[PATCH 4/6] ptrace_get_syscall_info: factor out ptrace_get_syscall_info_op

Dmitry V. Levin
2025-01-07T23:04:48Z

Move the code that calculates the type of the system call stop
out of ptrace_get_syscall_info() into a separate function
ptrace_get_syscall_info_op() which is going to be used later
to implement PTRACE_SET_SYSCALL_INFO API.

Signed-off-by: Dmitry V. Levin <ldv@strace.io>
---
kernel/ptrace.c | 52 ++++++++++++++++++++++++++++++-------------------
1 file changed, 32 insertions(+), 20 deletions(-)

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index d5f89f9ef29f..e7e0003cc8e0 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -965,19 +965,8 @@ ptrace_get_syscall_info_exit(struct task_struct *child, struct pt_regs *regs,
}

static int
-ptrace_get_syscall_info(struct task_struct *child, unsigned long user_size,
- void __user *datavp)
+ptrace_get_syscall_info_op(struct task_struct *child)
{
- struct pt_regs *regs = task_pt_regs(child);
- struct ptrace_syscall_info info = {
- .op = PTRACE_SYSCALL_INFO_NONE,
- .arch = syscall_get_arch(child),
- .instruction_pointer = instruction_pointer(regs),
- .stack_pointer = user_stack_pointer(regs),
- };
- unsigned long actual_size = offsetof(struct ptrace_syscall_info, entry);
- unsigned long write_size;
-
/*
* This does not need lock_task_sighand() to access
* child->last_siginfo because ptrace_freeze_traced()
@@ -988,18 +977,41 @@ ptrace_get_syscall_info(struct task_struct *child, unsigned long user_size,
case SIGTRAP | 0x80:
switch (child->ptrace_message) {
case PTRACE_EVENTMSG_SYSCALL_ENTRY:
- actual_size = ptrace_get_syscall_info_entry(child, regs,
- &info);
- break;
+ return PTRACE_SYSCALL_INFO_ENTRY;
case PTRACE_EVENTMSG_SYSCALL_EXIT:
- actual_size = ptrace_get_syscall_info_exit(child, regs,
- &info);
- break;
+ return PTRACE_SYSCALL_INFO_EXIT;
}
break;
case SIGTRAP | (PTRACE_EVENT_SECCOMP << 8):
- actual_size = ptrace_get_syscall_info_seccomp(child, regs,
- &info);
+ return PTRACE_SYSCALL_INFO_SECCOMP;
+ }
+
+ return PTRACE_SYSCALL_INFO_NONE;
+}
+
+static int
+ptrace_get_syscall_info(struct task_struct *child, unsigned long user_size,
+ void __user *datavp)
+{
+ struct pt_regs *regs = task_pt_regs(child);
+ struct ptrace_syscall_info info = {
+ .op = ptrace_get_syscall_info_op(child),
+ .arch = syscall_get_arch(child),
+ .instruction_pointer = instruction_pointer(regs),
+ .stack_pointer = user_stack_pointer(regs),
+ };
+ unsigned long actual_size = offsetof(struct ptrace_syscall_info, entry);
+ unsigned long write_size;
+
+ switch (info.op) {
+ case PTRACE_SYSCALL_INFO_ENTRY:
+ actual_size = ptrace_get_syscall_info_entry(child, regs, &info);
+ break;
+ case PTRACE_SYSCALL_INFO_EXIT:
+ actual_size = ptrace_get_syscall_info_exit(child, regs, &info);
+ break;
+ case PTRACE_SYSCALL_INFO_SECCOMP:
+ actual_size = ptrace_get_syscall_info_seccomp(child, regs, &info);
break;
}

--
ldv