Commit efc463ad authored by Eric W. Biederman's avatar Eric W. Biederman
Browse files

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: 85ec7fd9 ("ptrace: introduce user_single_step_siginfo() helper")
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
parent fb50f5a4

arch/powerpc/include/asm/ptrace.h

+1 −1
Original line number Diff line number Diff line
@@ -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

arch/powerpc/kernel/traps.c

+2 −5
Original line number Diff line number Diff line
@@ -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,

arch/x86/include/asm/ptrace.h

+1 −1
Original line number Diff line number Diff line
@@ -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

arch/x86/kernel/ptrace.c

+5 −6
Original line number Diff line number Diff line
@@ -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);

}

include/linux/ptrace.h

+11 −6
Original line number Diff line number Diff line
@@ -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