![Paul Gortmaker](/assets/img/avatar_default.png)
Currently, on 8641D, which doesn't set CONFIG_HAVE_HW_BREAKPOINT we get the following splat: BUG: using smp_processor_id() in preemptible [00000000] code: login/1382 caller is set_breakpoint+0x1c/0xa0 CPU: 0 PID: 1382 Comm: login Not tainted 3.15.0-rc3-00041-g2aafe1a4d451 #1 Call Trace: [decd5d80] [c0008dc4] show_stack+0x50/0x158 (unreliable) [decd5dc0] [c03c6fa0] dump_stack+0x7c/0xdc [decd5de0] [c01f8818] check_preemption_disabled+0xf4/0x104 [decd5e00] [c00086b8] set_breakpoint+0x1c/0xa0 [decd5e10] [c00d4530] flush_old_exec+0x2bc/0x588 [decd5e40] [c011c468] load_elf_binary+0x2ac/0x1164 [decd5ec0] [c00d35f8] search_binary_handler+0xc4/0x1f8 [decd5ef0] [c00d4ee8] do_execve+0x3d8/0x4b8 [decd5f40] [c001185c] ret_from_syscall+0x0/0x38 --- Exception: c01 at 0xfeee554 LR = 0xfeee7d4 The call path in this case is: flush_thread --> set_debug_reg_defaults --> set_breakpoint --> __get_cpu_var Since preemption is enabled in the cleanup of flush thread, and there is no need to disable it, introduce the distinction between set_breakpoint and __set_breakpoint, leaving only the flush_thread instance as the current user of set_breakpoint. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
213 lines
5.7 KiB
C
213 lines
5.7 KiB
C
/*
|
|
* Common signal handling code for both 32 and 64 bits
|
|
*
|
|
* Copyright (c) 2007 Benjamin Herrenschmidt, IBM Coproration
|
|
* Extracted from signal_32.c and signal_64.c
|
|
*
|
|
* This file is subject to the terms and conditions of the GNU General
|
|
* Public License. See the file README.legal in the main directory of
|
|
* this archive for more details.
|
|
*/
|
|
|
|
#include <linux/tracehook.h>
|
|
#include <linux/signal.h>
|
|
#include <linux/uprobes.h>
|
|
#include <linux/key.h>
|
|
#include <linux/context_tracking.h>
|
|
#include <asm/hw_breakpoint.h>
|
|
#include <asm/uaccess.h>
|
|
#include <asm/unistd.h>
|
|
#include <asm/debug.h>
|
|
#include <asm/tm.h>
|
|
|
|
#include "signal.h"
|
|
|
|
/* Log an error when sending an unhandled signal to a process. Controlled
|
|
* through debug.exception-trace sysctl.
|
|
*/
|
|
|
|
int show_unhandled_signals = 1;
|
|
|
|
/*
|
|
* Allocate space for the signal frame
|
|
*/
|
|
void __user * get_sigframe(struct k_sigaction *ka, unsigned long sp,
|
|
size_t frame_size, int is_32)
|
|
{
|
|
unsigned long oldsp, newsp;
|
|
|
|
/* Default to using normal stack */
|
|
oldsp = get_clean_sp(sp, is_32);
|
|
|
|
/* Check for alt stack */
|
|
if ((ka->sa.sa_flags & SA_ONSTACK) &&
|
|
current->sas_ss_size && !on_sig_stack(oldsp))
|
|
oldsp = (current->sas_ss_sp + current->sas_ss_size);
|
|
|
|
/* Get aligned frame */
|
|
newsp = (oldsp - frame_size) & ~0xFUL;
|
|
|
|
/* Check access */
|
|
if (!access_ok(VERIFY_WRITE, (void __user *)newsp, oldsp - newsp))
|
|
return NULL;
|
|
|
|
return (void __user *)newsp;
|
|
}
|
|
|
|
static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
|
|
int has_handler)
|
|
{
|
|
unsigned long ret = regs->gpr[3];
|
|
int restart = 1;
|
|
|
|
/* syscall ? */
|
|
if (TRAP(regs) != 0x0C00)
|
|
return;
|
|
|
|
/* error signalled ? */
|
|
if (!(regs->ccr & 0x10000000))
|
|
return;
|
|
|
|
switch (ret) {
|
|
case ERESTART_RESTARTBLOCK:
|
|
case ERESTARTNOHAND:
|
|
/* ERESTARTNOHAND means that the syscall should only be
|
|
* restarted if there was no handler for the signal, and since
|
|
* we only get here if there is a handler, we dont restart.
|
|
*/
|
|
restart = !has_handler;
|
|
break;
|
|
case ERESTARTSYS:
|
|
/* ERESTARTSYS means to restart the syscall if there is no
|
|
* handler or the handler was registered with SA_RESTART
|
|
*/
|
|
restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0;
|
|
break;
|
|
case ERESTARTNOINTR:
|
|
/* ERESTARTNOINTR means that the syscall should be
|
|
* called again after the signal handler returns.
