[tip:x86/trampoline] x86, realmode: Move SMP trampoline to unified realmode code

From: tip-bot for Jarkko Sakkinen
Date: Tue May 08 2012 - 18:17:36 EST

Commit-ID: 48927bbb97c7d4cf343c05827ab9ac30c60678cb
Gitweb: http://git.kernel.org/tip/48927bbb97c7d4cf343c05827ab9ac30c60678cb
Author: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxx>
AuthorDate: Tue, 8 May 2012 21:22:28 +0300
Committer: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
CommitDate: Tue, 8 May 2012 11:41:51 -0700

x86, realmode: Move SMP trampoline to unified realmode code

Migrated SMP trampoline code to the real mode blob.
SMP trampoline code is not yet removed from
.x86_trampoline because it is needed by the wakeup
code.

[ hpa: always enable compiling startup_32_smp in head_32.S... it is
only a few instructions which go into .init on UP builds, and it makes
the rest of the code less #ifdef ugly. ]

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1336501366-28617-6-git-send-email-jarkko.sakkinen@xxxxxxxxx
Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
---
arch/x86/include/asm/realmode.h | 18 ++++
arch/x86/kernel/head_32.S | 5 +-
arch/x86/kernel/head_64.S | 4 -
arch/x86/kernel/realmode.c | 14 +++
arch/x86/kernel/smpboot.c | 18 +++--
arch/x86/realmode/rm/Makefile | 1 +
arch/x86/realmode/rm/header.S | 11 +++
arch/x86/{kernel => realmode/rm}/trampoline_32.S | 63 ++++++++-------
arch/x86/{kernel => realmode/rm}/trampoline_64.S | 94 +++++++++++----------
9 files changed, 137 insertions(+), 91 deletions(-)

diff --git a/arch/x86/include/asm/realmode.h b/arch/x86/include/asm/realmode.h
index bf26b06..9b4a5da 100644
--- a/arch/x86/include/asm/realmode.h
+++ b/arch/x86/include/asm/realmode.h
@@ -13,6 +13,17 @@ struct real_mode_header {
#ifdef CONFIG_X86_32
u32 machine_real_restart_asm;
#endif
+ /* SMP trampoline */
+ u32 trampoline_data;
+ u32 trampoline_status;
+#ifdef CONFIG_X86_32
+ u32 startup_32_smp;
+ u32 boot_gdt;
+#else
+ u32 startup_64_smp;
+ u32 level3_ident_pgt;
+ u32 level3_kernel_pgt;
+#endif
} __attribute__((__packed__));

extern struct real_mode_header real_mode_header;
@@ -25,6 +36,13 @@ extern unsigned long initial_gs;
extern unsigned char real_mode_blob[];
extern unsigned char real_mode_relocs[];

+#ifdef CONFIG_X86_32
+extern unsigned char startup_32_smp[];
+extern unsigned char boot_gdt[];
+#else
+extern unsigned char secondary_startup_64[];
+#endif
+
extern void __init setup_real_mode(void);

#endif /* _ARCH_X86_REALMODE_H */
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index ce0be7c..a3c2b4f 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -273,10 +273,7 @@ num_subarch_entries = (. - subarch_entries) / 4
* If cpu hotplug is not supported then this code can go in init section
* which will be freed later
*/
-
__CPUINIT
-
-#ifdef CONFIG_SMP
ENTRY(startup_32_smp)
cld
movl $(__BOOT_DS),%eax
@@ -287,7 +284,7 @@ ENTRY(startup_32_smp)
movl pa(stack_start),%ecx
movl %eax,%ss
leal -__PAGE_OFFSET(%ecx),%esp
-#endif /* CONFIG_SMP */
+
default_entry:

/*
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 40f4eb3..d70bc2e 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -136,10 +136,6 @@ ident_complete:
/* Fixup phys_base */
addq %rbp, phys_base(%rip)

- /* Fixup trampoline */
- addq %rbp, trampoline_level4_pgt + 0(%rip)
- addq %rbp, trampoline_level4_pgt + (511*8)(%rip)
-
/* Due to ENTRY(), sometimes the empty space gets filled with
* zeros. Better take a jmp than relying on empty space being
* filled with 0x90 (nop)
diff --git a/arch/x86/kernel/realmode.c b/arch/x86/kernel/realmode.c
index 7415c42..a465775 100644
--- a/arch/x86/kernel/realmode.c
+++ b/arch/x86/kernel/realmode.c
@@ -58,6 +58,20 @@ void __init setup_real_mode(void)
/* Copied header will contain relocated physical addresses. */
memcpy(&real_mode_header, real_mode_base,
sizeof(struct real_mode_header));
+
+#ifdef CONFIG_X86_32
+ *((u32 *)__va(real_mode_header.startup_32_smp)) = __pa(startup_32_smp);
+ *((u32 *)__va(real_mode_header.boot_gdt)) = __pa(boot_gdt);
+#else
+ *((u64 *) __va(real_mode_header.startup_64_smp)) =
+ (u64) __pa(secondary_startup_64);
+
+ *((u64 *) __va(real_mode_header.level3_ident_pgt)) =
+ __pa(level3_ident_pgt) + _KERNPG_TABLE;
+
+ *((u64 *) __va(real_mode_header.level3_kernel_pgt)) =
+ __pa(level3_kernel_pgt) + _KERNPG_TABLE;
+#endif
}

