[PATCH 04/23] x86, realmode: Move reboot_32.S to unified realmode code
From: Jarkko Sakkinen
Date: Tue May 08 2012 - 14:28:17 EST
Migrated reboot_32.S from x86_trampoline to the real-mode
blob.
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxx>
---
arch/x86/include/asm/realmode.h | 4 ++
arch/x86/kernel/Makefile | 1 -
arch/x86/kernel/reboot.c | 25 +------
arch/x86/kernel/reboot_32.S | 135 --------------------------------------
arch/x86/realmode/rm/Makefile | 1 +
arch/x86/realmode/rm/header.S | 3 +
arch/x86/realmode/rm/reboot_32.S | 134 +++++++++++++++++++++++++++++++++++++
7 files changed, 145 insertions(+), 158 deletions(-)
delete mode 100644 arch/x86/kernel/reboot_32.S
create mode 100644 arch/x86/realmode/rm/reboot_32.S
diff --git a/arch/x86/include/asm/realmode.h b/arch/x86/include/asm/realmode.h
index dc1bba5..bf26b06 100644
--- a/arch/x86/include/asm/realmode.h
+++ b/arch/x86/include/asm/realmode.h
@@ -9,6 +9,10 @@ struct real_mode_header {
u32 text_start;
u32 ro_end;
u32 end;
+ /* reboot */
+#ifdef CONFIG_X86_32
+ u32 machine_real_restart_asm;
+#endif
} __attribute__((__packed__));
extern struct real_mode_header real_mode_header;
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index f9e19d4..b71ef35 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -49,7 +49,6 @@ obj-$(CONFIG_STACKTRACE) += stacktrace.o
obj-y += cpu/
obj-y += acpi/
obj-y += reboot.o
-obj-$(CONFIG_X86_32) += reboot_32.o
obj-$(CONFIG_MCA) += mca_32.o
obj-$(CONFIG_X86_MSR) += msr.o
obj-$(CONFIG_X86_CPUID) += cpuid.o
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index d840e69..050eff2 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -24,6 +24,7 @@
#ifdef CONFIG_X86_32
# include <linux/ctype.h>
# include <linux/mc146818rtc.h>
+# include <asm/realmode.h>
#else
# include <asm/x86_init.h>
#endif
@@ -332,15 +333,10 @@ static int __init reboot_init(void)
}
core_initcall(reboot_init);
-extern const unsigned char machine_real_restart_asm[];
-extern const u64 machine_real_restart_gdt[3];
-
void machine_real_restart(unsigned int type)
{
- void *restart_va;
- unsigned long restart_pa;
- void (*restart_lowmem)(unsigned int);
- u64 *lowmem_gdt;
+ void (*restart_lowmem)(unsigned int) = (void (*)(unsigned int))
+ real_mode_header.machine_real_restart_asm;
local_irq_disable();
@@ -369,21 +365,6 @@ void machine_real_restart(unsigned int type)
too. */
*((unsigned short *)0x472) = reboot_mode;
- /* Patch the GDT in the low memory trampoline */
- lowmem_gdt = TRAMPOLINE_SYM(machine_real_restart_gdt);
-
- restart_va = TRAMPOLINE_SYM(machine_real_restart_asm);
- restart_pa = virt_to_phys(restart_va);
- restart_lowmem = (void (*)(unsigned int))restart_pa;
-
- /* GDT[0]: GDT self-pointer */
- lowmem_gdt[0] =
- (u64)(sizeof(machine_real_restart_gdt) - 1) +
- ((u64)virt_to_phys(lowmem_gdt) << 16);
- /* GDT[1]: 64K real mode code segment */
- lowmem_gdt[1] =
- GDT_ENTRY(0x009b, restart_pa, 0xffff);
-
/* Jump to the identity-mapped low memory code */
restart_lowmem(type);
}
diff --git a/arch/x86/kernel/reboot_32.S b/arch/x86/kernel/reboot_32.S
deleted file mode 100644
index 1d5c46d..0000000
--- a/arch/x86/kernel/reboot_32.S
+++ /dev/null
@@ -1,135 +0,0 @@
-#include <linux/linkage.h>
-#include <linux/init.h>
-#include <asm/segment.h>
-#include <asm/page_types.h>
-
-/*
- * The following code and data reboots the machine by switching to real
- * mode and jumping to the BIOS reset entry point, as if the CPU has
- * really been reset. The previous version asked the keyboard
- * controller to pulse the CPU reset line, which is more thorough, but
- * doesn't work with at least one type of 486 motherboard. It is easy
- * to stop this code working; hence the copious comments.
- *
- * This code is called with the restart type (0 = BIOS, 1 = APM) in %eax.
- */
- .section ".x86_trampoline","a"
- .balign 16
- .code32
-ENTRY(machine_real_restart_asm)
-r_base = .
