From: "bibo,mao" <[EMAIL PROTECTED]>
http://www.gelato.org/community/view_linear.php?id=1_1036&from=authors&value=Ian%20Wienand#1_1039,
if single step on break instruction, the break fault has higher priority
than the single-step trap. When the break fault handler is entered, it
advances the IP by 1 instruction so break instruction single-stepping is
skipped, actually it is next instruction which is single stepped.
This patch modifies this, it adds TIF_SINGLESTEP bit for thread flags, and
generate a fake sigtrap when single stepping break instruction. Test case
in attachment can verify this. Any comments is welcome.
Signed-off-by: bibo, mao <[EMAIL PROTECTED]>
Cc: "Luck, Tony" <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
---
arch/ia64/kernel/ptrace.c | 12 ++++++------
include/asm-ia64/thread_info.h | 4 +++-
2 files changed, 9 insertions(+), 7 deletions(-)
diff -puN arch/ia64/kernel/ptrace.c~ia64-enable-singlestep-on-system-call
arch/ia64/kernel/ptrace.c
--- a/arch/ia64/kernel/ptrace.c~ia64-enable-singlestep-on-system-call
+++ a/arch/ia64/kernel/ptrace.c
@@ -1405,6 +1405,7 @@ ptrace_disable (struct task_struct *chil
struct ia64_psr *child_psr = ia64_psr(task_pt_regs(child));
/* make sure the single step/taken-branch trap bits are not set: */
+ clear_tsk_thread_flag(child, TIF_SINGLESTEP);
child_psr->ss = 0;
child_psr->tb = 0;
}
@@ -1525,6 +1526,7 @@ sys_ptrace (long request, pid_t pid, uns
* Make sure the single step/taken-branch trap bits
* are not set:
*/
+ clear_tsk_thread_flag(child, TIF_SINGLESTEP);
ia64_psr(pt)->ss = 0;
ia64_psr(pt)->tb = 0;
@@ -1556,6 +1558,7 @@ sys_ptrace (long request, pid_t pid, uns
goto out_tsk;
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+ set_tsk_thread_flag(child, TIF_SINGLESTEP);
if (request == PTRACE_SINGLESTEP) {
ia64_psr(pt)->ss = 1;
} else {
@@ -1595,13 +1598,9 @@ sys_ptrace (long request, pid_t pid, uns
}
-void
+static void
syscall_trace (void)
{
- if (!test_thread_flag(TIF_SYSCALL_TRACE))
- return;
- if (!(current->ptrace & PT_PTRACED))
- return;
/*
* The 0x80 provides a way for the tracing parent to
* distinguish between a syscall stop and SIGTRAP delivery.
@@ -1664,7 +1663,8 @@ syscall_trace_leave (long arg0, long arg
audit_syscall_exit(success, result);
}
- if (test_thread_flag(TIF_SYSCALL_TRACE)
+ if ((test_thread_flag(TIF_SYSCALL_TRACE)
+ || test_thread_flag(TIF_SINGLESTEP))
&& (current->ptrace & PT_PTRACED))
syscall_trace();
}
diff -puN include/asm-ia64/thread_info.h~ia64-enable-singlestep-on-system-call
include/asm-ia64/thread_info.h
--- a/include/asm-ia64/thread_info.h~ia64-enable-singlestep-on-system-call
+++ a/include/asm-ia64/thread_info.h
@@ -84,6 +84,7 @@ struct thread_info {
#define TIF_NEED_RESCHED 2 /* rescheduling necessary */
#define TIF_SYSCALL_TRACE 3 /* syscall trace active */
#define TIF_SYSCALL_AUDIT 4 /* syscall auditing active */
+#define TIF_SINGLESTEP 5 /* restore singlestep on return to user
mode */
#define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling
TIF_NEED_RESCHED */
#define TIF_MEMDIE 17
#define TIF_MCA_INIT 18 /* this task is processing MCA or INIT
*/
@@ -92,7 +93,8 @@ struct thread_info {
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
-#define _TIF_SYSCALL_TRACEAUDIT (_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT)
+#define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
+#define _TIF_SYSCALL_TRACEAUDIT
(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP)
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
_
-
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