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| author | Sami Tolvanen <samitolvanen@google.com> | 2023-09-27 22:48:02 +0000 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@rivosinc.com> | 2023-10-27 14:43:08 -0700 |
| commit | d1584d791a297aa8ed93503382a682a6ecfc4218 (patch) | |
| tree | 371b56adbd1d77f436e143555ab9fb47b4ad50c0 /arch/riscv/include/asm/asm.h | |
| parent | e609b4f4252a2ad2454736078693571b9fbff019 (diff) | |
| download | lwn-d1584d791a297aa8ed93503382a682a6ecfc4218.tar.gz lwn-d1584d791a297aa8ed93503382a682a6ecfc4218.zip | |
riscv: Implement Shadow Call Stack
Implement CONFIG_SHADOW_CALL_STACK for RISC-V. When enabled, the
compiler injects instructions to all non-leaf C functions to
store the return address to the shadow stack and unconditionally
load it again before returning, which makes it harder to corrupt
the return address through a stack overflow, for example.
The active shadow call stack pointer is stored in the gp
register, which makes SCS incompatible with gp relaxation. Use
--no-relax-gp to ensure gp relaxation is disabled and disable
global pointer loading. Add SCS pointers to struct thread_info,
implement SCS initialization, and task switching
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20230927224757.1154247-12-samitolvanen@google.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Diffstat (limited to 'arch/riscv/include/asm/asm.h')
| -rw-r--r-- | arch/riscv/include/asm/asm.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/riscv/include/asm/asm.h b/arch/riscv/include/asm/asm.h index f34dd1a526a1..b0487b39e674 100644 --- a/arch/riscv/include/asm/asm.h +++ b/arch/riscv/include/asm/asm.h @@ -109,6 +109,11 @@ REG_L \dst, 0(\dst) .endm +#ifdef CONFIG_SHADOW_CALL_STACK +/* gp is used as the shadow call stack pointer instead */ +.macro load_global_pointer +.endm +#else /* load __global_pointer to gp */ .macro load_global_pointer .option push @@ -116,6 +121,7 @@ la gp, __global_pointer$ .option pop .endm +#endif /* CONFIG_SHADOW_CALL_STACK */ /* save all GPs except x1 ~ x5 */ .macro save_from_x6_to_x31 |