw(ssp, sp, regs->cs, cannot_handle);
+ pushw(ssp, sp, regs->pt.xcs, cannot_handle);
pushw(ssp, sp, IP(regs), cannot_handle);
- regs->cs = segoffs >> 16;
+ regs->pt.xcs = segoffs >> 16;
SP(regs) -= 6;
IP(regs) = segoffs & 0xffff;
clear_TF(regs);
@@ -524,7 +551,7 @@ int handle_vm86_trap(struct kernel_vm86_
if (VMPI.is_vm86pus) {
if ( (trapno==3) || (trapno==1) )
return_to_32bit(regs, VM86_TRAP + (trapno << 8));
- do_int(regs, trapno, (unsigned char __user *) (regs->ss << 4), SP(regs));
+ do_int(regs, trapno, (unsigned char __user *) (regs->pt.xss << 4), SP(regs));
return 0;
}
if (trapno !=1)
@@ -560,10 +587,10 @@ void handle_vm86_fault(struct kernel_vm8
handle_vm86_trap(regs, 0, 1); \
return; } while (0)

- orig_flags = *(unsigned short *)&regs->eflags;
-
- csp = (unsigned char __user *) (regs->cs << 4);
- ssp = (unsigned char __user *) (regs->ss << 4);
+ orig_flags = *(unsigned short *)&regs->pt.eflags;
+
+ csp = (unsigned char __user *) (regs->pt.xcs << 4);
+ ssp = (unsigned char __user *) (regs->pt.xss << 4);
sp = SP(regs);
ip = IP(regs);

@@ -650,7 +677,7 @@ void handle_vm86_fault(struct kernel_vm8
SP(regs) += 6;
}
IP(regs) = newip;
- regs->cs = newcs;
+ regs->pt.xcs = newcs;
CHECK_IF_IN_TRAP;
if (data32) {
set_vflags_long(newflags, regs);
diff -r 448ac068c03f include/asm-i386/vm86.h
--- a/include/asm-i386/vm86.h Sun Sep 24 19:26:47 2006 -0700
+++ b/include/asm-i386/vm86.h Sun Sep 24 22:33:53 2006 -0700
@@ -145,26 +145,13 @@ struct vm86plus_struct {
* at the end of the structure. Look at ptrace.h to see the "normal"
* setup. For user space layout see 'struct vm86_regs' above.
*/
+#include <asm/ptrace.h>

struct kernel_vm86_regs {
/*
* normal regs, with special meaning for the segment descriptors..
*/
- long ebx;
- long ecx;
- long edx;
- long esi;
- long edi;
- long ebp;
- long eax;
- long __null_ds;
- long __null_es;
- long orig_eax;
- long eip;
- unsigned short cs, __csh;
- long eflags;
- long esp;
- unsigned short ss, __ssh;
+ struct pt_regs pt;
/*
* these are specific to v86 mode:
*/
Implement smp_processor_id() with the PDA.

Use the cpu_number in the PDA to implement raw_smp_processor_id. This
is a little simpler than using thread_info, though the cpu field in
thread_info cannot be removed since it is used for things other than
getting the current CPU in common code.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>
Cc: Chuck Ebbert <76306.1226@xxxxxxxxxxxxxx>
Cc: Zachary Amsden <zach@xxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxx>

---
arch/i386/kernel/asm-offsets.c | 2 +-
include/asm-i386/smp.h | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)

diff -r 412e9eb1cd8b arch/i386/kernel/asm-offsets.c
--- a/arch/i386/kernel/asm-offsets.c Mon Sep 25 15:23:51 2006 -0700
+++ b/arch/i386/kernel/asm-offsets.c Mon Sep 25 15:23:53 2006 -0700
@@ -52,7 +52,6 @@ void foo(void)
OFFSET(TI_exec_domain, thread_info, exec_domain);
OFFSET(TI_flags, thread_info, flags);
OFFSET(TI_status, thread_info, status);
- OFFSET(TI_cpu, thread_info, cpu);
OFFSET(TI_preempt_count, thread_info, preempt_count);
OFFSET(TI_addr_limit, thread_info, addr_limit);
OFFSET(TI_restart_block, thread_info, restart_block);
@@ -96,4 +95,5 @@ void foo(void)

BLANK();
OFFSET(PDA_pcurrent, i386_pda, pcurrent);
+ OFFSET(PDA_cpu, i386_pda, cpu_number);
}
diff -r 412e9eb1cd8b include/asm-i386/smp.h
--- a/include/asm-i386/smp.h Mon Sep 25 15:23:51 2006 -0700
+++ b/include/asm-i386/smp.h Mon Sep 25 15:23:53 2006 -0700
@@ -8,6 +8,7 @@
#include <linux/kernel.h>
#include <linux/threads.h>
#include <linux/cpumask.h>
+#include <asm/pda.h>
#endif

#ifdef CONFIG_X86_LOCAL_APIC
@@ -56,7 +57,7 @@ extern void cpu_uninit(void);
* from the initial startup. We map APIC_BASE very early in page_setup(),
* so this is correct in the x86 case.
*/
-#define raw_smp_processor_id() (current_thread_info()->cpu)
+#define raw_smp_processor_id() (read_pda(cpu_number))

extern cpumask_t cpu_callout_map;
extern cpumask_t cpu_callin_map;
Implement "current" with the PDA.

Use the pcurrent field in the PDA to implement the "current" macro.
This ends up compiling down to a single instruction to get the current
task.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>
Cc: Chuck Ebbert <76306.1226@xxxxxxxxxxxxxx>
Cc: Zachary Amsden <zach@xxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxx>

---
include/asm-i386/current.h | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff -r 5eb01c4f49fe include/asm-i386/current.h
--- a/include/asm-i386/current.h Mon Sep 25 23:05:11 2006 -0700
+++ b/include/asm-i386/current.h Mon Sep 25 23:05:12 2006 -0700
@@ -1,13 +1,14 @@
#ifndef _I386_CURRENT_H
#define _I386_CURRENT_H

-#include <linux/thread_info.h>
+#include <asm/pda.h>
+#include <linux/compiler.h>

struct task_struct;

-static __always_inline struct task_struct * get_current(void)
+static __always_inline struct task_struct *get_current(void)
{
- return current_thread_info()->task;
+ return read_pda(pcurrent);
}

#define current get_current()

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