/*
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 6e1e406..c7971ea 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -57,7 +57,7 @@
#include <asm/nmi.h>
#include <asm/irq.h>
#include <asm/idle.h>
-#include <asm/trampoline.h>
+#include <asm/realmode.h>
#include <asm/cpu.h>
#include <asm/numa.h>
#include <asm/pgtable.h>
@@ -73,6 +73,8 @@
#include <asm/smpboot_hooks.h>
#include <asm/i8259.h>

+#include <asm/realmode.h>
+
/* State of each CPU */
DEFINE_PER_CPU(int, cpu_state) = { 0 };

@@ -662,8 +664,12 @@ static void __cpuinit announce_cpu(int cpu, int apicid)
*/
static int __cpuinit do_boot_cpu(int apicid, int cpu)
{
+ volatile u32 *trampoline_status =
+ (volatile u32 *) __va(real_mode_header.trampoline_status);
+ /* start_ip had better be page-aligned! */
+ unsigned long start_ip = real_mode_header.trampoline_data;
+
unsigned long boot_error = 0;
- unsigned long start_ip;
int timeout;
struct create_idle c_idle = {
.cpu = cpu,
@@ -713,9 +719,6 @@ do_rest:
initial_code = (unsigned long)start_secondary;
stack_start = c_idle.idle->thread.sp;

- /* start_ip had better be page-aligned! */
- start_ip = trampoline_address();
-
/* So we see what's up */
announce_cpu(cpu, apicid);

@@ -778,8 +781,7 @@ do_rest:
pr_debug("CPU%d: has booted.\n", cpu);
} else {
boot_error = 1;
- if (*(volatile u32 *)TRAMPOLINE_SYM(trampoline_status)
- == 0xA5A5A5A5)
+ if (*trampoline_status == 0xA5A5A5A5)
/* trampoline started but...? */
pr_err("CPU%d: Stuck ??\n", cpu);
else
@@ -805,7 +807,7 @@ do_rest:
}

/* mark "stuck" area as not stuck */
- *(volatile u32 *)TRAMPOLINE_SYM(trampoline_status) = 0;
+ *trampoline_status = 0;

if (get_uv_system_type() != UV_NON_UNIQUE_APIC) {
/*
diff --git a/arch/x86/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile
index 3f851c4..56ec64f 100644
--- a/arch/x86/realmode/rm/Makefile
+++ b/arch/x86/realmode/rm/Makefile
@@ -13,6 +13,7 @@ always := realmode.bin

realmode-y += header.o
realmode-$(CONFIG_X86_32) += reboot_32.o
+realmode-y += trampoline_$(BITS).o

targets += $(realmode-y)

diff --git a/arch/x86/realmode/rm/header.S b/arch/x86/realmode/rm/header.S
index db21401..a979004 100644
--- a/arch/x86/realmode/rm/header.S
+++ b/arch/x86/realmode/rm/header.S
@@ -16,4 +16,15 @@ ENTRY(real_mode_header)
#ifdef CONFIG_X86_32
.long pa_machine_real_restart_asm
#endif
+ /* SMP trampoline */
+ .long pa_trampoline_data
+ .long pa_trampoline_status
+#ifdef CONFIG_X86_32
+ .long pa_startup_32_smp
+ .long pa_boot_gdt
+#else
+ .long pa_startup_64_smp
+ .long pa_level3_ident_pgt
+ .long pa_level3_kernel_pgt
+#endif
END(real_mode_header)
diff --git a/arch/x86/kernel/trampoline_32.S b/arch/x86/realmode/rm/trampoline_32.S
similarity index 53%
copy from arch/x86/kernel/trampoline_32.S
copy to arch/x86/realmode/rm/trampoline_32.S
index 451c0a7..18cb7fc 100644
--- a/arch/x86/kernel/trampoline_32.S
+++ b/arch/x86/realmode/rm/trampoline_32.S
@@ -6,8 +6,8 @@
*
* This is only used for booting secondary CPUs in SMP machine
*
- * Entry: CS:IP point to the start of our code, we are
- * in real mode with no stack, but the rest of the
+ * Entry: CS:IP point to the start of our code, we are
+ * in real mode with no stack, but the rest of the
* trampoline page to make our stack and everything else
* is a mystery.
*
@@ -15,16 +15,14 @@
*
* On entry to trampoline_data, the processor is in real mode
* with 16-bit addressing and 16-bit data. CS has some value
- * and IP is zero. Thus, data addresses need to be absolute
- * (no relocation) and are taken with regard to r_base.
+ * and IP is zero. Thus, we load CS to the physical segment
+ * of the real mode code before doing anything further.
*
- * If you work on this file, check the object module with
- * objdump --reloc to make sure there are no relocation
- * entries except for:
+ * The structure real_mode_header includes entries that need
+ * to be set up before executing this code:
*
- * TYPE VALUE
- * R_386_32 startup_32_smp
- * R_386_32 boot_gdt
+ * startup_32_smp
+ * boot_gdt
*/

