diff options
Diffstat (limited to 'arch/riscv/kernel/patch.c')
| -rw-r--r-- | arch/riscv/kernel/patch.c | 28 |
1 files changed, 25 insertions, 3 deletions
diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c index 8086d1a281cd..575e71d6c8ae 100644 --- a/arch/riscv/kernel/patch.c +++ b/arch/riscv/kernel/patch.c @@ -11,6 +11,7 @@ #include <asm/kprobes.h> #include <asm/cacheflush.h> #include <asm/fixmap.h> +#include <asm/ftrace.h> #include <asm/patch.h> struct patch_insn { @@ -20,6 +21,8 @@ struct patch_insn { atomic_t cpu_count; }; +int riscv_patch_in_stop_machine = false; + #ifdef CONFIG_MMU /* * The fix_to_virt(, idx) needs a const value (not a dynamic variable of @@ -60,8 +63,15 @@ static int patch_insn_write(void *addr, const void *insn, size_t len) * Before reaching here, it was expected to lock the text_mutex * already, so we don't need to give another lock here and could * ensure that it was safe between each cores. + * + * We're currently using stop_machine() for ftrace & kprobes, and while + * that ensures text_mutex is held before installing the mappings it + * does not ensure text_mutex is held by the calling thread. That's + * safe but triggers a lockdep failure, so just elide it for that + * specific case. */ - lockdep_assert_held(&text_mutex); + if (!riscv_patch_in_stop_machine) + lockdep_assert_held(&text_mutex); if (across_pages) patch_map(addr + len, FIX_TEXT_POKE1); @@ -125,6 +135,7 @@ NOKPROBE_SYMBOL(patch_text_cb); int patch_text(void *addr, u32 *insns, int ninsns) { + int ret; struct patch_insn patch = { .addr = addr, .insns = insns, @@ -132,7 +143,18 @@ int patch_text(void *addr, u32 *insns, int ninsns) .cpu_count = ATOMIC_INIT(0), }; - return stop_machine_cpuslocked(patch_text_cb, - &patch, cpu_online_mask); + /* + * kprobes takes text_mutex, before calling patch_text(), but as we call + * calls stop_machine(), the lockdep assertion in patch_insn_write() + * gets confused by the context in which the lock is taken. + * Instead, ensure the lock is held before calling stop_machine(), and + * set riscv_patch_in_stop_machine to skip the check in + * patch_insn_write(). + */ + lockdep_assert_held(&text_mutex); + riscv_patch_in_stop_machine = true; + ret = stop_machine_cpuslocked(patch_text_cb, &patch, cpu_online_mask); + riscv_patch_in_stop_machine = false; + return ret; } NOKPROBE_SYMBOL(patch_text); |