| Message ID | 20191018161033.261971-14-samitolvanen@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | add support for Clang's Shadow Call Stack | expand |
On Fri, Oct 18, 2019 at 9:11 AM Sami Tolvanen <samitolvanen@google.com> wrote: > > Don't lose the current task's shadow stack when the CPU is suspended. > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com> > --- > arch/arm64/mm/proc.S | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S > index fdabf40a83c8..9a8bd4bc8549 100644 > --- a/arch/arm64/mm/proc.S > +++ b/arch/arm64/mm/proc.S > @@ -73,6 +73,9 @@ alternative_endif > stp x8, x9, [x0, #48] > stp x10, x11, [x0, #64] > stp x12, x13, [x0, #80] > +#ifdef CONFIG_SHADOW_CALL_STACK > + stp x18, xzr, [x0, #96] Could this be a str/ldr of just x18 rather than stp/ldp of x18 + garbage? Maybe there's no real cost difference, or some kind of alignment invariant? > +#endif > ret > ENDPROC(cpu_do_suspend) > > @@ -89,6 +92,9 @@ ENTRY(cpu_do_resume) > ldp x9, x10, [x0, #48] > ldp x11, x12, [x0, #64] > ldp x13, x14, [x0, #80] > +#ifdef CONFIG_SHADOW_CALL_STACK > + ldp x18, x19, [x0, #96] > +#endif > msr tpidr_el0, x2 > msr tpidrro_el0, x3 > msr contextidr_el1, x4 > -- > 2.23.0.866.gb869b98d4c-goog >
On Fri, Oct 18, 2019 at 9:49 AM Nick Desaulniers <ndesaulniers@google.com> wrote: > > diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S > > index fdabf40a83c8..9a8bd4bc8549 100644 > > --- a/arch/arm64/mm/proc.S > > +++ b/arch/arm64/mm/proc.S > > @@ -73,6 +73,9 @@ alternative_endif > > stp x8, x9, [x0, #48] > > stp x10, x11, [x0, #64] > > stp x12, x13, [x0, #80] > > +#ifdef CONFIG_SHADOW_CALL_STACK > > + stp x18, xzr, [x0, #96] > > Could this be a str/ldr of just x18 rather than stp/ldp of x18 + > garbage? Maybe there's no real cost difference, or some kind of > alignment invariant? Sure, this can be changed to str/ldr. I don't think there's a noticeable difference in cost. Sami
On Fri, Oct 18, 2019 at 09:10:28AM -0700, 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> > --- > arch/arm64/mm/proc.S | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S > index fdabf40a83c8..9a8bd4bc8549 100644 > --- a/arch/arm64/mm/proc.S > +++ b/arch/arm64/mm/proc.S > @@ -73,6 +73,9 @@ alternative_endif > stp x8, x9, [x0, #48] > stp x10, x11, [x0, #64] > stp x12, x13, [x0, #80] > +#ifdef CONFIG_SHADOW_CALL_STACK > + stp x18, xzr, [x0, #96] > +#endif This should have a corresponding change to cpu_suspend_ctx in <asm/suspend.h>. Otherwise we're corrupting a portion of the stack. Mark. > ret > ENDPROC(cpu_do_suspend) > > @@ -89,6 +92,9 @@ ENTRY(cpu_do_resume) > ldp x9, x10, [x0, #48] > ldp x11, x12, [x0, #64] > ldp x13, x14, [x0, #80] > +#ifdef CONFIG_SHADOW_CALL_STACK > + ldp x18, x19, [x0, #96] > +#endif > msr tpidr_el0, x2 > msr tpidrro_el0, x3 > msr contextidr_el1, x4 > -- > 2.23.0.866.gb869b98d4c-goog >
On Mon, Oct 21, 2019 at 9:56 AM Mark Rutland <mark.rutland@arm.com> wrote: > This should have a corresponding change to cpu_suspend_ctx in > <asm/suspend.h>. Otherwise we're corrupting a portion of the stack. Ugh, correct. I'll fix this in the next version. Thanks. Sami
On Mon, Oct 21, 2019 at 03:43:14PM -0700, Sami Tolvanen wrote: > On Mon, Oct 21, 2019 at 9:56 AM Mark Rutland <mark.rutland@arm.com> wrote: > > This should have a corresponding change to cpu_suspend_ctx in > > <asm/suspend.h>. Otherwise we're corrupting a portion of the stack. > > Ugh, correct. I'll fix this in the next version. Thanks. It's probably worth extending the comment above cpu_do_suspend to say: | This must be kept in sync with struct cpu_suspend_ctx in | <asm/suspend.h> ... to match what we have above struct cpu_suspend_ctx, and make this more obvious in future. Thanks, Mark.
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index fdabf40a83c8..9a8bd4bc8549 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -73,6 +73,9 @@ alternative_endif stp x8, x9, [x0, #48] stp x10, x11, [x0, #64] stp x12, x13, [x0, #80] +#ifdef CONFIG_SHADOW_CALL_STACK + stp x18, xzr, [x0, #96] +#endif ret ENDPROC(cpu_do_suspend) @@ -89,6 +92,9 @@ ENTRY(cpu_do_resume) ldp x9, x10, [x0, #48] ldp x11, x12, [x0, #64] ldp x13, x14, [x0, #80] +#ifdef CONFIG_SHADOW_CALL_STACK + ldp x18, x19, [x0, #96] +#endif msr tpidr_el0, x2 msr tpidrro_el0, x3 msr contextidr_el1, x4
Don't lose the current task's shadow stack when the CPU is suspended. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> --- arch/arm64/mm/proc.S | 6 ++++++ 1 file changed, 6 insertions(+)