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kgdb, x86, arm, mips, powerpc: ignore user space single stepping

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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>
This commit is contained in:
Jason Wessel
2008-09-26 10:36:41 -05:00
parent 18d6522b86
commit d7161a6534
5 changed files with 18 additions and 18 deletions
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8
kernel/kgdb.c
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@@ -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);
/*