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tracehook: syscall

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This adds standard tracehook.h inlines for arch code to call when
TIF_SYSCALL_TRACE has been set.  This replaces having each arch implement
the ptrace guts for its syscall tracing support.

Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Reviewed-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Roland McGrath 2008-07-25 19:45:52 -07:00 committed by Linus Torvalds
parent 445a91d2fe
commit 283d7559e7
1 changed files with 70 additions and 0 deletions
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70
include/linux/tracehook.h
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@ -66,6 +66,76 @@ static inline int tracehook_expect_breakpoints(struct task_struct *task)
return (task_ptrace(task) & PT_PTRACED) != 0; return (task_ptrace(task) & PT_PTRACED) != 0;
} }
/*
* ptrace report for syscall entry and exit looks identical.
*/
static inline void ptrace_report_syscall(struct pt_regs *regs)
{
int ptrace = task_ptrace(current);
if (!(ptrace & PT_PTRACED))
return;
ptrace_notify(SIGTRAP | ((ptrace & PT_TRACESYSGOOD) ? 0x80 : 0));
/*
* this isn't the same as continuing with a signal, but it will do
* for normal use. strace only continues with a signal if the
* stopping signal is not SIGTRAP. -brl
*/
if (current->exit_code) {
send_sig(current->exit_code, current, 1);
current->exit_code = 0;
}
}
/**
* tracehook_report_syscall_entry - task is about to attempt a system call
* @regs: user register state of current task
*
* This will be called if %TIF_SYSCALL_TRACE has been set, when the
* current task has just entered the kernel for a system call.
* Full user register state is available here. Changing the values
* in @regs can affect the system call number and arguments to be tried.
* It is safe to block here, preventing the system call from beginning.
*
* Returns zero normally, or nonzero if the calling arch code should abort
* the system call. That must prevent normal entry so no system call is
* made. If @task ever returns to user mode after this, its register state
* is unspecified, but should be something harmless like an %ENOSYS error
* return.
*
* Called without locks, just after entering kernel mode.
*/
static inline __must_check int tracehook_report_syscall_entry(
struct pt_regs *regs)
{
ptrace_report_syscall(regs);
return 0;
}
/**
* tracehook_report_syscall_exit - task has just finished a system call
* @regs: user register state of current task
* @step: nonzero if simulating single-step or block-step
*
* This will be called if %TIF_SYSCALL_TRACE has been set, when the
* current task has just finished an attempted system call. Full
* user register state is available here. It is safe to block here,
* preventing signals from being processed.
*
* If @step is nonzero, this report is also in lieu of the normal
* trap that would follow the system call instruction because
* user_enable_block_step() or user_enable_single_step() was used.
* In this case, %TIF_SYSCALL_TRACE might not be set.
*
* Called without locks, just before checking for pending signals.
*/
static inline void tracehook_report_syscall_exit(struct pt_regs *regs, int step)
{
ptrace_report_syscall(regs);
}
/** /**
* tracehook_unsafe_exec - check for exec declared unsafe due to tracing * tracehook_unsafe_exec - check for exec declared unsafe due to tracing
* @task: current task doing exec * @task: current task doing exec