[PATCH 2/6] ptrace: Remove the unnecessary arguments from arch_ptrace_stop

From: Eric W. Biederman
Date: Fri Sep 24 2021 - 11:22:13 EST


Both arch_ptrace_stop_needed and arch_ptrace_stop are called with an
exit_code and a siginfo structure. Neither argument is used by any of
the implementations so just remove the unneeded arguments.

The two arechitectures that implement arch_ptrace_stop are ia64 and
sparc. Both architectures flush their register stacks before a
ptrace_stack so that all of the register information can be accessed
by debuggers.

As the question of if a register stack needs to be flushed is
independent of why ptrace is stopping not needing arguments make sense.

Cc: David Miller <davem@xxxxxxxxxxxxx>
Cc: sparclinux@xxxxxxxxxxxxxxx
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
---

Resent because my little one distracted me as I was sending this last
night and I did not manage to copy the sparc and ia64 folks.

arch/ia64/include/asm/ptrace.h | 4 ++--
arch/sparc/include/asm/ptrace.h | 8 ++++----
include/linux/ptrace.h | 22 +++++++++-------------
kernel/signal.c | 4 ++--
4 files changed, 17 insertions(+), 21 deletions(-)

diff --git a/arch/ia64/include/asm/ptrace.h b/arch/ia64/include/asm/ptrace.h
index 08179135905c..f15504f75f10 100644
--- a/arch/ia64/include/asm/ptrace.h
+++ b/arch/ia64/include/asm/ptrace.h
@@ -129,9 +129,9 @@ static inline long regs_return_value(struct pt_regs *regs)
extern void ia64_decrement_ip (struct pt_regs *pt);

extern void ia64_ptrace_stop(void);
- #define arch_ptrace_stop(code, info) \
+ #define arch_ptrace_stop() \
ia64_ptrace_stop()
- #define arch_ptrace_stop_needed(code, info) \
+ #define arch_ptrace_stop_needed() \
(!test_thread_flag(TIF_RESTORE_RSE))

extern void ptrace_attach_sync_user_rbs (struct task_struct *);
diff --git a/arch/sparc/include/asm/ptrace.h b/arch/sparc/include/asm/ptrace.h
index 71dd82b43cc5..d1419e669027 100644
--- a/arch/sparc/include/asm/ptrace.h
+++ b/arch/sparc/include/asm/ptrace.h
@@ -26,12 +26,12 @@ static inline bool pt_regs_clear_syscall(struct pt_regs *regs)
return (regs->tstate &= ~TSTATE_SYSCALL);
}

-#define arch_ptrace_stop_needed(exit_code, info) \
+#define arch_ptrace_stop_needed() \
({ flush_user_windows(); \
get_thread_wsaved() != 0; \
})

-#define arch_ptrace_stop(exit_code, info) \
+#define arch_ptrace_stop() \
synchronize_user_stack()

#define current_pt_regs() \
@@ -129,12 +129,12 @@ static inline bool pt_regs_clear_syscall(struct pt_regs *regs)
return (regs->psr &= ~PSR_SYSCALL);
}

-#define arch_ptrace_stop_needed(exit_code, info) \
+#define arch_ptrace_stop_needed() \
({ flush_user_windows(); \
current_thread_info()->w_saved != 0; \
})

-#define arch_ptrace_stop(exit_code, info) \
+#define arch_ptrace_stop() \
synchronize_user_stack()

#define current_pt_regs() \
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index b5ebf6c01292..8aee2945ff08 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -362,29 +362,25 @@ static inline void user_single_step_report(struct pt_regs *regs)
#ifndef arch_ptrace_stop_needed
/**
* arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
- * @code: current->exit_code value ptrace will stop with
- * @info: siginfo_t pointer (or %NULL) for signal ptrace will stop with
*
* This is called with the siglock held, to decide whether or not it's
- * necessary to release the siglock and call arch_ptrace_stop() with the
- * same @code and @info arguments. It can be defined to a constant if
- * arch_ptrace_stop() is never required, or always is. On machines where
- * this makes sense, it should be defined to a quick test to optimize out
- * calling arch_ptrace_stop() when it would be superfluous. For example,
- * if the thread has not been back to user mode since the last stop, the
- * thread state might indicate that nothing needs to be done.
+ * necessary to release the siglock and call arch_ptrace_stop(). It can be
+ * defined to a constant if arch_ptrace_stop() is never required, or always
+ * is. On machines where this makes sense, it should be defined to a quick
+ * test to optimize out calling arch_ptrace_stop() when it would be
+ * superfluous. For example, if the thread has not been back to user mode
+ * since the last stop, the thread state might indicate that nothing needs
+ * to be done.
*
* This is guaranteed to be invoked once before a task stops for ptrace and
* may include arch-specific operations necessary prior to a ptrace stop.
*/
-#define arch_ptrace_stop_needed(code, info) (0)
+#define arch_ptrace_stop_needed() (0)
#endif

#ifndef arch_ptrace_stop
/**
* arch_ptrace_stop - Do machine-specific work before stopping for ptrace
- * @code: current->exit_code value ptrace will stop with
- * @info: siginfo_t pointer (or %NULL) for signal ptrace will stop with
*
* This is called with no locks held when arch_ptrace_stop_needed() has
* just returned nonzero. It is allowed to block, e.g. for user memory
@@ -394,7 +390,7 @@ static inline void user_single_step_report(struct pt_regs *regs)
* we only do it when the arch requires it for this particular stop, as
* indicated by arch_ptrace_stop_needed().
*/
-#define arch_ptrace_stop(code, info) do { } while (0)
+#define arch_ptrace_stop() do { } while (0)
#endif

#ifndef current_pt_regs
diff --git a/kernel/signal.c b/kernel/signal.c
index 9f2dc9cf3208..c9759ff2cb43 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2200,7 +2200,7 @@ static void ptrace_stop(int exit_code, int why, int clear_code, kernel_siginfo_t
{
bool gstop_done = false;

- if (arch_ptrace_stop_needed(exit_code, info)) {
+ if (arch_ptrace_stop_needed()) {
/*
* The arch code has something special to do before a
* ptrace stop. This is allowed to block, e.g. for faults
@@ -2210,7 +2210,7 @@ static void ptrace_stop(int exit_code, int why, int clear_code, kernel_siginfo_t
* any signal bookkeeping like checking group_stop_count.
*/
spin_unlock_irq(&current->sighand->siglock);
- arch_ptrace_stop(exit_code, info);
+ arch_ptrace_stop();
spin_lock_irq(&current->sighand->siglock);
}

--
2.20.1