linux-kernel - [PATCH 4.19 039/287] arm64: Do not forget syscall when starting a new thread.

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Date:   Tue, 23 Aug 2022 10:23:28 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Francis Laniel <flaniel@...ux.microsoft.com>,
        Will Deacon <will@...nel.org>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 039/287] arm64: Do not forget syscall when starting a new thread.

From: Francis Laniel <flaniel@...ux.microsoft.com>

[ Upstream commit de6921856f99c11d3986c6702d851e1328d4f7f6 ]

Enable tracing of the execve*() system calls with the
syscalls:sys_exit_execve tracepoint by removing the call to
forget_syscall() when starting a new thread and preserving the value of
regs->syscallno across exec.

Signed-off-by: Francis Laniel <flaniel@...ux.microsoft.com>
Link: https://lore.kernel.org/r/20220608162447.666494-2-flaniel@linux.microsoft.com
Signed-off-by: Will Deacon <will@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/arm64/include/asm/processor.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index 773ea8e0e442..f81074c68ff3 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -172,8 +172,9 @@ void tls_preserve_current_state(void);
 
 static inline void start_thread_common(struct pt_regs *regs, unsigned long pc)
 {
+	s32 previous_syscall = regs->syscallno;
 	memset(regs, 0, sizeof(*regs));
-	forget_syscall(regs);
+	regs->syscallno = previous_syscall;
 	regs->pc = pc;
 }
 
-- 
2.35.1