[PATCH v17 07/15] arm64: ptrace: Pass thread flags to trace enter/exit

[Jinjie Ruan]

Move the reading of thread flags from inside arm64_syscall_trace_enter()
and syscall_trace_exit() to their callers.  This aligns the function
signatures with the generic entry framework, where the caller
is responsible for supplying the flags.

In el0_svc_common(), the flags are now passed directly to the tracing
functions, and re-read before the enter/exit path to reflect any updates.

No functional change intended; this is a preparatory step for
converting arm64 to the generic entry infrastructure.

Cc: Mark Rutland <mark.rutland at arm.com>
Cc: Will Deacon <will at kernel.org>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Reviewed-by: Ada Couprie Diaz <ada.coupriediaz at arm.com>
Reviewed-by: Linus Walleij <linusw at kernel.org>
Reviewed-by: Yeoreum Yun <yeoreum.yun at arm.com>
Reviewed-by: Kevin Brodsky <kevin.brodsky at arm.com>
Signed-off-by: Jinjie Ruan <ruanjinjie at huawei.com>
---
 arch/arm64/include/asm/syscall.h |  4 ++--
 arch/arm64/kernel/ptrace.c       |  6 ++----
 arch/arm64/kernel/syscall.c      | 11 +++++++----
 3 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
index d1dabdcde41c..696739f5a250 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 arm64_syscall_trace_enter(struct pt_regs *regs);
-void syscall_trace_exit(struct pt_regs *regs);
+int arm64_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 a7091333a9e9..18fa29ae1425 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -2469,9 +2469,8 @@ static inline void syscall_enter_audit(struct pt_regs *regs)
 }
 #endif
 
-int arm64_syscall_trace_enter(struct pt_regs *regs)
+int arm64_syscall_trace_enter(struct pt_regs *regs, unsigned long flags)
 {
-	unsigned long flags = read_thread_flags();
 	int ret;
 
 	if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {
@@ -2506,9 +2505,8 @@ static inline bool report_single_step(unsigned long flags)
 	return flags & _TIF_SINGLESTEP;
 }
 
-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();
 	bool step;
 
 	rseq_syscall(regs);
diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
index b8d7d29a431b..e778aac6fab9 100644
--- a/arch/arm64/kernel/syscall.c
+++ b/arch/arm64/kernel/syscall.c
@@ -113,7 +113,7 @@ 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 = arm64_syscall_trace_enter(regs);
+		scno = arm64_syscall_trace_enter(regs, read_thread_flags());
 		if (scno == NO_SYSCALL)
 			goto trace_exit;
 	}
@@ -127,13 +127,16 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
 	 */
 	if (!has_syscall_work(flags) && !IS_ENABLED(CONFIG_DEBUG_RSEQ)) {
 		flags = read_thread_flags();
-		if (has_syscall_work(flags) || flags & _TIF_SINGLESTEP)
-			syscall_trace_exit(regs);
+		if (has_syscall_work(flags) || flags & _TIF_SINGLESTEP) {
+			flags = read_thread_flags();
+			syscall_trace_exit(regs, flags);
+		}
 		return;
 	}
 
 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