From: Bodo Stroesser <[email protected]>
This patch implements the new ptrace option PTRACE_SYSEMU_SINGLESTEP, which
can be used by UML to singlestep a process: it will receive SINGLESTEP
interceptions for normal instructions and syscalls, but syscall execution will
be skipped just like with PTRACE_SYSEMU.
Signed-off-by: Bodo Stroesser <[email protected]>
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <[email protected]>
---
linux-2.6.git-paolo/arch/i386/kernel/ptrace.c | 21 +++++++++++++++++----
linux-2.6.git-paolo/include/linux/ptrace.h | 1 +
2 files changed, 18 insertions(+), 4 deletions(-)
diff -puN arch/i386/kernel/ptrace.c~sysemu-add-SYSEMU_SINGLESTEP arch/i386/kernel/ptrace.c
--- linux-2.6.git/arch/i386/kernel/ptrace.c~sysemu-add-SYSEMU_SINGLESTEP 2005-07-26 20:27:45.000000000 +0200
+++ linux-2.6.git-paolo/arch/i386/kernel/ptrace.c 2005-07-26 20:39:55.000000000 +0200
@@ -547,11 +547,17 @@ asmlinkage int sys_ptrace(long request,
wake_up_process(child);
break;
+ case PTRACE_SYSEMU_SINGLESTEP: /* Same as SYSEMU, but singlestep if not syscall */
case PTRACE_SINGLESTEP: /* set the trap flag. */
ret = -EIO;
if (!valid_signal(data))
break;
- clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+
+ if (request == PTRACE_SYSEMU_SINGLESTEP)
+ set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+ else
+ clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
+
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
set_singlestep(child);
child->exit_code = data;
@@ -686,7 +692,10 @@ void send_sigtrap(struct task_struct *ts
__attribute__((regparm(3)))
int do_syscall_trace(struct pt_regs *regs, int entryexit)
{
- int is_sysemu, is_singlestep, ret = 0;
+ int is_sysemu = test_thread_flag(TIF_SYSCALL_EMU), ret = 0;
+ /* With TIF_SYSCALL_EMU set we want to ignore TIF_SINGLESTEP */
+ int is_singlestep = !is_sysemu && test_thread_flag(TIF_SINGLESTEP);
+
/* do the secure computing check first */
secure_computing(regs->orig_eax);
@@ -696,8 +705,11 @@ int do_syscall_trace(struct pt_regs *reg
if (!(current->ptrace & PT_PTRACED))
goto out;
- is_sysemu = test_thread_flag(TIF_SYSCALL_EMU);
- is_singlestep = test_thread_flag(TIF_SINGLESTEP);
+ /* If a process stops on the 1st tracepoint with SYSCALL_TRACE
+ * and then is resumed with SYSEMU_SINGLESTEP, it will come in
+ * here. We have to check this and return */
+ if (is_sysemu && entryexit)
+ return 0;
/* Fake a debug trap */
if (is_singlestep)
@@ -728,6 +740,7 @@ int do_syscall_trace(struct pt_regs *reg
if (ret == 0)
return 0;
+ regs->orig_eax = -1; /* force skip of syscall restarting */
if (unlikely(current->audit_context))
audit_syscall_exit(current, AUDITSC_RESULT(regs->eax), regs->eax);
return 1;
diff -puN include/linux/ptrace.h~sysemu-add-SYSEMU_SINGLESTEP include/linux/ptrace.h
--- linux-2.6.git/include/linux/ptrace.h~sysemu-add-SYSEMU_SINGLESTEP 2005-07-26 20:27:45.000000000 +0200
+++ linux-2.6.git-paolo/include/linux/ptrace.h 2005-07-26 20:27:45.000000000 +0200
@@ -21,6 +21,7 @@
#define PTRACE_SYSCALL 24
#define PTRACE_SYSEMU 31
+#define PTRACE_SYSEMU_SINGLESTEP 32
/* 0x4200-0x4300 are reserved for architecture-independent additions. */
#define PTRACE_SETOPTIONS 0x4200
_
-
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