2020-07-19 02:20:34

by Max Filippov

[permalink] [raw]
Subject: [PATCH 1/3] xtensa: expose syscall through user_pt_regs

Use one of the reserved slots in struct user_pt_regs to return syscall
number in the GPR regset. Update syscall number from the GPR regset only
when it's non-zero.

Signed-off-by: Max Filippov <[email protected]>
---
arch/xtensa/include/uapi/asm/ptrace.h | 3 ++-
arch/xtensa/kernel/ptrace.c | 4 ++++
2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/xtensa/include/uapi/asm/ptrace.h b/arch/xtensa/include/uapi/asm/ptrace.h
index 2ec0f9100a06..50db3e0a6341 100644
--- a/arch/xtensa/include/uapi/asm/ptrace.h
+++ b/arch/xtensa/include/uapi/asm/ptrace.h
@@ -50,7 +50,8 @@ struct user_pt_regs {
__u32 windowstart;
__u32 windowbase;
__u32 threadptr;
- __u32 reserved[7 + 48];
+ __u32 syscall;
+ __u32 reserved[6 + 48];
__u32 a[64];
};

diff --git a/arch/xtensa/kernel/ptrace.c b/arch/xtensa/kernel/ptrace.c
index 0278d7dfb4d6..437b4297948d 100644
--- a/arch/xtensa/kernel/ptrace.c
+++ b/arch/xtensa/kernel/ptrace.c
@@ -52,6 +52,7 @@ static int gpr_get(struct task_struct *target,
.threadptr = regs->threadptr,
.windowbase = regs->windowbase,
.windowstart = regs->windowstart,
+ .syscall = regs->syscall,
};

memcpy(newregs.a,
@@ -91,6 +92,9 @@ static int gpr_set(struct task_struct *target,
regs->sar = newregs.sar;
regs->threadptr = newregs.threadptr;

+ if (newregs.syscall)
+ regs->syscall = newregs.syscall;
+
if (newregs.windowbase != regs->windowbase ||
newregs.windowstart != regs->windowstart) {
u32 rotws, wmask;
--
2.20.1