aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorJason Wessel <jason.wessel@windriver.com>2008-09-26 10:36:41 -0500
committerJason Wessel <jason.wessel@windriver.com>2008-09-26 10:36:41 -0500
commitd7161a65341556bacb5e6654e133803f46f51063 (patch)
treeb2933dc2ce1435956c193c37fd53a3d5530fe9d7
parent18d6522b86d21a04c8ac1ea79747e2e434a956d9 (diff)
kgdb, x86, arm, mips, powerpc: ignore user space single stepping
On the x86 arch, user space single step exceptions should be ignored if they occur in the kernel space, such as ptrace stepping through a system call. First check if it is kgdb that is executing a single step, then ensure it is not an accidental traversal into the user space, while in kgdb, any other time the TIF_SINGLESTEP is set, kgdb should ignore the exception. On x86, arm, mips and powerpc, the kgdb_contthread usage was inconsistent with the way single stepping is implemented in the kgdb core. The arch specific stub should always set the kgdb_cpu_doing_single_step correctly if it is single stepping. This allows kgdb to correctly process an instruction steps if ptrace happens to be requesting an instruction step over a system call. Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
-rw-r--r--arch/arm/kernel/kgdb.c2
-rw-r--r--arch/mips/kernel/kgdb.c3
-rw-r--r--arch/powerpc/kernel/kgdb.c5
-rw-r--r--arch/x86/kernel/kgdb.c18
-rw-r--r--kernel/kgdb.c8
5 files changed, 18 insertions, 18 deletions
diff --git a/arch/arm/kernel/kgdb.c b/arch/arm/kernel/kgdb.c
index aaffaecffcd..ba8ccfede96 100644
--- a/arch/arm/kernel/kgdb.c
+++ b/arch/arm/kernel/kgdb.c
@@ -111,8 +111,6 @@ int kgdb_arch_handle_exception(int exception_vector, int signo,
case 'D':
case 'k':
case 'c':
- kgdb_contthread = NULL;
-
/*
* Try to read optional parameter, pc unchanged if no parm.
* If this was a compiled breakpoint, we need to move
diff --git a/arch/mips/kernel/kgdb.c b/arch/mips/kernel/kgdb.c
index 8f6d58ede33..6e152c80cd4 100644
--- a/arch/mips/kernel/kgdb.c
+++ b/arch/mips/kernel/kgdb.c
@@ -236,8 +236,7 @@ int kgdb_arch_handle_exception(int vector, int signo, int err_code,
atomic_set(&kgdb_cpu_doing_single_step, -1);
if (remcom_in_buffer[0] == 's')
- if (kgdb_contthread)
- atomic_set(&kgdb_cpu_doing_single_step, cpu);
+ atomic_set(&kgdb_cpu_doing_single_step, cpu);
return 0;
}
diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c
index b4fdf2f2743..fe8f71dd0b3 100644
--- a/arch/powerpc/kernel/kgdb.c
+++ b/arch/powerpc/kernel/kgdb.c
@@ -347,9 +347,8 @@ int kgdb_arch_handle_exception(int vector, int signo, int err_code,
linux_regs->msr |= MSR_SE;
#endif
kgdb_single_step = 1;
- if (kgdb_contthread)
- atomic_set(&kgdb_cpu_doing_single_step,
- raw_smp_processor_id());
+ atomic_set(&kgdb_cpu_doing_single_step,
+ raw_smp_processor_id());
}
return 0;
}
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index f47f0eb886b..00f7896c9a1 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -378,10 +378,8 @@ int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
if (remcomInBuffer[0] == 's') {
linux_regs->flags |= X86_EFLAGS_TF;
kgdb_single_step = 1;
- if (kgdb_contthread) {
- atomic_set(&kgdb_cpu_doing_single_step,
- raw_smp_processor_id());
- }
+ atomic_set(&kgdb_cpu_doing_single_step,
+ raw_smp_processor_id());
}
get_debugreg(dr6, 6);
@@ -466,9 +464,15 @@ static int __kgdb_notify(struct die_args *args, unsigned long cmd)
case DIE_DEBUG:
if (atomic_read(&kgdb_cpu_doing_single_step) ==
- raw_smp_processor_id() &&
- user_mode(regs))
- return single_step_cont(regs, args);
+ raw_smp_processor_id()) {
+ if (user_mode(regs))
+ return single_step_cont(regs, args);
+ break;
+ } else if (test_thread_flag(TIF_SINGLESTEP))
+ /* This means a user thread is single stepping
+ * a system call which should be ignored
+ */
+ return NOTIFY_DONE;
/* fall through */
default:
if (user_mode(regs))
diff --git a/kernel/kgdb.c b/kernel/kgdb.c
index 949806ab67d..25d955dbb98 100644
--- a/kernel/kgdb.c
+++ b/kernel/kgdb.c
@@ -1462,7 +1462,7 @@ acquirelock:
* Get the passive CPU lock which will hold all the non-primary
* CPU in a spin state while the debugger is active
*/
- if (!kgdb_single_step || !kgdb_contthread) {
+ if (!kgdb_single_step) {
for (i = 0; i < NR_CPUS; i++)
atomic_set(&passive_cpu_wait[i], 1);
}
@@ -1475,7 +1475,7 @@ acquirelock:
#ifdef CONFIG_SMP
/* Signal the other CPUs to enter kgdb_wait() */
- if ((!kgdb_single_step || !kgdb_contthread) && kgdb_do_roundup)
+ if ((!kgdb_single_step) && kgdb_do_roundup)
kgdb_roundup_cpus(flags);
#endif
@@ -1494,7 +1494,7 @@ acquirelock:
kgdb_post_primary_code(ks->linux_regs, ks->ex_vector, ks->err_code);
kgdb_deactivate_sw_breakpoints();
kgdb_single_step = 0;
- kgdb_contthread = NULL;
+ kgdb_contthread = current;
exception_level = 0;
/* Talk to debugger with gdbserial protocol */
@@ -1508,7 +1508,7 @@ acquirelock:
kgdb_info[ks->cpu].task = NULL;
atomic_set(&cpu_in_kgdb[ks->cpu], 0);
- if (!kgdb_single_step || !kgdb_contthread) {
+ if (!kgdb_single_step) {
for (i = NR_CPUS-1; i >= 0; i--)
atomic_set(&passive_cpu_wait[i], 0);
/*