From: Will Deacon <will@kernel.org>

Date: Fri, 10 Jul 2020 13:20:57 +0100

Subject: arm64: ptrace: Use NO_SYSCALL instead of -1 in syscall_trace_enter()

Git-commit: d83ee6e3e75db6f518ef2b0858f163849f2ddeb7

Patch-mainline: v5.8-rc6

References: git-fixes

Setting a system call number of -1 is special, as it indicates that the

current system call should be skipped.

Use NO_SYSCALL instead of -1 when checking for this scenario, which is

different from the -1 returned due to a seccomp failure.

Cc: Mark Rutland <mark.rutland@arm.com>

Cc: Keno Fischer <keno@juliacomputing.com>

Cc: Luis Machado <luis.machado@linaro.org>

Signed-off-by: Will Deacon <will@kernel.org>

Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>

---

 arch/arm64/kernel/ptrace.c |    4 ++--

 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/arm64/kernel/ptrace.c

+++ b/arch/arm64/kernel/ptrace.c

@@ -1834,12 +1834,12 @@ int syscall_trace_enter(struct pt_regs *

 	if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {

 		tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);

 		if (!in_syscall(regs) || (flags & _TIF_SYSCALL_EMU))

-			return -1;

+			return NO_SYSCALL;

 	}

 	/* Do the secure computing after ptrace; failures should be fast. */

 	if (secure_computing(NULL) == -1)

-		return -1;

+		return NO_SYSCALL;

 	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))

 		trace_sys_enter(regs, regs->syscallno);