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x86/asm/entry/64: Always set up SYSENTER MSRs 

On CONFIG_IA32_EMULATION=y kernels we set up
MSR_IA32_SYSENTER_CS/ESP/EIP, but on !CONFIG_IA32_EMULATION
kernels we leave them unchanged.

Clear them to make sure the instruction is disabled properly.

SYSCALL is set up properly in both cases.

Acked-by: Denys Vlasenko <dvlasenk@redhat.com>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Will Drewry <wad@chromium.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
hifive-unleashed-5.1
Ingo Molnar 2015-03-24 14:41:37 +01:00
parent 84f5378845
commit d56fe4bf5f
1 changed files with 7 additions and 3 deletions
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10
arch/x86/kernel/cpu/common.c
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@ -1169,9 +1169,8 @@ void syscall_init(void)
*/
wrmsrl(MSR_STAR, ((u64)__USER32_CS)<<48 | ((u64)__KERNEL_CS)<<32);
wrmsrl(MSR_LSTAR, system_call);
#ifndef CONFIG_IA32_EMULATION
wrmsrl(MSR_CSTAR, ignore_sysret);
#else
#ifdef CONFIG_IA32_EMULATION
wrmsrl(MSR_CSTAR, ia32_cstar_target);
/*
* Always load these, in case some future 64-bit CPU supports
@ -1180,6 +1179,11 @@ void syscall_init(void)
wrmsrl_safe(MSR_IA32_SYSENTER_CS, (u64)__KERNEL_CS);
wrmsrl_safe(MSR_IA32_SYSENTER_ESP, 0ULL);
wrmsrl_safe(MSR_IA32_SYSENTER_EIP, (u64)ia32_sysenter_target);
#else
wrmsrl(MSR_CSTAR, ignore_sysret);
wrmsrl_safe(MSR_IA32_SYSENTER_CS, 0);
wrmsrl_safe(MSR_IA32_SYSENTER_ESP, 0ULL);
wrmsrl_safe(MSR_IA32_SYSENTER_EIP, 0ULL);
#endif
/* Flags to clear on syscall */