[PATCH 1/4] arm64: expose orig_x0 in the user_pt_regs structure

[Andrei Vagin]

orig_x0 is recorded at the start of the syscall entry and then it is
used for resetting the argument back to its original value during
syscall restarts.

If orig_x0 isn't available from user-space, this makes it tricky to
manage arguments of restarted system calls.

Cc: Keno Fischer <k...@juliacomputing.com>
Signed-off-by: Andrei Vagin <ava...@gmail.com>
---
 arch/arm64/include/asm/ptrace.h      | 2 +-
 arch/arm64/include/uapi/asm/ptrace.h | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
index e58bca832dff..d4cdf98ac003 100644
--- a/arch/arm64/include/asm/ptrace.h
+++ b/arch/arm64/include/asm/ptrace.h
@@ -183,9 +183,9 @@ struct pt_regs {
                        u64 sp;
                        u64 pc;
                        u64 pstate;
+                       u64 orig_x0;
                };
        };
-       u64 orig_x0;
 #ifdef __AARCH64EB__
        u32 unused2;
        s32 syscallno;
diff --git a/arch/arm64/include/uapi/asm/ptrace.h 
b/arch/arm64/include/uapi/asm/ptrace.h
index 758ae984ff97..3c118c5b0893 100644
--- a/arch/arm64/include/uapi/asm/ptrace.h
+++ b/arch/arm64/include/uapi/asm/ptrace.h
@@ -90,6 +90,7 @@ struct user_pt_regs {
        __u64           sp;
        __u64           pc;
        __u64           pstate;
+       __u64           orig_x0;
 };
 
 struct user_fpsimd_state {
-- 
2.29.2