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Mon, 8 Dec 2025 14:24:44 +0800 (CST) Received: from [10.67.109.254] (10.67.109.254) by dggpemf500011.china.huawei.com (7.185.36.131) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Mon, 8 Dec 2025 14:24:42 +0800 Message-ID: <9102697c-9159-395d-e1b5-78439aa5a8b9@huawei.com> Date: Mon, 8 Dec 2025 14:24:41 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.2.0 Subject: Re: [PATCH v9 04/16] arm64/ptrace: Refactor syscall_trace_enter/exit() Content-Language: en-US To: Anshuman Khandual , , , , , , , , , , , , , , , , , , , , , , , , References: <20251204082123.2792067-1-ruanjinjie@huawei.com> <20251204082123.2792067-5-ruanjinjie@huawei.com> From: Jinjie Ruan In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.109.254] X-ClientProxiedBy: kwepems100001.china.huawei.com (7.221.188.238) To dggpemf500011.china.huawei.com (7.185.36.131) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251207_222454_704881_443D010B X-CRM114-Status: GOOD ( 14.33 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2025/12/8 13:48, Anshuman Khandual wrote: > On 04/12/25 1:51 PM, Jinjie Ruan wrote: >> The generic syscall entry code has the following form, which use >> the input syscall work flag and syscall number: >> >> | syscall_trace_enter(struct pt_regs *regs, long syscall, >> | unsigned long work) >> | >> | syscall_exit_work(struct pt_regs *regs, unsigned long work) >> >> In preparation for moving arm64 over to the generic entry code, >> refactor syscall_trace_enter/exit() to also pass thread flags, and >> get syscall number by syscall_get_nr() helper. >> >> No functional changes. >> >> Reviewed-by: Kevin Brodsky >> Signed-off-by: Jinjie Ruan >> --- >> arch/arm64/include/asm/syscall.h | 4 ++-- >> arch/arm64/kernel/ptrace.c | 25 ++++++++++++++++--------- >> arch/arm64/kernel/syscall.c | 5 +++-- >> 3 files changed, 21 insertions(+), 13 deletions(-) >> >> diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h >> index 5e4c7fc44f73..cef1d9ce6e1b 100644 >> --- a/arch/arm64/include/asm/syscall.h >> +++ b/arch/arm64/include/asm/syscall.h >> @@ -120,7 +120,7 @@ static inline int syscall_get_arch(struct task_struct *task) >> return AUDIT_ARCH_AARCH64; >> } >> >> -int syscall_trace_enter(struct pt_regs *regs); >> -void syscall_trace_exit(struct pt_regs *regs); >> +int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags); >> +void syscall_trace_exit(struct pt_regs *regs, unsigned long flags); >> >> #endif /* __ASM_SYSCALL_H */ >> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c >> index 3926ce6aa268..b962cbcca11d 100644 >> --- a/arch/arm64/kernel/ptrace.c >> +++ b/arch/arm64/kernel/ptrace.c >> @@ -2381,9 +2381,8 @@ static void report_syscall_exit(struct pt_regs *regs) >> } >> } >> >> -int syscall_trace_enter(struct pt_regs *regs) >> +int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags) >> { >> - unsigned long flags = read_thread_flags(); >> int ret; >> >> if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) { >> @@ -2396,19 +2395,27 @@ int syscall_trace_enter(struct pt_regs *regs) >> if (secure_computing() == -1) >> return NO_SYSCALL; >> >> - if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) >> - trace_sys_enter(regs, regs->syscallno); >> + /* Either of the above might have changed the syscall number */ >> + syscall = syscall_get_nr(current, regs); >> >> - audit_syscall_entry(regs->syscallno, regs->orig_x0, regs->regs[1], >> + if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) { >> + trace_sys_enter(regs, syscall); >> + >> + /* >> + * Probes or BPF hooks in the tracepoint may have changed the >> + * system call number as well. >> + */ >> + syscall = syscall_get_nr(current, regs); >> + } >> + >> + audit_syscall_entry(syscall, regs->orig_x0, regs->regs[1], >> regs->regs[2], regs->regs[3]); >> >> - return regs->syscallno; >> + return syscall; > > regs->syscallno still remains unchanged even if syscall is evaluated to be different ? No, arm64 syscall_get_nr() returns regs->syscallno, use syscall_get_nr() helper here to get the local "syscall" is to stay consistent with the generic entry, without any semantic change. 23 static inline int syscall_get_nr(struct task_struct *task, 24 >------->------->------->------- struct pt_regs *regs) 25 { 26 >-------return regs->syscallno; 27 } > >> } >> >> -void syscall_trace_exit(struct pt_regs *regs) >> +void syscall_trace_exit(struct pt_regs *regs, unsigned long flags) >> { >> - unsigned long flags = read_thread_flags(); >> - >> audit_syscall_exit(regs); >> >> if (flags & _TIF_SYSCALL_TRACEPOINT) >> diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c >> index aba7ca6bca2d..ec31f82d2e9f 100644 >> --- a/arch/arm64/kernel/syscall.c >> +++ b/arch/arm64/kernel/syscall.c >> @@ -124,7 +124,7 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr, >> */ >> if (scno == NO_SYSCALL) >> syscall_set_return_value(current, regs, -ENOSYS, 0); >> - scno = syscall_trace_enter(regs); >> + scno = syscall_trace_enter(regs, scno, flags); >> if (scno == NO_SYSCALL) >> goto trace_exit; >> } >> @@ -143,7 +143,8 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr, >> } >> >> trace_exit: >> - syscall_trace_exit(regs); >> + flags = read_thread_flags(); >> + syscall_trace_exit(regs, flags); >> } >> >> void do_el0_svc(struct pt_regs *regs) > >