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authorJeremy Fitzhardinge <jeremy@goop.org>2007-02-13 13:26:20 +0100
committerAndi Kleen <andi@basil.nowhere.org>2007-02-13 13:26:20 +0100
commit464d1a78fbf8cf6c7fd970e7b3e2db50a320ce28 (patch)
tree536d8a92976e675b484b35dec88d40c97fab8ac8 /arch/i386/kernel/entry.S
parent54413927f022292aeccadd268fbf1c0b42129945 (diff)
[PATCH] i386: Convert i386 PDA code to use %fs
Convert the PDA code to use %fs rather than %gs as the segment for per-processor data. This is because some processors show a small but measurable performance gain for reloading a NULL segment selector (as %fs generally is in user-space) versus a non-NULL one (as %gs generally is). On modern processors the difference is very small, perhaps undetectable. Some old AMD "K6 3D+" processors are noticably slower when %fs is used rather than %gs; I have no idea why this might be, but I think they're sufficiently rare that it doesn't matter much. This patch also fixes the math emulator, which had not been adjusted to match the changed struct pt_regs. [frederik.deweerdt@gmail.com: fixit with gdb] [mingo@elte.hu: Fix KVM too] Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: Andi Kleen <ak@suse.de> Cc: Ian Campbell <Ian.Campbell@XenSource.com> Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Zachary Amsden <zach@vmware.com> Cc: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: Frederik Deweerdt <frederik.deweerdt@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org>
Diffstat (limited to 'arch/i386/kernel/entry.S')
-rw-r--r--arch/i386/kernel/entry.S32
1 files changed, 16 insertions, 16 deletions
diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S
index 5e47683fc63..8c6a22a42d2 100644
--- a/arch/i386/kernel/entry.S
+++ b/arch/i386/kernel/entry.S
@@ -30,7 +30,7 @@
* 18(%esp) - %eax
* 1C(%esp) - %ds
* 20(%esp) - %es
- * 24(%esp) - %gs
+ * 24(%esp) - %fs
* 28(%esp) - orig_eax
* 2C(%esp) - %eip
* 30(%esp) - %cs
@@ -99,9 +99,9 @@ VM_MASK = 0x00020000
#define SAVE_ALL \
cld; \
- pushl %gs; \
+ pushl %fs; \
CFI_ADJUST_CFA_OFFSET 4;\
- /*CFI_REL_OFFSET gs, 0;*/\
+ /*CFI_REL_OFFSET fs, 0;*/\
pushl %es; \
CFI_ADJUST_CFA_OFFSET 4;\
/*CFI_REL_OFFSET es, 0;*/\
@@ -133,7 +133,7 @@ VM_MASK = 0x00020000
movl %edx, %ds; \
movl %edx, %es; \
movl $(__KERNEL_PDA), %edx; \
- movl %edx, %gs
+ movl %edx, %fs
#define RESTORE_INT_REGS \
popl %ebx; \
@@ -166,9 +166,9 @@ VM_MASK = 0x00020000
2: popl %es; \
CFI_ADJUST_CFA_OFFSET -4;\
/*CFI_RESTORE es;*/\
-3: popl %gs; \
+3: popl %fs; \
CFI_ADJUST_CFA_OFFSET -4;\
- /*CFI_RESTORE gs;*/\
+ /*CFI_RESTORE fs;*/\
.pushsection .fixup,"ax"; \
4: movl $0,(%esp); \
jmp 1b; \
@@ -349,11 +349,11 @@ sysenter_past_esp:
movl PT_OLDESP(%esp), %ecx
xorl %ebp,%ebp
TRACE_IRQS_ON
-1: mov PT_GS(%esp), %gs
+1: mov PT_FS(%esp), %fs
ENABLE_INTERRUPTS_SYSEXIT
CFI_ENDPROC
.pushsection .fixup,"ax"
-2: movl $0,PT_GS(%esp)
+2: movl $0,PT_FS(%esp)
jmp 1b
.section __ex_table,"a"
.align 4
@@ -550,7 +550,7 @@ syscall_badsys:
#define FIXUP_ESPFIX_STACK \
/* since we are on a wrong stack, we cant make it a C code :( */ \
- movl %gs:PDA_cpu, %ebx; \
+ movl %fs:PDA_cpu, %ebx; \
PER_CPU(cpu_gdt_descr, %ebx); \
movl GDS_address(%ebx), %ebx; \
GET_DESC_BASE(GDT_ENTRY_ESPFIX_SS, %ebx, %eax, %ax, %al, %ah); \
@@ -632,7 +632,7 @@ KPROBE_ENTRY(page_fault)
CFI_ADJUST_CFA_OFFSET 4
ALIGN
error_code:
- /* the function address is in %gs's slot on the stack */
+ /* the function address is in %fs's slot on the stack */
pushl %es
CFI_ADJUST_CFA_OFFSET 4
/*CFI_REL_OFFSET es, 0*/
@@ -661,20 +661,20 @@ error_code:
CFI_ADJUST_CFA_OFFSET 4
CFI_REL_OFFSET ebx, 0
cld
- pushl %gs
+ pushl %fs
CFI_ADJUST_CFA_OFFSET 4
- /*CFI_REL_OFFSET gs, 0*/
+ /*CFI_REL_OFFSET fs, 0*/
movl $(__KERNEL_PDA), %ecx
- movl %ecx, %gs
+ movl %ecx, %fs
UNWIND_ESPFIX_STACK
popl %ecx
CFI_ADJUST_CFA_OFFSET -4
/*CFI_REGISTER es, ecx*/
- movl PT_GS(%esp), %edi # get the function address
+ movl PT_FS(%esp), %edi # get the function address
movl PT_ORIG_EAX(%esp), %edx # get the error code
movl $-1, PT_ORIG_EAX(%esp) # no syscall to restart
- mov %ecx, PT_GS(%esp)
- /*CFI_REL_OFFSET gs, ES*/
+ mov %ecx, PT_FS(%esp)
+ /*CFI_REL_OFFSET fs, ES*/
movl $(__USER_DS), %ecx
movl %ecx, %ds
movl %ecx, %es