[PATCH] Uml support: reorganize PTRACE_SYSEMU support
With this patch, we change the way we handle switching from PTRACE_SYSEMU to
PTRACE_{SINGLESTEP,SYSCALL}, to free TIF_SYSCALL_EMU from double use as a
preparation for PTRACE_SYSEMU_SINGLESTEP extension, without changing the
behavior of the host kernel.
Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S
index b389e5f..9a47723 100644
--- a/arch/i386/kernel/entry.S
+++ b/arch/i386/kernel/entry.S
@@ -339,12 +339,18 @@
xorl %edx,%edx
call do_syscall_trace
cmpl $0, %eax
- jne syscall_exit # ret != 0 -> running under PTRACE_SYSEMU,
+ jne syscall_skip # ret != 0 -> running under PTRACE_SYSEMU,
# so must skip actual syscall
movl ORIG_EAX(%esp), %eax
cmpl $(nr_syscalls), %eax
jnae syscall_call
jmp syscall_exit
+syscall_skip:
+ cli # make sure we don't miss an interrupt
+ # setting need_resched or sigpending
+ # between sampling and the iret
+ movl TI_flags(%ebp), %ecx
+ jmp work_pending
# perform syscall exit tracing
ALIGN
diff --git a/arch/i386/kernel/ptrace.c b/arch/i386/kernel/ptrace.c
index 5b569dc..18642f0 100644
--- a/arch/i386/kernel/ptrace.c
+++ b/arch/i386/kernel/ptrace.c
@@ -515,21 +515,14 @@
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) {
+ clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+ } else if (request == PTRACE_SYSCALL) {
set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+ clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
} else {
+ clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
}
child->exit_code = data;
@@ -558,8 +551,7 @@
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_EMU);
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
set_singlestep(child);
child->exit_code = data;
@@ -694,7 +686,7 @@
__attribute__((regparm(3)))
int do_syscall_trace(struct pt_regs *regs, int entryexit)
{
- int is_sysemu, is_systrace, is_singlestep, ret = 0;
+ int is_sysemu, is_singlestep, ret = 0;
/* do the secure computing check first */
secure_computing(regs->orig_eax);
@@ -705,25 +697,13 @@
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))
+ if (is_singlestep)
send_sigtrap(current, regs, 0);
- if (!is_systrace && !is_sysemu)
+ if (!test_thread_flag(TIF_SYSCALL_TRACE) && !is_sysemu)
goto out;
/* the 0x80 provides a way for the tracing parent to distinguish
@@ -745,5 +725,10 @@
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;
+ if (ret == 0)
+ return 0;
+
+ if (unlikely(current->audit_context))
+ audit_syscall_exit(current, AUDITSC_RESULT(regs->eax), regs->eax);
+ return 1;
}