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linux/arch/arm64/include/asm/scs.h

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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>
2020-04-27 16:00:16 +00:00
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_SCS_H
#define _ASM_SCS_H
#ifdef __ASSEMBLY__
arm64: scs: Store absolute SCS stack pointer value in thread_info Storing the SCS information in thread_info as a {base,offset} pair introduces an additional load instruction on the ret-to-user path, since the SCS stack pointer in x18 has to be converted back to an offset by subtracting the base. Replace the offset with the absolute SCS stack pointer value instead and avoid the redundant load. Tested-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
2020-05-15 13:11:05 +00:00
#include <asm/asm-offsets.h>
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>
2020-04-27 16:00:16 +00:00
#ifdef CONFIG_SHADOW_CALL_STACK
arm64: scs: Use 'scs_sp' register alias for x18 x18 holds the SCS stack pointer value, so introduce a register alias to make this easier to read in assembly code. Tested-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
2020-05-15 13:46:46 +00:00
scs_sp .req x18
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>
2020-04-27 16:00:16 +00:00
.macro scs_load tsk, tmp
arm64: scs: Use 'scs_sp' register alias for x18 x18 holds the SCS stack pointer value, so introduce a register alias to make this easier to read in assembly code. Tested-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
2020-05-15 13:46:46 +00:00
ldr scs_sp, [\tsk, #TSK_TI_SCS_SP]
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>
2020-04-27 16:00:16 +00:00
.endm
.macro scs_save tsk, tmp
arm64: scs: Use 'scs_sp' register alias for x18 x18 holds the SCS stack pointer value, so introduce a register alias to make this easier to read in assembly code. Tested-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
2020-05-15 13:46:46 +00:00
str scs_sp, [\tsk, #TSK_TI_SCS_SP]
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>
2020-04-27 16:00:16 +00:00
.endm
#else
.macro scs_load tsk, tmp
.endm
.macro scs_save tsk, tmp
.endm
#endif /* CONFIG_SHADOW_CALL_STACK */
#endif /* __ASSEMBLY __ */
#endif /* _ASM_SCS_H */
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