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SubjectRe: [patch 37/60] x86mm//kpti: Force entry through trampoline when KPTI active
On Mon, Dec 04, 2017 at 03:07:43PM +0100, Thomas Gleixner wrote:
> From: Thomas Gleixner <tglx@linutronix.de>
>
> Force the entry through the trampoline only when KPTI is active. Otherwise
> go through the normal entry code.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
>
> ---
> arch/x86/kernel/cpu/common.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> --- a/arch/x86/kernel/cpu/common.c
> +++ b/arch/x86/kernel/cpu/common.c
> @@ -1458,7 +1458,10 @@ void syscall_init(void)
> (entry_SYSCALL_64_trampoline - _entry_trampoline);
>
> wrmsr(MSR_STAR, 0, (__USER32_CS << 16) | __KERNEL_CS);
> - wrmsrl(MSR_LSTAR, SYSCALL64_entry_trampoline);
> + if (static_cpu_has_bug(X86_BUG_CPU_SECURE_MODE_KPTI))
> + wrmsrl(MSR_LSTAR, SYSCALL64_entry_trampoline);
> + else
> + wrmsrl(MSR_LSTAR, (unsigned long)entry_SYSCALL_64);
>
> #ifdef CONFIG_IA32_EMULATION
> wrmsrl(MSR_CSTAR, (unsigned long)entry_SYSCALL_compat);

Just a nitpick:

Subject: x86/mm/kpti:...

Otherwise,

Reviewed-by: Borislav Petkov <bp@suse.de>

--
Regards/Gruss,
Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--

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