* Re: [PATCH] riscv: ftrace: Properly acquire text_mutex to fix a race condition
2025-07-08 8:33 [PATCH] riscv: ftrace: Properly acquire text_mutex to fix a race condition Alexandre Ghiti
@ 2025-07-09 14:12 ` Palmer Dabbelt
2025-07-09 16:45 ` Steven Rostedt
2025-07-10 0:06 ` Masami Hiramatsu
` (2 subsequent siblings)
3 siblings, 1 reply; 7+ messages in thread
From: Palmer Dabbelt @ 2025-07-09 14:12 UTC (permalink / raw)
To: alexghiti
Cc: rostedt, mhiramat, Mark Rutland, Paul Walmsley, aou,
Alexandre Ghiti, linux-kernel, linux-trace-kernel, linux-riscv,
rabenda.cn, wangruikang, ziyao, alexghiti
On Tue, 08 Jul 2025 01:33:48 PDT (-0700), alexghiti@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.cn@gmail.com>
> Reported-by: Vivian Wang <wangruikang@iscas.ac.cn>
> Reported-by: Yao Zi <ziyao@disroot.org>
> Closes: https://lore.kernel.org/linux-riscv/aGODMpq7TGINddzM@pie.lan/
> Tested-by: Yao Zi <ziyao@disroot.org>
> Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.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);
> +}
IIRC there's a reason we don't do it this way, we had (or had tried to)
have it before. It's been a while, though, and I'm just having some a
coffee so may I'm just wrong...
> 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,
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH] riscv: ftrace: Properly acquire text_mutex to fix a race condition
2025-07-09 14:12 ` Palmer Dabbelt
@ 2025-07-09 16:45 ` Steven Rostedt
2025-07-16 15:22 ` Palmer Dabbelt
0 siblings, 1 reply; 7+ messages in thread
From: Steven Rostedt @ 2025-07-09 16:45 UTC (permalink / raw)
To: Palmer Dabbelt
Cc: alexghiti, mhiramat, Mark Rutland, Paul Walmsley, aou,
Alexandre Ghiti, linux-kernel, linux-trace-kernel, linux-riscv,
rabenda.cn, wangruikang, ziyao
On Wed, 09 Jul 2025 07:12:47 -0700 (PDT)
Palmer Dabbelt <palmer@dabbelt.com> wrote:
> > #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);
> > +}
>
> IIRC there's a reason we don't do it this way, we had (or had tried to)
> have it before. It's been a while, though, and I'm just having some a
> coffee so may I'm just wrong...
Yes, because it caused issues with stop machine[1], but if you are no
longer using stop machine, this should be what you should do now.
[1] https://lore.kernel.org/all/20220310045454.672097-1-changbin.du@gmail.com/
-- Steve
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH] riscv: ftrace: Properly acquire text_mutex to fix a race condition
2025-07-09 16:45 ` Steven Rostedt
@ 2025-07-16 15:22 ` Palmer Dabbelt
0 siblings, 0 replies; 7+ messages in thread
From: Palmer Dabbelt @ 2025-07-16 15:22 UTC (permalink / raw)
To: rostedt
Cc: alexghiti, mhiramat, Mark Rutland, Paul Walmsley, aou,
Alexandre Ghiti, linux-kernel, linux-trace-kernel, linux-riscv,
rabenda.cn, wangruikang, ziyao
On Wed, 09 Jul 2025 09:45:36 PDT (-0700), rostedt@goodmis.org wrote:
> On Wed, 09 Jul 2025 07:12:47 -0700 (PDT)
> Palmer Dabbelt <palmer@dabbelt.com> wrote:
>
>> > #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);
>> > +}
>>
>> IIRC there's a reason we don't do it this way, we had (or had tried to)
>> have it before. It's been a while, though, and I'm just having some a
>> coffee so may I'm just wrong...
>
> Yes, because it caused issues with stop machine[1], but if you are no
> longer using stop machine, this should be what you should do now.
>
> [1] https://lore.kernel.org/all/20220310045454.672097-1-changbin.du@gmail.com/
Thanks. The v2 staged for the tester, should show up on fixes soon.