#include <linux/linkage.h>
@@ -32,21 +30,24 @@
#include <asm/segment.h>
#include <asm/page_types.h>

-#ifdef CONFIG_SMP
-
- .section ".x86_trampoline","a"
- .balign PAGE_SIZE
+ .text
.code16
+ .globl trampoline_data

-ENTRY(trampoline_data)
-r_base = .
+ .balign PAGE_SIZE
+trampoline_data:
wbinvd # Needed for NUMA-Q should be harmless for others
+
+ .byte 0xea # ljmpw
+ .word 1f # Offset
+ .word real_mode_seg # Segment
+1:
mov %cs, %ax # Code and data in the same place
mov %ax, %ds

cli # We should be safe anyway

- movl $0xA5A5A5A5, trampoline_status - r_base
+ movl $0xA5A5A5A5, trampoline_status
# write marker for master knows we're running

/* GDT tables in non default location kernel can be beyond 16MB and
@@ -55,29 +56,31 @@ r_base = .
* to 32 bit.
*/

- lidtl boot_idt_descr - r_base # load idt with 0, 0
- lgdtl boot_gdt_descr - r_base # load gdt with whatever is appropriate
+ lidtl boot_idt_descr # load idt with 0, 0
+ lgdtl boot_gdt_descr # load gdt with whatever is appropriate

xor %ax, %ax
- inc %ax # protected mode (PE) bit
- lmsw %ax # into protected mode
+ inc %ax # protected mode (PE) bit
+ lmsw %ax # into protected mode
+
# flush prefetch and jump to startup_32_smp in arch/i386/kernel/head.S
- ljmpl $__BOOT_CS, $(startup_32_smp-__PAGE_OFFSET)
+ ljmpl *(startup_32_smp)
+
+ .data
+ .globl startup_32_smp, boot_gdt, trampoline_status

- # These need to be in the same 64K segment as the above;
- # hence we don't use the boot_gdt_descr defined in head.S
boot_gdt_descr:
.word __BOOT_DS + 7 # gdt limit
- .long boot_gdt - __PAGE_OFFSET # gdt base
+boot_gdt:
+ .long 0 # gdt base

boot_idt_descr:
.word 0 # idt limit = 0
.long 0 # idt base = 0L

-ENTRY(trampoline_status)
+trampoline_status:
.long 0

-.globl trampoline_end
-trampoline_end:
-
-#endif /* CONFIG_SMP */
+startup_32_smp:
+ .long 0x00000000
+ .word __BOOT_CS, 0
diff --git a/arch/x86/kernel/trampoline_64.S b/arch/x86/realmode/rm/trampoline_64.S
similarity index 71%
copy from arch/x86/kernel/trampoline_64.S
copy to arch/x86/realmode/rm/trampoline_64.S
index 09ff517..063da00 100644
--- a/arch/x86/kernel/trampoline_64.S
+++ b/arch/x86/realmode/rm/trampoline_64.S
@@ -5,8 +5,8 @@
* 4 Jan 1997 Michael Chastain: changed to gnu as.
* 15 Sept 2005 Eric Biederman: 64bit PIC support
*
- * Entry: CS:IP point to the start of our code, we are
- * in real mode with no stack, but the rest of the
+ * Entry: CS:IP point to the start of our code, we are
+ * in real mode with no stack, but the rest of the
* trampoline page to make our stack and everything else
* is a mystery.
*
@@ -32,42 +32,33 @@
#include <asm/segment.h>
#include <asm/processor-flags.h>

- .section ".x86_trampoline","a"
+ .text
.balign PAGE_SIZE
.code16

ENTRY(trampoline_data)
-r_base = .
cli # We should be safe anyway
wbinvd
+
+ .byte 0xea # ljmpw
+ .word 1f # Offset
+ .word real_mode_seg # Segment
+1:
mov %cs, %ax # Code and data in the same place
mov %ax, %ds
mov %ax, %es
mov %ax, %ss

+ movl $0xA5A5A5A5, trampoline_status
+ # write marker for master knows we're running

