[PATCH 1/2] x86-64: Directly access per-cpu IST

From: Brian Gerst
Date: Sat Jul 31 2010 - 12:48:38 EST


Use a direct per-cpu reference for the IST instead of using a scratch
register.

Signed-off-by: Brian Gerst <brgerst@xxxxxxxxx>
---
arch/x86/kernel/entry_64.S | 6 +++---
1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 4db7c4d..59af275 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -1065,6 +1065,7 @@ ENTRY(\sym)
END(\sym)
.endm

+#define INIT_TSS_IST(x) PER_CPU_VAR(init_tss) + (TSS_ist + ((x) - 1) * 8)
.macro paranoidzeroentry_ist sym do_sym ist
ENTRY(\sym)
INTR_FRAME
@@ -1076,10 +1077,9 @@ ENTRY(\sym)
TRACE_IRQS_OFF
movq %rsp,%rdi /* pt_regs pointer */
xorl %esi,%esi /* no error code */
- PER_CPU(init_tss, %r12)
- subq $EXCEPTION_STKSZ, TSS_ist + (\ist - 1) * 8(%r12)
+ subq $EXCEPTION_STKSZ, INIT_TSS_IST(\ist)
call \do_sym
- addq $EXCEPTION_STKSZ, TSS_ist + (\ist - 1) * 8(%r12)
+ addq $EXCEPTION_STKSZ, INIT_TSS_IST(\ist)
jmp paranoid_exit /* %ebx: no swapgs flag */
CFI_ENDPROC
END(\sym)
--
1.7.2

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