diff options
| author | Palmer Dabbelt <palmer@rivosinc.com> | 2022-12-12 20:30:37 +0300 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@rivosinc.com> | 2022-12-12 20:30:37 +0300 |
| commit | c3ec1e8964fb0ca00c79936160a027bd8b47e140 (patch) | |
| tree | a9391a50f9c9205a87244dbfae6519b7774bddb6 /arch/riscv/kernel/entry.S | |
| parent | d01404fa7b8c72c7052232423f30a16060828f28 (diff) | |
| parent | de57ecc476103179e93fd85091770921f76a19af (diff) | |
| download | linux-c3ec1e8964fb0ca00c79936160a027bd8b47e140.tar.xz | |
Merge patch series "RISC-V: Align the shadow stack"
Palmer Dabbelt <palmer@rivosinc.com> says:
This contains a pair of cleanups that depend on a fix that has already
landed upstream.
* b4-shazam-merge:
RISC-V: Add some comments about the shadow and overflow stacks
RISC-V: Align the shadow stack
riscv: fix race when vmap stack overflow
Link: https://lore.kernel.org/r/20221130023515.20217-1-palmer@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Diffstat (limited to 'arch/riscv/kernel/entry.S')
| -rw-r--r-- | arch/riscv/kernel/entry.S | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index 32b2ddafedb0..99d38fdf8b18 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -397,6 +397,19 @@ handle_syscall_trace_exit: #ifdef CONFIG_VMAP_STACK handle_kernel_stack_overflow: + /* + * Takes the psuedo-spinlock for the shadow stack, in case multiple + * harts are concurrently overflowing their kernel stacks. We could + * store any value here, but since we're overflowing the kernel stack + * already we only have SP to use as a scratch register. So we just + * swap in the address of the spinlock, as that's definately non-zero. + * + * Pairs with a store_release in handle_bad_stack(). + */ +1: la sp, spin_shadow_stack + REG_AMOSWAP_AQ sp, sp, (sp) + bnez sp, 1b + la sp, shadow_stack addi sp, sp, SHADOW_OVERFLOW_STACK_SIZE |