- movl $0xA5A5A5A5, trampoline_status - r_base
- # write marker for master knows we're running
-
- # Setup stack
- movw $(trampoline_stack_end - r_base), %sp
+ # Setup stack
+ movw $trampoline_stack_end, %sp

call verify_cpu # Verify the cpu supports long mode
testl %eax, %eax # Check for return code
jnz no_longmode

- mov %cs, %ax
- movzx %ax, %esi # Find the 32bit trampoline location
- shll $4, %esi
-
- # Fixup the absolute vectors
- leal (startup_32 - r_base)(%esi), %eax
- movl %eax, startup_32_vector - r_base
- leal (startup_64 - r_base)(%esi), %eax
- movl %eax, startup_64_vector - r_base
- leal (tgdt - r_base)(%esi), %eax
- movl %eax, (tgdt + 2 - r_base)
-
/*
* GDT tables in non default location kernel can be beyond 16MB and
* lgdt will not be able to load the address as in real mode default
@@ -75,26 +66,34 @@ r_base = .
* to 32 bit.
*/

- lidtl tidt - r_base # load idt with 0, 0
- lgdtl tgdt - r_base # load gdt with whatever is appropriate
+ lidtl tidt # load idt with 0, 0
+ lgdtl tgdt # load gdt with whatever is appropriate

mov $X86_CR0_PE, %ax # protected mode (PE) bit
lmsw %ax # into protected mode

# flush prefetch and jump to startup_32
- ljmpl *(startup_32_vector - r_base)
+ ljmpl *(startup_32_vector)
+
+no_longmode:
+ hlt
+ jmp no_longmode
+#include "../kernel/verify_cpu.S"

.code32
.balign 4
-startup_32:
+ENTRY(startup_32)
movl $__KERNEL_DS, %eax # Initialize the %ds segment register
movl %eax, %ds

movl $X86_CR4_PAE, %eax
movl %eax, %cr4 # Enable PAE mode

+ movl pa_startup_64_smp, %esi
+ movl pa_startup_64_smp_high, %edi
+
# Setup trampoline 4 level pagetables
- leal (trampoline_level4_pgt - r_base)(%esi), %eax
+ leal pa_trampoline_level4_pgt, %eax
movl %eax, %cr3

movl $MSR_EFER, %ecx
@@ -113,22 +112,17 @@ startup_32:
* EFER.LMA = 1). Now we want to jump in 64bit mode, to do that we use
* the new gdt/idt that has __KERNEL_CS with CS.L = 1.
*/
- ljmp *(startup_64_vector - r_base)(%esi)
+ ljmpl *(pa_startup_64_vector)

.code64
.balign 4
-startup_64:
+ENTRY(startup_64)
# Now jump into the kernel using virtual addresses
- movq $secondary_startup_64, %rax
+ movl %edi, %eax
+ shlq $32, %rax
+ addl %esi, %eax
jmp *%rax

- .code16
-no_longmode:
- hlt
- jmp no_longmode
-#include "verify_cpu.S"
-
- .balign 4
# Careful these need to be in the same 64K segment as the above;
tidt:
.word 0 # idt limit = 0
@@ -137,10 +131,11 @@ tidt:
# Duplicate the global descriptor table
# so the kernel can live anywhere
.balign 4
+ .globl tgdt
tgdt:
.short tgdt_end - tgdt # gdt limit
- .long tgdt - r_base
- .short 0
+ .long pa_tgdt
+ .short 0
.quad 0x00cf9b000000ffff # __KERNEL32_CS
.quad 0x00af9b000000ffff # __KERNEL_CS
.quad 0x00cf93000000ffff # __KERNEL_DS
@@ -148,14 +143,17 @@ tgdt_end:

.balign 4
startup_32_vector:
- .long startup_32 - r_base
+ .long pa_startup_32
.word __KERNEL32_CS, 0

.balign 4
+ .globl startup_64_vector
startup_64_vector:
- .long startup_64 - r_base
+ .long pa_startup_64
.word __KERNEL_CS, 0

+ .data
+
.balign 4
ENTRY(trampoline_status)
.long 0
@@ -163,9 +161,15 @@ ENTRY(trampoline_status)
trampoline_stack:
.org 0x1000
trampoline_stack_end:
-ENTRY(trampoline_level4_pgt)
- .quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
- .fill 510,8,0
- .quad level3_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE

-ENTRY(trampoline_end)
+ .globl level3_ident_pgt
+ .globl level3_kernel_pgt
+ENTRY(trampoline_level4_pgt)
+ level3_ident_pgt: .quad 0
+ .fill 510,8,0
+ level3_kernel_pgt: .quad 0
+
+ .globl startup_64_smp
+ .globl startup_64_smp_high
+startup_64_smp: .long 0
+startup_64_smp_high: .long 0
--
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