The patch titled
Subject: ptrace: PTRACE_DETACH should do flush_ptrace_hw_breakpoint(child)
has been added to the -mm tree. Its filename is
ptrace-ptrace_detach-should-do-flush_ptrace_hw_breakpointchild.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: ptrace: PTRACE_DETACH should do flush_ptrace_hw_breakpoint(child)
Change ptrace_detach() to call flush_ptrace_hw_breakpoint(child). This
frees the slots for non-ptrace PERF_TYPE_BREAKPOINT users, and this
ensures that the tracee won't be killed by SIGTRAP triggered by the active
breakpoints.
Test-case:
unsigned long encode_dr7(int drnum, int enable, unsigned int type, unsigned int len)
{
unsigned long dr7;
dr7 = ((len | type) & 0xf)
<< (DR_CONTROL_SHIFT + drnum * DR_CONTROL_SIZE);
if (enable)
dr7 |= (DR_GLOBAL_ENABLE << (drnum * DR_ENABLE_SIZE));
return dr7;
}
int write_dr(int pid, int dr, unsigned long val)
{
return ptrace(PTRACE_POKEUSER, pid,
offsetof (struct user, u_debugreg[dr]),
val);
}
void func(void)
{
}
int main(void)
{
int pid, stat;
unsigned long dr7;
pid = fork();
if (!pid) {
assert(ptrace(PTRACE_TRACEME, 0,0,0) == 0);
kill(getpid(), SIGHUP);
func();
return 0x13;
}
assert(pid == waitpid(-1, &stat, 0));
assert(WSTOPSIG(stat) == SIGHUP);
assert(write_dr(pid, 0, (long)func) == 0);
dr7 = encode_dr7(0, 1, DR_RW_EXECUTE, DR_LEN_1);
assert(write_dr(pid, 7, dr7) == 0);
assert(ptrace(PTRACE_DETACH, pid, 0,0) == 0);
assert(pid == waitpid(-1, &stat, 0));
assert(stat == 0x1300);
return 0;
}
Before this patch the child is killed after PTRACE_DETACH.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Acked-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jan Kratochvil <jan.kratochvil@xxxxxxxxxx>
Cc: Michael Neuling <mikey@xxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Paul Mundt <lethal@xxxxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Prasad <prasad@xxxxxxxxxxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/ptrace.c | 1 +
1 file changed, 1 insertion(+)
diff -puN kernel/ptrace.c~ptrace-ptrace_detach-should-do-flush_ptrace_hw_breakpointchild kernel/ptrace.c
--- a/kernel/ptrace.c~ptrace-ptrace_detach-should-do-flush_ptrace_hw_breakpointchild
+++ a/kernel/ptrace.c
@@ -469,6 +469,7 @@ static int ptrace_detach(struct task_str
/* Architecture-specific hardware disable .. */
ptrace_disable(child);
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+ flush_ptrace_hw_breakpoint(child);
write_lock_irq(&tasklist_lock);
/*
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
posix_cpu_timer-consolidate-expiry-time-type.patch
posix_cpu_timers-consolidate-timer-list-cleanups.patch
posix_cpu_timers-consolidate-expired-timers-check.patch
posix-timers-correctly-get-dying-task-time-sample-in-posix_cpu_timer_schedule.patch
posix_timers-fix-racy-timer-delta-caching-on-task-exit.patch
lockdep-introduce-lock_acquire_exclusive-shared-helper-macros.patch
lglock-update-lockdep-annotations-to-report-recursive-local-locks.patch
autofs4-allow-autofs-to-work-outside-the-initial-pid-namespace.patch
autofs4-translate-pids-to-the-right-namespace-for-the-daemon.patch
ptrace-x86-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch
ptrace-powerpc-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch
ptrace-arm-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch
ptrace-sh-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch
ptrace-revert-prepare-to-fix-racy-accesses-on-task-breakpoints.patch
ptrace-x86-simplify-the-disable-logic-in-ptrace_write_dr7.patch
ptrace-x86-dont-delay-disable-till-second-pass-in-ptrace_write_dr7.patch
ptrace-x86-introduce-ptrace_register_breakpoint.patch
ptrace-x86-ptrace_write_dr7-should-create-bp-if-disabled.patch
ptrace-x86-cleanup-ptrace_set_debugreg.patch
ptrace-ptrace_detach-should-do-flush_ptrace_hw_breakpointchild.patch
ptrace-x86-flush_ptrace_hw_breakpoint-shoule-clear-the-virtual-debug-registers.patch
x86-kill-tif_debug.patch
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