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x86/asm/entry/64/compat: Change the 32-bit sysenter code to use sp0

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The ia32 sysenter code loaded the top of the kernel stack into
rsp by loading kernel_stack and then adjusting it.  It can be
simplified to just read sp0 directly.

This requires the addition of a new asm-offsets entry for sp0.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/88ff9006163d296a0665338585c36d9bfb85235d.1425611534.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2015-03-05 19:19:04 -08:00 committed by Ingo Molnar
parent 75182b1632
commit 9d0c914c60
2 changed files with 2 additions and 2 deletions
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3
arch/x86/ia32/ia32entry.S
View File

@ -113,8 +113,7 @@ ENTRY(ia32_sysenter_target)
CFI_DEF_CFA rsp,0
CFI_REGISTER rsp,rbp
SWAPGS_UNSAFE_STACK
movq PER_CPU_VAR(kernel_stack), %rsp
addq $(KERNEL_STACK_OFFSET),%rsp
movq PER_CPU_VAR(init_tss + TSS_sp0), %rsp
/*
* No need to follow this irqs on/off section: the syscall
* disabled irqs, here we enable it straight after entry:

1
arch/x86/kernel/asm-offsets_64.c
View File

@ -81,6 +81,7 @@ int main(void)
#undef ENTRY
OFFSET(TSS_ist, tss_struct, x86_tss.ist);
OFFSET(TSS_sp0, tss_struct, x86_tss.sp0);
BLANK();
DEFINE(__NR_syscall_max, sizeof(syscalls_64) - 1);