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

Andrei Vagin
2021-03-22T22:54:02Z

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 <keno@juliacomputing.com>
Signed-off-by: Andrei Vagin <avagin@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