[PATCH 5.15 437/731] RISC-V: Align the shadow stack

Greg Kroah-Hartman
2022-12-28T15:24:58Z

From: Palmer Dabbelt <palmer@rivosinc.com>

[ Upstream commit b003b3b77d65133a0011ae3b7b255347438c12f6 ]

The standard RISC-V ABIs all require 16-byte stack alignment. We're
only calling that one function on the shadow stack so I doubt it'd
result in a real issue, but might as well keep this lined up.

Fixes: 31da94c25aea ("riscv: add VMAP_STACK overflow detection")
Reviewed-by: Jisheng Zhang <jszhang@kernel.org>
Link: https://lore.kernel.org/r/20221130023515.20217-1-palmer@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/riscv/kernel/traps.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
index 2f4cd85fb651..4102c97309cc 100644
--- a/arch/riscv/kernel/traps.c
+++ b/arch/riscv/kernel/traps.c
@@ -211,7 +211,7 @@ static DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)],
* shadow stack, handled_ kernel_ stack_ overflow(in kernel/entry.S) is used
* to get per-cpu overflow stack(get_overflow_stack).
*/
-long shadow_stack[SHADOW_OVERFLOW_STACK_SIZE/sizeof(long)];
+long shadow_stack[SHADOW_OVERFLOW_STACK_SIZE/sizeof(long)] __aligned(16);
asmlinkage unsigned long get_overflow_stack(void)
{
return (unsigned long)this_cpu_ptr(overflow_stack) +
--
2.35.1