|
|
*/
|
|
break;
|
|
default:
|
|
return;
|
|
}
|
|
if (restart) {
|
|
if (ret == ERESTART_RESTARTBLOCK)
|
|
regs->gpr[0] = __NR_restart_syscall;
|
|
else
|
|
regs->gpr[3] = regs->orig_gpr3;
|
|
regs->nip -= 4;
|
|
regs->result = 0;
|
|
} else {
|
|
regs->result = -EINTR;
|
|
regs->gpr[3] = EINTR;
|
|
regs->ccr |= 0x10000000;
|
|
}
|
|
}
|
|
|
|
static int do_signal(struct pt_regs *regs)
|
|
{
|
|
sigset_t *oldset = sigmask_to_save();
|
|
siginfo_t info;
|
|
int signr;
|
|
struct k_sigaction ka;
|
|
int ret;
|
|
int is32 = is_32bit_task();
|
|
|
|
signr = get_signal_to_deliver(&info, &ka, regs, NULL);
|
|
|
|
/* Is there any syscall restart business here ? */
|
|
check_syscall_restart(regs, &ka, signr > 0);
|
|
|
|
if (signr <= 0) {
|
|
/* No signal to deliver -- put the saved sigmask back */
|
|
restore_saved_sigmask();
|
|
regs->trap = 0;
|
|
return 0; /* no signals delivered */
|
|
}
|
|
|
|
#ifndef CONFIG_PPC_ADV_DEBUG_REGS
|
|
/*
|
|
* Reenable the DABR before delivering the signal to
|
|
* user space. The DABR will have been cleared if it
|
|
* triggered inside the kernel.
|
|
*/
|
|
if (current->thread.hw_brk.address &&
|
|
current->thread.hw_brk.type)
|
|
__set_breakpoint(¤t->thread.hw_brk);
|
|
#endif
|
|
/* Re-enable the breakpoints for the signal stack */
|
|
thread_change_pc(current, regs);
|
|
|
|
if (is32) {
|
|
if (ka.sa.sa_flags & SA_SIGINFO)
|
|
ret = handle_rt_signal32(signr, &ka, &info, oldset,
|
|
regs);
|
|
else
|
|
ret = handle_signal32(signr, &ka, &info, oldset,
|
|
regs);
|
|
} else {
|
|
ret = handle_rt_signal64(signr, &ka, &info, oldset, regs);
|
|
}
|
|
|
|
regs->trap = 0;
|
|
if (ret) {
|
|
signal_delivered(signr, &info, &ka, regs,
|
|
test_thread_flag(TIF_SINGLESTEP));
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
|
|
{
|
|
user_exit();
|
|
|
|
if (thread_info_flags & _TIF_UPROBE)
|
|
uprobe_notify_resume(regs);
|
|
|
|
if (thread_info_flags & _TIF_SIGPENDING)
|
|
do_signal(regs);
|
|
|
|
if (thread_info_flags & _TIF_NOTIFY_RESUME) {
|
|
clear_thread_flag(TIF_NOTIFY_RESUME);
|
|
tracehook_notify_resume(regs);
|
|
}
|
|
|
|
user_enter();
|
|
}
|
|
|
|
unsigned long get_tm_stackpointer(struct pt_regs *regs)
|
|
{
|
|
/* When in an active transaction that takes a signal, we need to be
|
|
* careful with the stack. It's possible that the stack has moved back
|
|
* up after the tbegin. The obvious case here is when the tbegin is
|
|
* called inside a function that returns before a tend. In this case,
|
|
* the stack is part of the checkpointed transactional memory state.
|
|
* If we write over this non transactionally or in suspend, we are in
|
|
* trouble because if we get a tm abort, the program counter and stack
|
|
* pointer will be back at the tbegin but our in memory stack won't be
|
|
* valid anymore.
|
|
*
|
|
* To avoid this, when taking a signal in an active transaction, we
|
|
* need to use the stack pointer from the checkpointed state, rather
|
|
* than the speculated state. This ensures that the signal context
|
|
* (written tm suspended) will be written below the stack required for
|
|
* the rollback. The transaction is aborted becuase of the treclaim,
|
|
* so any memory written between the tbegin and the signal will be
|
|
* rolled back anyway.
|
|
*
|
|
* For signals taken in non-TM or suspended mode, we use the
|
|
* normal/non-checkpointed stack pointer.
|
|
*/
|
|
|
|
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
|
|
if (MSR_TM_ACTIVE(regs->msr)) {
|
|
tm_reclaim_current(TM_CAUSE_SIGNAL);
|
|
if (MSR_TM_TRANSACTIONAL(regs->msr))
|
|
return current->thread.ckpt_regs.gpr[1];
|
|
}
|
|
#endif
|
|
return regs->gpr[1];
|
|
}
|