- /* Get our own relocated address */
- call 1f
-1: popl %ebx
- subl $(1b - r_base), %ebx
-
- /* Compute the equivalent real-mode segment */
- movl %ebx, %ecx
- shrl $4, %ecx
-
- /* Patch post-real-mode segment jump */
- movw (dispatch_table - r_base)(%ebx,%eax,2),%ax
- movw %ax, (101f - r_base)(%ebx)
- movw %cx, (102f - r_base)(%ebx)
-
- /* Set up the IDT for real mode. */
- lidtl (machine_real_restart_idt - r_base)(%ebx)
-
- /*
- * Set up a GDT from which we can load segment descriptors for real
- * mode. The GDT is not used in real mode; it is just needed here to
- * prepare the descriptors.
- */
- lgdtl (machine_real_restart_gdt - r_base)(%ebx)
-
- /*
- * Load the data segment registers with 16-bit compatible values
- */
- movl $16, %ecx
- movl %ecx, %ds
- movl %ecx, %es
- movl %ecx, %fs
- movl %ecx, %gs
- movl %ecx, %ss
- ljmpl $8, $1f - r_base
-
-/*
- * This is 16-bit protected mode code to disable paging and the cache,
- * switch to real mode and jump to the BIOS reset code.
- *
- * The instruction that switches to real mode by writing to CR0 must be
- * followed immediately by a far jump instruction, which set CS to a
- * valid value for real mode, and flushes the prefetch queue to avoid
- * running instructions that have already been decoded in protected
- * mode.
- *
- * Clears all the flags except ET, especially PG (paging), PE
- * (protected-mode enable) and TS (task switch for coprocessor state
- * save). Flushes the TLB after paging has been disabled. Sets CD and
- * NW, to disable the cache on a 486, and invalidates the cache. This
- * is more like the state of a 486 after reset. I don't know if
- * something else should be done for other chips.
- *
- * More could be done here to set up the registers as if a CPU reset had
- * occurred; hopefully real BIOSs don't assume much. This is not the
- * actual BIOS entry point, anyway (that is at 0xfffffff0).
- *
- * Most of this work is probably excessive, but it is what is tested.
- */
- .code16
-1:
- xorl %ecx, %ecx
- movl %cr0, %eax
- andl $0x00000011, %eax
- orl $0x60000000, %eax
- movl %eax, %cr0
- movl %ecx, %cr3
- movl %cr0, %edx
- andl $0x60000000, %edx /* If no cache bits -> no wbinvd */
- jz 2f
- wbinvd
-2:
- andb $0x10, %al
- movl %eax, %cr0
- .byte 0xea /* ljmpw */
-101: .word 0 /* Offset */
-102: .word 0 /* Segment */
-
-bios:
- ljmpw $0xf000, $0xfff0
-
-apm:
- movw $0x1000, %ax
- movw %ax, %ss
- movw $0xf000, %sp
- movw $0x5307, %ax
- movw $0x0001, %bx
- movw $0x0003, %cx
- int $0x15
-
-END(machine_real_restart_asm)
-
- .balign 16
- /* These must match <asm/reboot.h */
-dispatch_table:
- .word bios - r_base
- .word apm - r_base
-END(dispatch_table)
-
- .balign 16
-machine_real_restart_idt:
- .word 0xffff /* Length - real mode default value */
- .long 0 /* Base - real mode default value */
-END(machine_real_restart_idt)
-
- .balign 16
-ENTRY(machine_real_restart_gdt)
- .quad 0 /* Self-pointer, filled in by PM code */
- .quad 0 /* 16-bit code segment, filled in by PM code */
- /*
- * 16-bit data segment with the selector value 16 = 0x10 and
- * base value 0x100; since this is consistent with real mode
- * semantics we don't have to reload the segments once CR0.PE = 0.
- */
- .quad GDT_ENTRY(0x0093, 0x100, 0xffff)
-END(machine_real_restart_gdt)
diff --git a/arch/x86/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile
index 7c3f202..3f851c4 100644
--- a/arch/x86/realmode/rm/Makefile
+++ b/arch/x86/realmode/rm/Makefile
@@ -12,6 +12,7 @@ subdir- := wakeup
always := realmode.bin
realmode-y += header.o
+realmode-$(CONFIG_X86_32) += reboot_32.o
targets += $(realmode-y)
diff --git a/arch/x86/realmode/rm/header.S b/arch/x86/realmode/rm/header.S
index 7be17f2..db21401 100644
--- a/arch/x86/realmode/rm/header.S
+++ b/arch/x86/realmode/rm/header.S
@@ -13,4 +13,7 @@ ENTRY(real_mode_header)
.long pa_text_start
.long pa_ro_end
.long pa_end
+#ifdef CONFIG_X86_32
+ .long pa_machine_real_restart_asm
+#endif
END(real_mode_header)
diff --git a/arch/x86/realmode/rm/reboot_32.S b/arch/x86/realmode/rm/reboot_32.S
new file mode 100644
index 0000000..83803c2
--- /dev/null
+++ b/arch/x86/realmode/rm/reboot_32.S
@@ -0,0 +1,134 @@
+#include <linux/linkage.h>
+#include <linux/init.h>
+#include <asm/segment.h>
+#include <asm/page_types.h>
+
+/*
+ * The following code and data reboots the machine by switching to real
+ * mode and jumping to the BIOS reset entry point, as if the CPU has
+ * really been reset. The previous version asked the keyboard
+ * controller to pulse the CPU reset line, which is more thorough, but
+ * doesn't work with at least one type of 486 motherboard. It is easy
+ * to stop this code working; hence the copious comments.
