On Tue, Jul 8, 2025 at 4:47 PM Alexandre Ghiti <alexgh...@rivosinc.com> wrote:
>
> As reported by lockdep, some patching was done without acquiring
> text_mutex, so there could be a race when mapping the page to patch
> since we use the same fixmap entry.
>
> Reported-by: Han Gao <rabenda...@gmail.com>
> Reported-by: Vivian Wang <wangruik...@iscas.ac.cn>
> Reported-by: Yao Zi <zi...@disroot.org>
> Closes: https://lore.kernel.org/linux-riscv/agodmpq7tgind...@pie.lan/
> Tested-by: Yao Zi <zi...@disroot.org>
> Signed-off-by: Alexandre Ghiti <alexgh...@rivosinc.com>
Reviewed-by: Andy Chiu <andyb...@gmail.com>
> ---
> arch/riscv/kernel/ftrace.c | 16 ++++++++++++----
> 1 file changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c
> index
> 4c6c24380cfd9d6c51f0e4340cd674160b83a610..22e7bdf8de2b6ca950cf2c8b734bc82ea46ba8bf
> 100644
> --- a/arch/riscv/kernel/ftrace.c
> +++ b/arch/riscv/kernel/ftrace.c
> @@ -14,6 +14,16 @@
> #include <asm/text-patching.h>
>
> #ifdef CONFIG_DYNAMIC_FTRACE
> +void ftrace_arch_code_modify_prepare(void)
> +{
> + mutex_lock(&text_mutex);
> +}
> +
> +void ftrace_arch_code_modify_post_process(void)
> +{
> + mutex_unlock(&text_mutex);
> +}
> +
> unsigned long ftrace_call_adjust(unsigned long addr)
> {
> if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS))
> @@ -29,10 +39,8 @@ unsigned long arch_ftrace_get_symaddr(unsigned long
> fentry_ip)
>
> void arch_ftrace_update_code(int command)
> {
> - mutex_lock(&text_mutex);
> command |= FTRACE_MAY_SLEEP;
> ftrace_modify_all_code(command);
> - mutex_unlock(&text_mutex);
> flush_icache_all();
> }
>
> @@ -149,6 +157,8 @@ int ftrace_init_nop(struct module *mod, struct dyn_ftrace
> *rec)
> unsigned int nops[2], offset;
> int ret;
>
> + guard(mutex)(&text_mutex);
> +
> ret = ftrace_rec_set_nop_ops(rec);
> if (ret)
> return ret;
> @@ -157,9 +167,7 @@ int ftrace_init_nop(struct module *mod, struct dyn_ftrace
> *rec)
> nops[0] = to_auipc_t0(offset);
> nops[1] = RISCV_INSN_NOP4;
>
> - mutex_lock(&text_mutex);
> ret = patch_insn_write((void *)pc, nops, 2 * MCOUNT_INSN_SIZE);
> - mutex_unlock(&text_mutex);
>
> return ret;
> }
>
> ---
> base-commit: d7b8f8e20813f0179d8ef519541a3527e7661d3a
> change-id: 20250708-alex-fixes-1e719b9899f3
>
> Best regards,
> --
> Alexandre Ghiti <alexgh...@rivosinc.com>
>
>
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