From: Alexandre Ghiti Date: Tue, 26 Mar 2024 20:30:17 +0000 (+0100) Subject: riscv: Disable preemption when using patch_map() X-Git-Tag: Ubuntu-6.11.0-9.9~1758^2~1 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=a370c2419e4680a27382d9231edcf739d5d74efc;p=mirror_ubuntu-kernels.git riscv: Disable preemption when using patch_map() patch_map() uses fixmap mappings to circumvent the non-writability of the kernel text mapping. The __set_fixmap() function only flushes the current cpu tlb, it does not emit an IPI so we must make sure that while we use a fixmap mapping, the current task is not migrated on another cpu which could miss the newly introduced fixmap mapping. So in order to avoid any task migration, disable the preemption. Reported-by: Andrea Parri Closes: https://lore.kernel.org/all/ZcS+GAaM25LXsBOl@andrea/ Reported-by: Andy Chiu Closes: https://lore.kernel.org/linux-riscv/CABgGipUMz3Sffu-CkmeUB1dKVwVQ73+7=sgC45-m0AE9RCjOZg@mail.gmail.com/ Fixes: cad539baa48f ("riscv: implement a memset like function for text") Fixes: 0ff7c3b33127 ("riscv: Use text_mutex instead of patch_lock") Co-developed-by: Andy Chiu Signed-off-by: Andy Chiu Signed-off-by: Alexandre Ghiti Acked-by: Puranjay Mohan Link: https://lore.kernel.org/r/20240326203017.310422-3-alexghiti@rivosinc.com Signed-off-by: Palmer Dabbelt --- diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c index 37e87fdcf6a0..30e12b310cab 100644 --- a/arch/riscv/kernel/patch.c +++ b/arch/riscv/kernel/patch.c @@ -80,6 +80,8 @@ static int __patch_insn_set(void *addr, u8 c, size_t len) */ lockdep_assert_held(&text_mutex); + preempt_disable(); + if (across_pages) patch_map(addr + PAGE_SIZE, FIX_TEXT_POKE1); @@ -92,6 +94,8 @@ static int __patch_insn_set(void *addr, u8 c, size_t len) if (across_pages) patch_unmap(FIX_TEXT_POKE1); + preempt_enable(); + return 0; } NOKPROBE_SYMBOL(__patch_insn_set); @@ -122,6 +126,8 @@ static int __patch_insn_write(void *addr, const void *insn, size_t len) if (!riscv_patch_in_stop_machine) lockdep_assert_held(&text_mutex); + preempt_disable(); + if (across_pages) patch_map(addr + PAGE_SIZE, FIX_TEXT_POKE1); @@ -134,6 +140,8 @@ static int __patch_insn_write(void *addr, const void *insn, size_t len) if (across_pages) patch_unmap(FIX_TEXT_POKE1); + preempt_enable(); + return ret; } NOKPROBE_SYMBOL(__patch_insn_write);