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[141.95.202.232]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-74ce43d4f1asm10877511b3a.161.2025.07.08.01.34.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Jul 2025 01:34:47 -0700 (PDT) From: Alexandre Ghiti Date: Tue, 08 Jul 2025 08:33:48 +0000 Subject: [PATCH] riscv: ftrace: Properly acquire text_mutex to fix a race condition Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250708-alex-fixes-v1-1-5b008d3f4d0c@rivosinc.com> X-B4-Tracking: v=1; b=H4sIAOzXbGgC/x2LQQqAIBAAvyJ7TlAj1L4SHazWWggLF0II/550H GbmBcZMyDCKFzI+xHSlBroTsB4h7ShpawxGmUFZ5WQ4schIBVlqtNov3nkfe2jDnfEXrZ/mWj+ cWU9oXAAAAA== X-Change-ID: 20250708-alex-fixes-1e719b9899f3 To: Steven Rostedt , Masami Hiramatsu , Mark Rutland , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, Han Gao , Vivian Wang , Yao Zi , Alexandre Ghiti X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=2192; i=alexghiti@rivosinc.com; h=from:subject:message-id; bh=3Ds2Sx45pnkMg7iaFweDgWNlUOwHGzX5GUkhgeYgbzQ=; b=owGbwMvMwCGWYr9pz6TW912Mp9WSGDJybqi8ChN0klf9crq7b8aPt753f26W6d7Q/lf4XIly/ tbNVWHHOkpZGMQ4GGTFFFkUzBO6WuzP1s/+c+k9zBxWJpAhDFycAjARhkcM/71fRb1avvPr6cDQ 57eWZxy+GdJybW8Tt0THf0umRv+l5qsYGe4fuN+4spx9reHpB0yRSob6tk+dHI13b2m5sXtL/ql 4LV4A X-Developer-Key: i=alexghiti@rivosinc.com; a=openpgp; fpr=DC049C97114ED82152FE79A783E4BA75438E93E3 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 Reported-by: Vivian Wang Reported-by: Yao Zi Closes: https://lore.kernel.org/linux-riscv/aGODMpq7TGINddzM@pie.lan/ Tested-by: Yao Zi Signed-off-by: Alexandre Ghiti Reviewed-by: Andy Chiu Reviewed-by: Masami Hiramatsu (Google) Tested-by: Han Gao --- 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..22e7bdf8de2b6ca950cf2c8b734= bc82ea46ba8bf 100644 --- a/arch/riscv/kernel/ftrace.c +++ b/arch/riscv/kernel/ftrace.c @@ -14,6 +14,16 @@ #include =20 #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 fent= ry_ip) =20 void arch_ftrace_update_code(int command) { - mutex_lock(&text_mutex); command |=3D FTRACE_MAY_SLEEP; ftrace_modify_all_code(command); - mutex_unlock(&text_mutex); flush_icache_all(); } =20 @@ -149,6 +157,8 @@ int ftrace_init_nop(struct module *mod, struct dyn_ftra= ce *rec) unsigned int nops[2], offset; int ret; =20 + guard(mutex)(&text_mutex); + ret =3D ftrace_rec_set_nop_ops(rec); if (ret) return ret; @@ -157,9 +167,7 @@ int ftrace_init_nop(struct module *mod, struct dyn_ftra= ce *rec) nops[0] =3D to_auipc_t0(offset); nops[1] =3D RISCV_INSN_NOP4; =20 - mutex_lock(&text_mutex); ret =3D patch_insn_write((void *)pc, nops, 2 * MCOUNT_INSN_SIZE); - mutex_unlock(&text_mutex); =20 return ret; } --- base-commit: d7b8f8e20813f0179d8ef519541a3527e7661d3a change-id: 20250708-alex-fixes-1e719b9899f3 Best regards, --=20 Alexandre Ghiti