From 464d1a78fbf8cf6c7fd970e7b3e2db50a320ce28 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Tue, 13 Feb 2007 13:26:20 +0100 Subject: [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 Signed-off-by: Andi Kleen Cc: Ian Campbell Acked-by: Ingo Molnar Acked-by: Zachary Amsden Cc: Eric Dumazet Signed-off-by: Frederik Deweerdt Signed-off-by: Andrew Morton --- include/asm-i386/ptrace.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/asm-i386/ptrace.h') diff --git a/include/asm-i386/ptrace.h b/include/asm-i386/ptrace.h index bdbc894339b..1646996c73d 100644 --- a/include/asm-i386/ptrace.h +++ b/include/asm-i386/ptrace.h @@ -16,8 +16,8 @@ struct pt_regs { long eax; int xds; int xes; - /* int xfs; */ - int xgs; + int xfs; + /* int xgs; */ long orig_eax; long eip; int xcs; -- cgit v1.2.3 From 7b3552024380f306a6c50d5105d18d9d4258fa4e Mon Sep 17 00:00:00 2001 From: Zachary Amsden Date: Tue, 13 Feb 2007 13:26:21 +0100 Subject: [PATCH] i386: Profile pc badness Profile_pc was broken when using paravirtualization because the assumption the kernel was running at CPL 0 was violated, causing bad logic to read a random value off the stack. The only way to be in kernel lock functions is to be in kernel code, so validate that assumption explicitly by checking the CS value. We don't want to be fooled by BIOS / APM segments and try to read those stacks, so only match KERNEL_CS. I moved some stuff in segment.h to make it prettier. Signed-off-by: Zachary Amsden Signed-off-by: Andi Kleen --- include/asm-i386/ptrace.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include/asm-i386/ptrace.h') diff --git a/include/asm-i386/ptrace.h b/include/asm-i386/ptrace.h index 1646996c73d..6002597b9e1 100644 --- a/include/asm-i386/ptrace.h +++ b/include/asm-i386/ptrace.h @@ -49,6 +49,10 @@ static inline int user_mode_vm(struct pt_regs *regs) { return ((regs->xcs & SEGMENT_RPL_MASK) | (regs->eflags & VM_MASK)) >= USER_RPL; } +static inline int v8086_mode(struct pt_regs *regs) +{ + return (regs->eflags & VM_MASK); +} #define instruction_pointer(regs) ((regs)->eip) #define regs_return_value(regs) ((regs)->eax) -- cgit v1.2.3