diff options
| author | Sami Tolvanen <samitolvanen@google.com> | 2020-04-27 18:00:16 +0200 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2020-05-15 17:35:50 +0200 |
| commit | 5287569a790d2546a06db07e391bf84b8bd6cf51 (patch) | |
| tree | 137dc42c9e15afc1b7880798d2ea1ed146301211 /arch/arm64/kernel/entry.S | |
| parent | arm64: Disable SCS for hypervisor code (diff) | |
| download | linux-5287569a790d2546a06db07e391bf84b8bd6cf51.tar.xz linux-5287569a790d2546a06db07e391bf84b8bd6cf51.zip | |
arm64: Implement Shadow Call Stack
This change implements shadow stack switching, initial SCS set-up,
and interrupt shadow stacks for arm64.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/kernel/entry.S')
| -rw-r--r-- | arch/arm64/kernel/entry.S | 24 |
1 files changed, 22 insertions, 2 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index ddcde093c433..244268d5ae47 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -23,6 +23,7 @@ #include <asm/mmu.h> #include <asm/processor.h> #include <asm/ptrace.h> +#include <asm/scs.h> #include <asm/thread_info.h> #include <asm/asm-uaccess.h> #include <asm/unistd.h> @@ -179,6 +180,8 @@ alternative_cb_end apply_ssbd 1, x22, x23 ptrauth_keys_install_kernel tsk, 1, x20, x22, x23 + + scs_load tsk, x20 .else add x21, sp, #S_FRAME_SIZE get_current_task tsk @@ -343,6 +346,8 @@ alternative_else_nop_endif msr cntkctl_el1, x1 4: #endif + scs_save tsk, x0 + /* No kernel C function calls after this as user keys are set. */ ptrauth_keys_install_user tsk, x0, x1, x2 @@ -388,6 +393,9 @@ alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0 .macro irq_stack_entry mov x19, sp // preserve the original sp +#ifdef CONFIG_SHADOW_CALL_STACK + mov x24, x18 // preserve the original shadow stack +#endif /* * Compare sp with the base of the task stack. @@ -405,15 +413,25 @@ alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0 /* switch to the irq stack */ mov sp, x26 + +#ifdef CONFIG_SHADOW_CALL_STACK + /* also switch to the irq shadow stack */ + adr_this_cpu x18, irq_shadow_call_stack, x26 +#endif + 9998: .endm /* - * x19 should be preserved between irq_stack_entry and - * irq_stack_exit. + * The callee-saved regs (x19-x29) should be preserved between + * irq_stack_entry and irq_stack_exit, but note that kernel_entry + * uses x20-x23 to store data for later use. */ .macro irq_stack_exit mov sp, x19 +#ifdef CONFIG_SHADOW_CALL_STACK + mov x18, x24 +#endif .endm /* GPRs used by entry code */ @@ -901,6 +919,8 @@ SYM_FUNC_START(cpu_switch_to) mov sp, x9 msr sp_el0, x1 ptrauth_keys_install_kernel x1, 1, x8, x9, x10 + scs_save x0, x8 + scs_load x1, x8 ret SYM_FUNC_END(cpu_switch_to) NOKPROBE(cpu_switch_to) |