diff options
| author | Paul Mackerras <paulus@samba.org> | 2010-06-23 15:42:43 +1000 |
|---|---|---|
| committer | Paul Mackerras <paulus@samba.org> | 2010-06-23 15:42:43 +1000 |
| commit | 574cb24899d35e71be1d8fb1add2c3306804e4bf (patch) | |
| tree | 4ef17bc8d4fa83448282d0f3a463e3fe2377078f | |
| parent | e3e94084adb5610987283367574ebc771e8206e1 (diff) | |
powerpc, hw_breakpoint: Fix off-by-one in checking access address
The code would accept an access to an address one byte past the end
of the requested range as legitimate, due to having a "<=" rather than
a "<". This fixes that and cleans up the code a bit.
Signed-off-by: Paul Mackerras <paulus@samba.org>
| -rw-r--r-- | arch/powerpc/kernel/hw_breakpoint.c | 23 |
1 files changed, 7 insertions, 16 deletions
diff --git a/arch/powerpc/kernel/hw_breakpoint.c b/arch/powerpc/kernel/hw_breakpoint.c index ed39805a3b84..241e09712314 100644 --- a/arch/powerpc/kernel/hw_breakpoint.c +++ b/arch/powerpc/kernel/hw_breakpoint.c @@ -197,7 +197,6 @@ void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs) */ int __kprobes hw_breakpoint_handler(struct die_args *args) { - bool is_ptrace_bp = false; int rc = NOTIFY_STOP; struct perf_event *bp; struct pt_regs *regs = args->regs; @@ -208,6 +207,7 @@ int __kprobes hw_breakpoint_handler(struct die_args *args) /* Disable breakpoints during exception handling */ set_dabr(0); + /* * The counter may be concurrently released but that can only * occur from a call_rcu() path. We can then safely fetch @@ -220,8 +220,6 @@ int __kprobes hw_breakpoint_handler(struct die_args *args) if (!bp) goto out; info = counter_arch_bp(bp); - is_ptrace_bp = (bp->overflow_handler == ptrace_triggered) ? - true : false; /* * Return early after invoking user-callback function without restoring @@ -229,7 +227,7 @@ int __kprobes hw_breakpoint_handler(struct die_args *args) * one-shot mode. The ptrace-ed process will receive the SIGTRAP signal * generated in do_dabr(). */ - if (is_ptrace_bp) { + if (bp->overflow_handler == ptrace_triggered) { perf_bp_event(bp, regs); rc = NOTIFY_DONE; goto out; @@ -237,19 +235,12 @@ int __kprobes hw_breakpoint_handler(struct die_args *args) /* * Verify if dar lies within the address range occupied by the symbol - * being watched to filter extraneous exceptions. + * being watched to filter extraneous exceptions. If it doesn't, + * we still need to single-step the instruction, but we don't + * generate an event. */ - if (!((bp->attr.bp_addr <= dar) && - (dar <= (bp->attr.bp_addr + bp->attr.bp_len)))) { - /* - * This exception is triggered not because of a memory access - * on the monitored variable but in the double-word address - * range in which it is contained. We will consume this - * exception, considering it as 'noise'. - */ - info->extraneous_interrupt = true; - } else - info->extraneous_interrupt = false; + info->extraneous_interrupt = !((bp->attr.bp_addr <= dar) && + (dar - bp->attr.bp_addr < bp->attr.bp_len)); /* Do not emulate user-space instructions, instead single-step them */ if (user_mode(regs)) { |