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Message-Id: <20180918000546.12552-1-ebiederm@xmission.com>
Date: Tue, 18 Sep 2018 02:05:27 +0200
From: "Eric W. Biederman" <ebiederm@...ssion.com>
To: linux-kernel@...r.kernel.org
Cc: linux-arch@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: [REVIEW][PATCH 01/20] signal: Simplify tracehook_report_syscall_exit
Replace user_single_step_siginfo with user_single_step_report
that allocates siginfo structure on the stack and sends it.
This allows tracehook_report_syscall_exit to become a simple
if statement that calls user_single_step_report or ptrace_report_syscall
depending on the value of step.
Update the default helper function now called user_single_step_report
to explicitly set si_code to SI_USER and to set si_uid and si_pid to 0.
The default helper has always been doing this (using memset) but it
was far from obvious.
The powerpc helper can now just call force_sig_fault.
The x86 helper can now just call send_sigtrap.
Unfortunately the default implementation of user_single_step_report
can not use force_sig_fault as it does not use a SIGTRAP si_code.
So it has to carefully setup the siginfo and use use force_sig_info.
The net result is code that is easier to understand and simpler
to maintain.
Ref: 85ec7fd9f8e5 ("ptrace: introduce user_single_step_siginfo() helper")
Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
---
arch/powerpc/include/asm/ptrace.h | 2 +-
arch/powerpc/kernel/traps.c | 7 ++-----
arch/x86/include/asm/ptrace.h | 2 +-
arch/x86/kernel/ptrace.c | 11 +++++------
include/linux/ptrace.h | 17 +++++++++++------
include/linux/tracehook.h | 13 ++++---------
6 files changed, 24 insertions(+), 28 deletions(-)
diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
index 447cbd1bee99..5b480e1d5909 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -149,7 +149,7 @@ do { \
#define arch_has_single_step() (1)
#define arch_has_block_step() (!cpu_has_feature(CPU_FTR_601))
-#define ARCH_HAS_USER_SINGLE_STEP_INFO
+#define ARCH_HAS_USER_SINGLE_STEP_REPORT
/*
* kprobe-based event tracer support
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index c85adb858271..f651fa91cdc9 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -307,12 +307,9 @@ void die(const char *str, struct pt_regs *regs, long err)
}
NOKPROBE_SYMBOL(die);
-void user_single_step_siginfo(struct task_struct *tsk,
- struct pt_regs *regs, siginfo_t *info)
+void user_single_step_report(struct pt_regs *regs)
{
- info->si_signo = SIGTRAP;
- info->si_code = TRAP_TRACE;
- info->si_addr = (void __user *)regs->nip;
+ force_sig_fault(SIGTRAP, TRAP_TRACE, (void __user *)regs->nip, current);
}
static void show_signal_msg(int signr, struct pt_regs *regs, int code,
diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index 6de1fd3d0097..e353f08b7fe2 100644
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -263,7 +263,7 @@ static inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
#define arch_has_block_step() (boot_cpu_data.x86 >= 6)
#endif
-#define ARCH_HAS_USER_SINGLE_STEP_INFO
+#define ARCH_HAS_USER_SINGLE_STEP_REPORT
/*
* When hitting ptrace_stop(), we cannot return using SYSRET because
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index e2ee403865eb..94bd6e89129a 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -1382,12 +1382,6 @@ static void fill_sigtrap_info(struct task_struct *tsk,
info->si_addr = user_mode(regs) ? (void __user *)regs->ip : NULL;
}
-void user_single_step_siginfo(struct task_struct *tsk,
- struct pt_regs *regs,
- struct siginfo *info)
-{
- fill_sigtrap_info(tsk, regs, 0, TRAP_BRKPT, info);
-}
void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs,
int error_code, int si_code)
@@ -1399,3 +1393,8 @@ void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs,
/* Send us the fake SIGTRAP */
force_sig_info(SIGTRAP, &info, tsk);
}
+
+void user_single_step_report(struct pt_regs *regs)
+{
+ send_sigtrap(current, regs, 0, TRAP_BRKPT);
+}
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index 4f36431c380b..1de2235511c8 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -336,14 +336,19 @@ static inline void user_enable_block_step(struct task_struct *task)
extern void user_enable_block_step(struct task_struct *);
#endif /* arch_has_block_step */
-#ifdef ARCH_HAS_USER_SINGLE_STEP_INFO
-extern void user_single_step_siginfo(struct task_struct *tsk,
- struct pt_regs *regs, siginfo_t *info);
+#ifdef ARCH_HAS_USER_SINGLE_STEP_REPORT
+extern void user_single_step_report(struct pt_regs *regs);
#else
-static inline void user_single_step_siginfo(struct task_struct *tsk,
- struct pt_regs *regs, siginfo_t *info)
+static inline void user_single_step_report(struct pt_regs *regs)
{
- info->si_signo = SIGTRAP;
+ siginfo_t info;
+ clear_siginfo(&info);
+ info.si_signo = SIGTRAP;
+ info.si_errno = 0;
+ info.si_code = SI_USER;
+ info.si_pid = 0;
+ info.si_uid = 0;
+ force_sig_info(info.si_signo, &info, current);
}
#endif
diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h
index 05589a3e37f4..40b0b4c1bf7b 100644
--- a/include/linux/tracehook.h
+++ b/include/linux/tracehook.h
@@ -123,15 +123,10 @@ static inline __must_check int tracehook_report_syscall_entry(
*/
static inline void tracehook_report_syscall_exit(struct pt_regs *regs, int step)
{
- if (step) {
- siginfo_t info;
- clear_siginfo(&info);
- user_single_step_siginfo(current, regs, &info);
- force_sig_info(SIGTRAP, &info, current);
- return;
- }
-
- ptrace_report_syscall(regs);
+ if (step)
+ user_single_step_report(regs);
+ else
+ ptrace_report_syscall(regs);
}
/**
--
2.17.1
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