>
> -- Steve
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] riscv: ftrace: Properly acquire text_mutex to fix a race condition
2025-07-08 8:33 [PATCH] riscv: ftrace: Properly acquire text_mutex to fix a race condition Alexandre Ghiti
2025-07-09 14:12 ` Palmer Dabbelt
@ 2025-07-10 0:06 ` Masami Hiramatsu
2025-07-10 6:21 ` Han Gao
2025-07-11 10:00 ` Andy Chiu
3 siblings, 0 replies; 7+ messages in thread
From: Masami Hiramatsu @ 2025-07-10 0:06 UTC (permalink / raw)
To: Alexandre Ghiti
Cc: Steven Rostedt, Mark Rutland, Paul Walmsley, Palmer Dabbelt,
Albert Ou, Alexandre Ghiti, linux-kernel, linux-trace-kernel,
linux-riscv, Han Gao, Vivian Wang, Yao Zi
On Tue, 08 Jul 2025 08:33:48 +0000
Alexandre Ghiti <alexghiti@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.cn@gmail.com>
> Reported-by: Vivian Wang <wangruikang@iscas.ac.cn>
> Reported-by: Yao Zi <ziyao@disroot.org>
> Closes: https://lore.kernel.org/linux-riscv/aGODMpq7TGINddzM@pie.lan/
> Tested-by: Yao Zi <ziyao@disroot.org>
> Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.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)
To be sure this is acquire the text_mutex, add __acquires(&text_mutex) here.
> +{
> + mutex_lock(&text_mutex);
> +}
> +
> +void ftrace_arch_code_modify_post_process(void)
Ditto, add __releases(&text_mutex) here.
others looks good to me.
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Thanks,
> +{
> + 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 <alexghiti@rivosinc.com>
>
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH] riscv: ftrace: Properly acquire text_mutex to fix a race condition
2025-07-08 8:33 [PATCH] riscv: ftrace: Properly acquire text_mutex to fix a race condition Alexandre Ghiti
2025-07-09 14:12 ` Palmer Dabbelt
2025-07-10 0:06 ` Masami Hiramatsu
@ 2025-07-10 6:21 ` Han Gao
2025-07-11 10:00 ` Andy Chiu
3 siblings, 0 replies; 7+ messages in thread
From: Han Gao @ 2025-07-10 6:21 UTC (permalink / raw)
To: Alexandre Ghiti
Cc: Steven Rostedt, Masami Hiramatsu, Mark Rutland, Paul Walmsley,
Palmer Dabbelt, Albert Ou, Alexandre Ghiti, linux-kernel,
linux-trace-kernel, linux-riscv, Vivian Wang, Yao Zi
On Tue, Jul 8, 2025 at 4:34 PM Alexandre Ghiti <alexghiti@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.cn@gmail.com>
> Reported-by: Vivian Wang <wangruikang@iscas.ac.cn>
> Reported-by: Yao Zi <ziyao@disroot.org>
> Closes: https://lore.kernel.org/linux-riscv/aGODMpq7TGINddzM@pie.lan/
> Tested-by: Yao Zi <ziyao@disroot.org>
> Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Tested-by: Han Gao <rabenda.cn@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 <alexghiti@rivosinc.com>
>
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH] riscv: ftrace: Properly acquire text_mutex to fix a race condition
2025-07-08 8:33 [PATCH] riscv: ftrace: Properly acquire text_mutex to fix a race condition Alexandre Ghiti
` (2 preceding siblings ...)
2025-07-10 6:21 ` Han Gao
@ 2025-07-11 10:00 ` Andy Chiu
3 siblings, 0 replies; 7+ messages in thread
From: Andy Chiu @ 2025-07-11 10:00 UTC (permalink / raw)
To: Alexandre Ghiti
Cc: Steven Rostedt, Masami Hiramatsu, Mark Rutland, Paul Walmsley,
Palmer Dabbelt, Albert Ou, Alexandre Ghiti, linux-kernel,
linux-trace-kernel, linux-riscv, Han Gao, Vivian Wang, Yao Zi
On Tue, Jul 8, 2025 at 4:47 PM Alexandre Ghiti <alexghiti@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.cn@gmail.com>
> Reported-by: Vivian Wang <wangruikang@iscas.ac.cn>
> Reported-by: Yao Zi <ziyao@disroot.org>
> Closes: https://lore.kernel.org/linux-riscv/aGODMpq7TGINddzM@pie.lan/
> Tested-by: Yao Zi <ziyao@disroot.org>
> Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Andy Chiu <andybnac@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 <alexghiti@rivosinc.com>
>
>
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 7+ messages in thread