+ *
+ * This code is called with the restart type (0 = BIOS, 1 = APM) in %eax.
+ */
+ .section ".text32", "ax"
+ .code32
+ .globl machine_real_restart_asm
+
+ .balign 16
+machine_real_restart_asm:
+ /* Set up the IDT for real mode. */
+ lidtl pa_machine_real_restart_idt
+
+ /*
+ * Set up a GDT from which we can load segment descriptors for real
+ * mode. The GDT is not used in real mode; it is just needed here to
+ * prepare the descriptors.
+ */
+ lgdtl pa_machine_real_restart_gdt
+
+ /*
+ * Load the data segment registers with 16-bit compatible values
+ */
+ movl $16, %ecx
+ movl %ecx, %ds
+ movl %ecx, %es
+ movl %ecx, %fs
+ movl %ecx, %gs
+ movl %ecx, %ss
+ ljmpw $8, $1f
+
+/*
+ * This is 16-bit protected mode code to disable paging and the cache,
+ * switch to real mode and jump to the BIOS reset code.
+ *
+ * The instruction that switches to real mode by writing to CR0 must be
+ * followed immediately by a far jump instruction, which set CS to a
+ * valid value for real mode, and flushes the prefetch queue to avoid
+ * running instructions that have already been decoded in protected
+ * mode.
+ *
+ * Clears all the flags except ET, especially PG (paging), PE
+ * (protected-mode enable) and TS (task switch for coprocessor state
+ * save). Flushes the TLB after paging has been disabled. Sets CD and
+ * NW, to disable the cache on a 486, and invalidates the cache. This
+ * is more like the state of a 486 after reset. I don't know if
+ * something else should be done for other chips.
+ *
+ * More could be done here to set up the registers as if a CPU reset had
+ * occurred; hopefully real BIOSs don't assume much. This is not the
+ * actual BIOS entry point, anyway (that is at 0xfffffff0).
+ *
+ * Most of this work is probably excessive, but it is what is tested.
+ */
+ .text
+ .code16
+
+ .balign 16
+machine_real_restart_asm16:
+1:
+ xorl %ecx, %ecx
+ movl %cr0, %edx
+ andl $0x00000011, %edx
+ orl $0x60000000, %edx
+ movl %edx, %cr0
+ movl %ecx, %cr3
+ movl %cr0, %edx
+ andl $0x60000000, %edx /* If no cache bits -> no wbinvd */
+ jz 2f
+ wbinvd
+2:
+ andb $0x10, %dl
+ movl %edx, %cr0
+ .byte 0xea /* ljmpw */
+ .word 3f /* Offset */
+ .word real_mode_seg /* Segment */
+
+3:
+ testb $0, %al
+ jz bios
+
+apm:
+ movw $0x1000, %ax
+ movw %ax, %ss
+ movw $0xf000, %sp
+ movw $0x5307, %ax
+ movw $0x0001, %bx
+ movw $0x0003, %cx
+ int $0x15
+ /* This should never return... */
+
+bios:
+ ljmpw $0xf000, $0xfff0
+
+ .section ".rodata", "a"
+ .globl machine_real_restart_idt, machine_real_restart_gdt
+
+ .balign 16
+machine_real_restart_idt:
+ .word 0xffff /* Length - real mode default value */
+ .long 0 /* Base - real mode default value */
+
+ .balign 16
+machine_real_restart_gdt:
+ /* Self-pointer */
+ .word 0xffff /* Length - real mode default value */
+ .long pa_machine_real_restart_gdt
+ .word 0
+
+ /*
+ * 16-bit code segment pointing to real_mode_seg
+ * Selector value 8
+ */
+ .word 0xffff /* Limit */
+ .long 0x9b000000 + pa_real_mode_base
+ .word 0
+
+ /*
+ * 16-bit data segment with the selector value 16 = 0x10 and
+ * base value 0x100; since this is consistent with real mode
+ * semantics we don't have to reload the segments once CR0.PE = 0.
+ */
+ .quad GDT_ENTRY(0x0093, 0x100, 0xffff)
--
1.7.9.5
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