Messages in this thread | | | Subject | Re: [PATCH v4 13/17] arm64: preserve x18 when CPU is suspended | Date | Mon, 04 Nov 2019 14:29:59 +0109 | From | Marc Zyngier <> |
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On 2019-11-01 23:21, Sami Tolvanen wrote: > Don't lose the current task's shadow stack when the CPU is suspended. > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com> > Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > Reviewed-by: Kees Cook <keescook@chromium.org> > --- > arch/arm64/include/asm/suspend.h | 2 +- > arch/arm64/mm/proc.S | 10 ++++++++++ > 2 files changed, 11 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/include/asm/suspend.h > b/arch/arm64/include/asm/suspend.h > index 8939c87c4dce..0cde2f473971 100644 > --- a/arch/arm64/include/asm/suspend.h > +++ b/arch/arm64/include/asm/suspend.h > @@ -2,7 +2,7 @@ > #ifndef __ASM_SUSPEND_H > #define __ASM_SUSPEND_H > > -#define NR_CTX_REGS 12 > +#define NR_CTX_REGS 13 > #define NR_CALLEE_SAVED_REGS 12 > > /* > diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S > index fdabf40a83c8..5616dc52a033 100644 > --- a/arch/arm64/mm/proc.S > +++ b/arch/arm64/mm/proc.S > @@ -49,6 +49,8 @@ > * cpu_do_suspend - save CPU registers context > * > * x0: virtual address of context pointer > + * > + * This must be kept in sync with struct cpu_suspend_ctx in > <asm/suspend.h>. > */ > ENTRY(cpu_do_suspend) > mrs x2, tpidr_el0 > @@ -73,6 +75,9 @@ alternative_endif > stp x8, x9, [x0, #48] > stp x10, x11, [x0, #64] > stp x12, x13, [x0, #80] > +#ifdef CONFIG_SHADOW_CALL_STACK > + str x18, [x0, #96] > +#endif
Do we need the #ifdefery here? We didn't add that to the KVM path, and I'd feel better having a single behaviour, specially when NR_CTX_REGS is unconditionally sized to hold 13 regs.
> ret > ENDPROC(cpu_do_suspend) > > @@ -89,6 +94,11 @@ ENTRY(cpu_do_resume) > ldp x9, x10, [x0, #48] > ldp x11, x12, [x0, #64] > ldp x13, x14, [x0, #80] > +#ifdef CONFIG_SHADOW_CALL_STACK > + ldr x18, [x0, #96] > + /* Clear the SCS pointer from the state buffer */ > + str xzr, [x0, #96] > +#endif > msr tpidr_el0, x2 > msr tpidrro_el0, x3 > msr contextidr_el1, x4
Thanks,
M. -- Jazz is not dead. It just smells funny...
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