[PATCH -next v5 13/22] arm64/ptrace: Refactor syscall_trace_enter()

[Jinjie Ruan <ruanjinjie@xxxxxxxxxx>]

The generic entry syscall_trace_enter() use the input syscall
work flag and syscall number.

In preparation for moving arm64 over to the generic entry code, refactor
syscall_trace_enter() to also pass syscall number and thread flags,
by using syscall_get_nr() helper.

No functional changes.

Signed-off-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
---
 arch/arm64/include/asm/syscall.h |  2 +-
 arch/arm64/kernel/ptrace.c       | 20 ++++++++++++++------
 arch/arm64/kernel/syscall.c      |  2 +-
 3 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
index ab8e14b96f68..6b71d335c224 100644
--- a/arch/arm64/include/asm/syscall.h
+++ b/arch/arm64/include/asm/syscall.h
@@ -85,7 +85,7 @@ static inline int syscall_get_arch(struct task_struct *task)
        return AUDIT_ARCH_AARCH64;
 }
 
-int syscall_trace_enter(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);
 
 #endif /* __ASM_SYSCALL_H */
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index d0d801a4094a..48bb813e0ef6 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -2353,10 +2353,8 @@ 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();
-
        if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {
                report_syscall_enter(regs);
                if (flags & _TIF_SYSCALL_EMU)
@@ -2367,10 +2365,20 @@ 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);
+
+       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(regs->syscallno, regs->orig_x0, regs->regs[1],
+       audit_syscall_entry(syscall, regs->orig_x0, regs->regs[1],
                            regs->regs[2], regs->regs[3]);
 
        return regs->syscallno;
diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
index c442fcec6b9e..eb328ee1423c 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, regs->syscallno, flags);
                if (scno == NO_SYSCALL)
                        goto trace_exit;
        }
-- 
2.34.1