From 6e307a6d9eb4d38298b7c9f4160e975e91e832b0 Mon Sep 17 00:00:00 2001 From: Alexandre Ghiti Date: Tue, 26 Mar 2024 21:30:17 +0100 Subject: [PATCH] riscv: Disable preemption when using patch_map() [ Upstream commit a370c2419e4680a27382d9231edcf739d5d74efc ] 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 Signed-off-by: Sasha Levin --- arch/riscv/kernel/patch.c | 8 ++++++++ 1 file changed, 8 insertions(+) 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);