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Diffstat (limited to 'arch/i386/kernel/ptrace.c')
-rw-r--r--arch/i386/kernel/ptrace.c57
1 files changed, 39 insertions, 18 deletions
diff --git a/arch/i386/kernel/ptrace.c b/arch/i386/kernel/ptrace.c
index 5ee9e1d60653..5b569dc1c227 100644
--- a/arch/i386/kernel/ptrace.c
+++ b/arch/i386/kernel/ptrace.c
@@ -509,15 +509,27 @@ asmlinkage int sys_ptrace(long request, long pid, long addr, long data)
}
break;
+ case PTRACE_SYSEMU: /* continue and stop at next syscall, which will not be executed */
case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
case PTRACE_CONT: /* restart after signal. */
ret = -EIO;
if (!valid_signal(data))
break;
+ /* If we came here with PTRACE_SYSEMU and now continue with
+ * PTRACE_SYSCALL, entry.S used to intercept the syscall return.
+ * But it shouldn't!
+ * So we don't clear TIF_SYSCALL_EMU, which is always unused in
+ * this special case, to remember, we came from SYSEMU. That
+ * flag will be cleared by do_syscall_trace().
+ */
+ if (request == PTRACE_SYSEMU) {
+ set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+ } else if (request == PTRACE_CONT) {
+ clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+ }
if (request == PTRACE_SYSCALL) {
set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
- }
- else {
+ } else {
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
}
child->exit_code = data;
@@ -546,6 +558,8 @@ asmlinkage int sys_ptrace(long request, long pid, long addr, long data)
ret = -EIO;
if (!valid_signal(data))
break;
+ /*See do_syscall_trace to know why we don't clear
+ * TIF_SYSCALL_EMU.*/
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
set_singlestep(child);
child->exit_code = data;
@@ -678,37 +692,43 @@ void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs, int error_code)
* - triggered by current->work.syscall_trace
*/
__attribute__((regparm(3)))
-void do_syscall_trace(struct pt_regs *regs, int entryexit)
+int do_syscall_trace(struct pt_regs *regs, int entryexit)
{
+ int is_sysemu, is_systrace, is_singlestep, ret = 0;
/* do the secure computing check first */
secure_computing(regs->orig_eax);
- if (unlikely(current->audit_context)) {
- if (entryexit)
- audit_syscall_exit(current, AUDITSC_RESULT(regs->eax), regs->eax);
-
- /* Debug traps, when using PTRACE_SINGLESTEP, must be sent only
- * on the syscall exit path. Normally, when TIF_SYSCALL_AUDIT is
- * not used, entry.S will call us only on syscall exit, not
- * entry ; so when TIF_SYSCALL_AUDIT is used we must avoid
- * calling send_sigtrap() on syscall entry.
- */
- else if (is_singlestep)
- goto out;
- }
+ if (unlikely(current->audit_context) && entryexit)
+ audit_syscall_exit(current, AUDITSC_RESULT(regs->eax), regs->eax);
if (!(current->ptrace & PT_PTRACED))
goto out;
+ is_sysemu = test_thread_flag(TIF_SYSCALL_EMU);
+ is_systrace = test_thread_flag(TIF_SYSCALL_TRACE);
+ is_singlestep = test_thread_flag(TIF_SINGLESTEP);
+
+ /* We can detect the case of coming from PTRACE_SYSEMU and now running
+ * with PTRACE_SYSCALL or PTRACE_SINGLESTEP, by TIF_SYSCALL_EMU being
+ * set additionally.
+ * If so let's reset the flag and return without action (no singlestep
+ * nor syscall tracing, since no actual step has been executed).
+ */
+ if (is_sysemu && (is_systrace || is_singlestep)) {
+ clear_thread_flag(TIF_SYSCALL_EMU);
+ goto out;
+ }
+
/* Fake a debug trap */
if (test_thread_flag(TIF_SINGLESTEP))
send_sigtrap(current, regs, 0);
- if (!test_thread_flag(TIF_SYSCALL_TRACE))
+ if (!is_systrace && !is_sysemu)
goto out;
/* the 0x80 provides a way for the tracing parent to distinguish
between a syscall stop and SIGTRAP delivery */
+ /* Note that the debugger could change the result of test_thread_flag!*/
ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) ? 0x80 : 0));
/*
@@ -720,9 +740,10 @@ void do_syscall_trace(struct pt_regs *regs, int entryexit)
send_sig(current->exit_code, current, 1);
current->exit_code = 0;
}
+ ret = is_sysemu;
out:
if (unlikely(current->audit_context) && !entryexit)
audit_syscall_entry(current, AUDIT_ARCH_I386, regs->orig_eax,
regs->ebx, regs->ecx, regs->edx, regs->esi);
-
+ return ret;
}