diff options
| author | Sami Tolvanen <samitolvanen@google.com> | 2020-04-27 09:00:12 -0700 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2020-05-15 16:35:50 +0100 |
| commit | 6d37d81f449a103a8b43c5c972b5055b8936ef0e (patch) | |
| tree | 86b92094d4b520b008f4545bf7f1e97bddaa1d68 | |
| parent | da64e9d1f8c3dad6898dac6edb39a68d3aa9ce93 (diff) | |
| download | linux-6d37d81f449a103a8b43c5c972b5055b8936ef0e.tar.gz linux-6d37d81f449a103a8b43c5c972b5055b8936ef0e.tar.bz2 linux-6d37d81f449a103a8b43c5c972b5055b8936ef0e.zip | |
arm64: Preserve register x18 when CPU is suspended
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>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
| -rw-r--r-- | arch/arm64/include/asm/suspend.h | 2 | ||||
| -rw-r--r-- | arch/arm64/mm/proc.S | 14 |
2 files changed, 15 insertions, 1 deletions
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 197a9ba2d5ea..ed15be0f8103 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -58,6 +58,8 @@ * 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>. */ SYM_FUNC_START(cpu_do_suspend) mrs x2, tpidr_el0 @@ -82,6 +84,11 @@ alternative_endif stp x8, x9, [x0, #48] stp x10, x11, [x0, #64] stp x12, x13, [x0, #80] + /* + * Save x18 as it may be used as a platform register, e.g. by shadow + * call stack. + */ + str x18, [x0, #96] ret SYM_FUNC_END(cpu_do_suspend) @@ -98,6 +105,13 @@ SYM_FUNC_START(cpu_do_resume) ldp x9, x10, [x0, #48] ldp x11, x12, [x0, #64] ldp x13, x14, [x0, #80] + /* + * Restore x18, as it may be used as a platform register, and clear + * the buffer to minimize the risk of exposure when used for shadow + * call stack. + */ + ldr x18, [x0, #96] + str xzr, [x0, #96] msr tpidr_el0, x2 msr tpidrro_el0, x3 msr contextidr_el1, x4 |