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SubjectRe: [RFC][PATCH] Demultiplexing SIGTRAP signal
Date
On Monday 22 September 2008 20:24:04 Ingo Molnar wrote:
> * Srinivasa Ds <srinivasa@in.ibm.com> wrote:
> > --- linux-2.6.27-rc7.orig/arch/ia64/include/asm/siginfo.h
> > +++ linux-2.6.27-rc7/arch/ia64/include/asm/siginfo.h
>
> please do not send patches that modify include/asm/ files, the
> include/asm-x86/ file should be modified instead.
>
> (this problem will go away in v2.6.28 when we'll move include/asm-x86/
> to arch/x86/include/)
>

Ingo, Sorry if I have confused you. Arch specific header files of ia64 and powerpc are
already moved to arch/ia64/include and arch/powerpc/include dirs.
So I have developed patch against these files. So Resending patch again.

Currently a SIGTRAP can denote any one of below reasons.
- Breakpoint hit
- H/W debug register hit
- Single step
- Signal sent through kill() or rasie()

Architectures like powerpc/parisc provides infrastructure to demultiplex
SIGTRAP signal by passing down the information for receiving SIGTRAP through
si_code of siginfot_t structure. Here is an attempt is generalise this
infrastructure by extending it to x86 and x86_64 archs.

Signed-off-by: Srinivasa DS <srinivasa@in.ibm.com>


---
arch/ia64/include/asm/siginfo.h | 5 -----
arch/powerpc/include/asm/siginfo.h | 5 -----
arch/x86/kernel/ptrace.c | 7 ++++---
arch/x86/kernel/traps_32.c | 4 +++-
arch/x86/kernel/traps_64.c | 2 +-
include/asm-generic/siginfo.h | 2 ++
include/asm-parisc/siginfo.h | 5 -----
include/asm-x86/ptrace.h | 2 +-
include/asm-x86/traps.h | 10 ++++++++++
9 files changed, 21 insertions(+), 21 deletions(-)
Index: linux-2.6.27-rc7/arch/ia64/include/asm/siginfo.h
===================================================================
--- linux-2.6.27-rc7.orig/arch/ia64/include/asm/siginfo.h
+++ linux-2.6.27-rc7/arch/ia64/include/asm/siginfo.h
@@ -113,11 +113,6 @@ typedef struct siginfo {
#undef NSIGSEGV
#define NSIGSEGV 3

-/*
- * SIGTRAP si_codes
- */
-#define TRAP_BRANCH (__SI_FAULT|3) /* process taken branch trap */
-#define TRAP_HWBKPT (__SI_FAULT|4) /* hardware breakpoint or watchpoint */
#undef NSIGTRAP
#define NSIGTRAP 4

Index: linux-2.6.27-rc7/arch/powerpc/include/asm/siginfo.h
===================================================================
--- linux-2.6.27-rc7.orig/arch/powerpc/include/asm/siginfo.h
+++ linux-2.6.27-rc7/arch/powerpc/include/asm/siginfo.h
@@ -15,11 +15,6 @@

#include <asm-generic/siginfo.h>

-/*
- * SIGTRAP si_codes
- */
-#define TRAP_BRANCH (__SI_FAULT|3) /* process taken branch trap */
-#define TRAP_HWBKPT (__SI_FAULT|4) /* hardware breakpoint or watchpoint */
#undef NSIGTRAP
#define NSIGTRAP 4

Index: linux-2.6.27-rc7/arch/x86/kernel/traps_32.c
===================================================================
--- linux-2.6.27-rc7.orig/arch/x86/kernel/traps_32.c
+++ linux-2.6.27-rc7/arch/x86/kernel/traps_32.c
@@ -891,6 +891,7 @@ void __kprobes do_debug(struct pt_regs *
{
struct task_struct *tsk = current;
unsigned int condition;
+ int si_code;

trace_hardirqs_fixup();

@@ -935,8 +936,9 @@ void __kprobes do_debug(struct pt_regs *
goto clear_TF_reenable;
}

+ si_code = get_si_code((unsigned long)condition);
/* Ok, finally something we can handle */
- send_sigtrap(tsk, regs, error_code);
+ send_sigtrap(tsk, regs, error_code, si_code);

