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x86/asm/entry/64: Fold syscall32_cpu_init() into its sole user

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Having syscall32/sysenter32 initialization in a separate tiny
function, called from within a function that is already syscall
init specific, serves no real purpose.

Its existense also caused an unintended effect of having
wrmsrl(MSR_CSTAR) performed twice: once we set it to a dummy
function returning -ENOSYS, and immediately after
(if CONFIG_IA32_EMULATION), we set it to point to the proper
syscall32 entry point, ia32_cstar_target.

Signed-off-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>
This commit is contained in:
Denys Vlasenko 2015-03-22 20:48:14 +01:00 committed by Ingo Molnar
parent 34061f134f
commit a76c7f4604
1 changed files with 10 additions and 21 deletions
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31
arch/x86/kernel/cpu/common.c
View file

@ -959,24 +959,6 @@ static void identify_cpu(struct cpuinfo_x86 *c)
#endif
}
#ifdef CONFIG_X86_64
# ifdef CONFIG_IA32_EMULATION
/* May not be __init: called during resume */
static void syscall32_cpu_init(void)
{
/*
* Always load these, in case some future 64-bit CPU supports
* SYSENTER from compat mode too:
*/
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);
wrmsrl(MSR_CSTAR, ia32_cstar_target);
}
# endif
#endif
/*
* Set up the CPU state needed to execute SYSENTER/SYSEXIT instructions
* on 32-bit kernels:
@ -1187,10 +1169,17 @@ 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);
#ifdef CONFIG_IA32_EMULATION
syscall32_cpu_init();
#else
wrmsrl(MSR_CSTAR, ia32_cstar_target);
/*
* Always load these, in case some future 64-bit CPU supports
* SYSENTER from compat mode too:
*/
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);
#endif
/* Flags to clear on syscall */