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| author | Jason Wessel <jason.wessel@windriver.com> | 2008-09-26 15:36:41 (GMT) |
|---|---|---|
| committer | Jason Wessel <jason.wessel@windriver.com> | 2008-09-26 15:36:41 (GMT) |
| commit | d7161a65341556bacb5e6654e133803f46f51063 (patch) | |
| tree | b2933dc2ce1435956c193c37fd53a3d5530fe9d7 /arch/x86 | |
| parent | 18d6522b86d21a04c8ac1ea79747e2e434a956d9 (diff) | |
| download | linux-d7161a65341556bacb5e6654e133803f46f51063.tar.xz | |
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>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kernel/kgdb.c | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c index f47f0eb..00f7896 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)) |