/*
* Disable additional traps. They'll be re-enabled when
Index: linux-2.6.27-rc7/arch/x86/kernel/traps_64.c
===================================================================
--- linux-2.6.27-rc7.orig/arch/x86/kernel/traps_64.c
+++ linux-2.6.27-rc7/arch/x86/kernel/traps_64.c
@@ -936,7 +936,7 @@ asmlinkage void __kprobes do_debug(struc
tsk->thread.error_code = error_code;
info.si_signo = SIGTRAP;
info.si_errno = 0;
- info.si_code = TRAP_BRKPT;
+ info.si_code = get_si_code(condition);
info.si_addr = user_mode(regs) ? (void __user *)regs->ip : NULL;
force_sig_info(SIGTRAP, &info, tsk);

Index: linux-2.6.27-rc7/include/asm-generic/siginfo.h
===================================================================
--- linux-2.6.27-rc7.orig/include/asm-generic/siginfo.h
+++ linux-2.6.27-rc7/include/asm-generic/siginfo.h
@@ -199,6 +199,8 @@ typedef struct siginfo {
*/
#define TRAP_BRKPT (__SI_FAULT|1) /* process breakpoint */
#define TRAP_TRACE (__SI_FAULT|2) /* process trace trap */
+#define TRAP_BRANCH (__SI_FAULT|3) /* process taken branch trap */
+#define TRAP_HWBKPT (__SI_FAULT|4) /* hardware breakpoint/watchpoint */
#define NSIGTRAP 2

/*
Index: linux-2.6.27-rc7/include/asm-parisc/siginfo.h
===================================================================
--- linux-2.6.27-rc7.orig/include/asm-parisc/siginfo.h
+++ linux-2.6.27-rc7/include/asm-parisc/siginfo.h
@@ -3,11 +3,6 @@

#include <asm-generic/siginfo.h>

-/*
- * SIGTRAP si_codes
- */
-#define TRAP_BRANCH (__SI_FAULT|3) /* process taken branch trap */
-#define TRAP_HWBKPT (__SI_FAULT|4) /* hardware breakpoint or watchpoint */
#undef NSIGTRAP
#define NSIGTRAP 4

Index: linux-2.6.27-rc7/arch/x86/kernel/ptrace.c
===================================================================
--- linux-2.6.27-rc7.orig/arch/x86/kernel/ptrace.c
+++ linux-2.6.27-rc7/arch/x86/kernel/ptrace.c
@@ -1357,7 +1357,8 @@ const struct user_regset_view *task_user
#endif
}

-void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs, int error_code)
+void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs,
+ int error_code, int si_code)
{
struct siginfo info;

@@ -1366,7 +1367,7 @@ void send_sigtrap(struct task_struct *ts

memset(&info, 0, sizeof(info));
info.si_signo = SIGTRAP;
- info.si_code = TRAP_BRKPT;
+ info.si_code = si_code;

/* User-mode ip? */
info.si_addr = user_mode_vm(regs) ? (void __user *) regs->ip : NULL;
@@ -1476,5 +1477,5 @@ asmregparm void syscall_trace_leave(stru
*/
if (test_thread_flag(TIF_SINGLESTEP) &&
(current->ptrace & PT_PTRACED))
- send_sigtrap(current, regs, 0);
+ send_sigtrap(current, regs, 0, TRAP_BRKPT);
}
Index: linux-2.6.27-rc7/include/asm-x86/traps.h
===================================================================
--- linux-2.6.27-rc7.orig/include/asm-x86/traps.h
+++ linux-2.6.27-rc7/include/asm-x86/traps.h
@@ -36,6 +36,16 @@ void do_invalid_op(struct pt_regs *, lon
void do_general_protection(struct pt_regs *, long);
void do_nmi(struct pt_regs *, long);

+static inline int get_si_code(unsigned long condition)
+{
+ if (condition & DR_STEP)
+ return TRAP_TRACE;
+ else if (condition & (DR_TRAP0|DR_TRAP1|DR_TRAP2|DR_TRAP3))
+ return TRAP_HWBKPT;
+ else
+ return TRAP_BRKPT;
+}
+
extern int panic_on_unrecovered_nmi;
extern int kstack_depth_to_print;

Index: linux-2.6.27-rc7/include/asm-x86/ptrace.h
===================================================================
--- linux-2.6.27-rc7.orig/include/asm-x86/ptrace.h
+++ linux-2.6.27-rc7/include/asm-x86/ptrace.h
@@ -143,7 +143,7 @@ convert_ip_to_linear(struct task_struct

#ifdef CONFIG_X86_32
extern void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs,
- int error_code);
+ int error_code, int si_code);
#else
void signal_fault(struct pt_regs *regs, void __user *frame, char *where);
#endif

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