Use syscall_get_nr() to get syscall number for syscall_trace_enter().
This aligns arm64's internal tracing logic with the generic
entry framework.
[Changes]
1. 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.
2. 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.
[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 <[email protected]>
Cc: Catalin Marinas <[email protected]>
Reviewed-by: Kevin Brodsky <[email protected]>
Signed-off-by: Jinjie Ruan <[email protected]>
---
arch/arm64/kernel/ptrace.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index e4d524ccbc7b..8d296a07fbf7 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -2410,6 +2410,7 @@ static void report_syscall_exit(struct pt_regs *regs)
int syscall_trace_enter(struct pt_regs *regs, unsigned long flags)
{
+ long syscall;
int ret;
if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {
@@ -2422,13 +2423,23 @@ int syscall_trace_enter(struct pt_regs *regs, unsigned
long flags)
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, unsigned long flags)
--
2.34.1
