Refactor syscall_trace_enter() and syscall_trace_exit() to move thread flag reading to the caller and adopt standard helpers. This aligns arm64's internal tracing logic with the requirements of the generic entry framework. [Changes] 1. Function signature changes: - syscall_trace_enter(regs) → syscall_trace_enter(regs, flags) - syscall_trace_exit(regs) → syscall_trace_exit(regs, flags) 2. Move flags reading to caller: - Previously: read_thread_flags() called inside each function. - Now: caller (like el0_svc_common) passes flags as parameter. - Benefit: Avoids redundant flag reading and simplifies the interface. 3. Use syscall_get_nr() helper: - Replace direct regs->syscallno access with syscall_get_nr(current, regs). - This helper is functionally equivalent to direct access on arm64. 4. Re-read syscall number after tracepoint: - Re-fetch the syscall number after trace_sys_enter() as it may have been modified by BPF or ftrace probes, matching generic entry behavior. 5. Update syscall.c: - el0_svc_common() now passes flags to tracing functions and re-fetches flags before exit to handle potential TIF updates. [Why this matters] - Aligns arm64 with the generic entry interface. - Makes future migration to generic entry framework. - Properly handles syscall number modifications by tracers. - Uses standard architecture-independent helpers. No functional changes intended. Cc: Will Deacon <will@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com> --- arch/arm64/include/asm/syscall.h | 4 ++-- arch/arm64/kernel/ptrace.c | 26 +++++++++++++++++--------- arch/arm64/kernel/syscall.c | 5 +++-- 3 files changed, 22 insertions(+), 13 deletions(-) diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h index 5e4c7fc44f73..30b203ef156b 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, 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 ba5eab23fd90..8d296a07fbf7 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -2408,9 +2408,9 @@ 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, unsigned long flags) { - unsigned long flags = read_thread_flags(); + long syscall; int ret; if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) { @@ -2423,19 +2423,27 @@ 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; } -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 c062badd1a56..e8fd0d60ab09 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, 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) -- 2.34.1