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| author | Palmer Dabbelt <palmer@rivosinc.com> | 2022-12-01 11:38:39 -0800 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@rivosinc.com> | 2022-12-01 11:38:39 -0800 |
| commit | 39cefc5f6cd25d555e0455b24810e9aff365b8d6 (patch) | |
| tree | 3f5ae903747a2bec6fab24ea9de151ddbdf766cf /arch/riscv/kernel/entry.S | |
| parent | d556a9aeb62a6cd44aa05aeadcc48245da0a1939 (diff) | |
| parent | 7e1864332fbc1b993659eab7974da9fe8bf8c128 (diff) | |
| download | linux-39cefc5f6cd25d555e0455b24810e9aff365b8d6.tar.gz | |
RISC-V: Fix a race condition during kernel stack overflow
This fixes a concrete bug but is also the basis for some cleanup work,
so I'm merging it based on the offending commit in order to minimize
future conflicts.
* commit '7e1864332fbc1b993659eab7974da9fe8bf8c128':
riscv: fix race when vmap stack overflow
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 b9eda3fcbd6d..186abd146eaf 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -404,6 +404,19 @@ 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 |