Patch "arm64: Do not forget syscall when starting a new thread." has been added to the 4.19-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    arm64: Do not forget syscall when starting a new thread.

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     arm64-do-not-forget-syscall-when-starting-a-new-thre.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 38676cb1bab28bee0e459c8c605d4405cc918aec
Author: Francis Laniel <flaniel@xxxxxxxxxxxxxxxxxxx>
Date:   Wed Jun 8 17:24:46 2022 +0100

    arm64: Do not forget syscall when starting a new thread.
    
    [ 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@xxxxxxxxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20220608162447.666494-2-flaniel@xxxxxxxxxxxxxxxxxxx
    Signed-off-by: Will Deacon <will@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

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;
 }