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signal: Simplify tracehook_report_syscall_exit

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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: 85ec7fd9f8 ("ptrace: introduce user_single_step_siginfo() helper")
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman
2018-04-16 14:18:26 -05:00
parent fb50f5a401
commit efc463adbc
6 changed files with 24 additions and 28 deletions
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17
include/linux/ptrace.h
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@@ -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