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| author | Ard Biesheuvel <ardb@kernel.org> | 2022-10-27 17:59:08 +0200 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2022-11-09 19:06:35 +0100 |
| commit | 3b619e22c4601b444ed2d6a5458271f72625ac89 (patch) | |
| tree | 1f4754b78c6302a14322f629b72a6f195d8dd58e /arch/arm64/kernel/head.S | |
| parent | scs: add support for dynamic shadow call stacks (diff) | |
| download | linux-3b619e22c4601b444ed2d6a5458271f72625ac89.tar.xz linux-3b619e22c4601b444ed2d6a5458271f72625ac89.zip | |
arm64: implement dynamic shadow call stack for Clang
Implement dynamic shadow call stack support on Clang, by parsing the
unwind tables at init time to locate all occurrences of PACIASP/AUTIASP
instructions, and replacing them with the shadow call stack push and pop
instructions, respectively.
This is useful because the overhead of the shadow call stack is
difficult to justify on hardware that implements pointer authentication
(PAC), and given that the PAC instructions are executed as NOPs on
hardware that doesn't, we can just replace them without breaking
anything. As PACIASP/AUTIASP are guaranteed to be paired with respect to
manipulations of the return address, replacing them 1:1 with shadow call
stack pushes and pops is guaranteed to result in the desired behavior.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://lore.kernel.org/r/20221027155908.1940624-4-ardb@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/kernel/head.S')
| -rw-r--r-- | arch/arm64/kernel/head.S | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 2196aad7b55b..952e17bd1c0b 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -462,6 +462,9 @@ SYM_FUNC_START_LOCAL(__primary_switched) bl early_fdt_map // Try mapping the FDT early mov x0, x20 // pass the full boot status bl init_feature_override // Parse cpu feature overrides +#ifdef CONFIG_UNWIND_PATCH_PAC_INTO_SCS + bl scs_patch_vmlinux +#endif mov x0, x20 bl finalise_el2 // Prefer VHE if possible ldp x29, x30, [sp], #16 |