3: bld r1, TIF_BREAKPOINT
brcc syscall_exit_cont
- mfsr r3, SYSREG_TLBEHI
- lddsp r2, sp[REG_PC]
- andl r3, 0xff, COH
- lsl r3, 1
- sbr r3, 30
- sbr r3, 0
- mtdr OCD_BWA2A, r2
- mtdr OCD_BWC2A, r3
- rjmp syscall_exit_cont
-
+ rjmp enter_monitor_mode
/* The slow path of the TLB miss handler */
page_table_not_present:
rjmp ret_from_exception
/* This function expects to find offending PC in SYSREG_RAR_EX */
+ .type save_full_context_ex, @function
+ .align 2
save_full_context_ex:
+ mfsr r11, SYSREG_RAR_EX
+ sub r9, pc, . - debug_trampoline
mfsr r8, SYSREG_RSR_EX
+ cp.w r9, r11
+ breq 3f
mov r12, r8
andh r8, (MODE_MASK >> 16), COH
- mfsr r11, SYSREG_RAR_EX
brne 2f
1: pushm r11, r12 /* PC and SR */
stdsp sp[4], r10 /* replace saved SP */
rjmp 1b
+ /*
+ * The debug handler set up a trampoline to make us
+ * automatically enter monitor mode upon return, but since
+ * we're saving the full context, we must assume that the
+ * exception handler might want to alter the return address
+ * and/or status register. So we need to restore the original
+ * context and enter monitor mode manually after the exception
+ * has been handled.
+ */
+3: get_thread_info r8
+ ld.w r11, r8[TI_rar_saved]
+ ld.w r12, r8[TI_rsr_saved]
+ rjmp 1b
+ .size save_full_context_ex, . - save_full_context_ex
+
/* Low-level exception handlers */
handle_critical:
pushm r12
ret_from_exception:
mask_interrupts
lddsp r4, sp[REG_SR]
+
andh r4, (MODE_MASK >> 16), COH
brne fault_resume_kernel
2: bld r1, TIF_BREAKPOINT
brcc fault_resume_user
- mfsr r3, SYSREG_TLBEHI
- lddsp r2, sp[REG_PC]
- andl r3, 0xff, COH
- lsl r3, 1
- sbr r3, 30
- sbr r3, 0
- mtdr OCD_BWA2A, r2
- mtdr OCD_BWC2A, r3
- rjmp fault_resume_user
-
- /* If we get a debug trap from privileged context we end up here */
-handle_debug_priv:
- /* Fix up LR and SP in regs. r1 contains the mode we came from */
- mfsr r2, SYSREG_SR
- mov r3, r2
- bfins r2, r1, SYSREG_MODE_OFFSET, SYSREG_MODE_SIZE
- mtsr SYSREG_SR, r2
+ rjmp enter_monitor_mode
+
+ .section .kprobes.text, "ax", @progbits
+ .type handle_debug, @function
+handle_debug:
+ sub sp, 4 /* r12_orig */
+ stmts --sp, r0-lr
+ mfsr r8, SYSREG_RAR_DBG
+ mfsr r9, SYSREG_RSR_DBG
+ unmask_exceptions
+ pushm r8-r9
+ bfextu r9, r9, SYSREG_MODE_OFFSET, SYSREG_MODE_SIZE
+ brne debug_fixup_regs
+
+.Ldebug_fixup_cont:
+#ifdef CONFIG_TRACE_IRQFLAGS
+ rcall trace_hardirqs_off
+#endif
+ mov r12, sp
+ rcall do_debug
+ mov sp, r12
+
+ lddsp r2, sp[REG_SR]
+ bfextu r3, r2, SYSREG_MODE_OFFSET, SYSREG_MODE_SIZE
+ brne debug_resume_kernel
+
+ get_thread_info r0
+ ld.w r1, r0[TI_flags]
+ mov r2, _TIF_DBGWORK_MASK
+ tst r1, r2
+ brne debug_exit_work
+
+ bld r1, TIF_SINGLE_STEP
+ brcc 1f
+ mfdr r4, OCD_DC
+ sbr r4, OCD_DC_SS_BIT
+ mtdr OCD_DC, r4
+
+1: popm r10,r11
+ mask_exceptions
+ mtsr SYSREG_RSR_DBG, r11
+ mtsr SYSREG_RAR_DBG, r10
+#ifdef CONFIG_TRACE_IRQFLAGS
+ rcall trace_hardirqs_on
+1:
+#endif
+ ldmts sp++, r0-lr
+ sub sp, -4
+ retd
+ .size handle_debug, . - handle_debug
+
+ /* Mode of the trapped context is in r9 */
+ .type debug_fixup_regs, @function
+debug_fixup_regs:
+ mfsr r8, SYSREG_SR
+ mov r10, r8
+ bfins r8, r9, SYSREG_MODE_OFFSET, SYSREG_MODE_SIZE
+ mtsr SYSREG_SR, r8
sub pc, -2
stdsp sp[REG_LR], lr
- mtsr SYSREG_SR, r3
+ mtsr SYSREG_SR, r10
sub pc, -2
- sub r10, sp, -FRAME_SIZE_FULL
- stdsp sp[REG_SP], r10
- mov r12, sp
- rcall do_debug_priv
+ sub r8, sp, -FRAME_SIZE_FULL
+ stdsp sp[REG_SP], r8
+ rjmp .Ldebug_fixup_cont
+ .size debug_fixup_regs, . - debug_fixup_regs
- /* Now, put everything back */
- ssrf SR_EM_BIT
+ .type debug_resume_kernel, @function
+debug_resume_kernel:
+ mask_exceptions
popm r10, r11
mtsr SYSREG_RAR_DBG, r10
mtsr SYSREG_RSR_DBG, r11
1:
#endif
mfsr r2, SYSREG_SR
- mov r3, r2
- bfins r2, r1, SYSREG_MODE_OFFSET, SYSREG_MODE_SIZE
+ mov r1, r2
+ bfins r2, r3, SYSREG_MODE_OFFSET, SYSREG_MODE_SIZE
mtsr SYSREG_SR, r2
sub pc, -2
popm lr
- mtsr SYSREG_SR, r3
+ mtsr SYSREG_SR, r1
sub pc, -2
sub sp, -4 /* skip SP */
popm r0-r12
sub sp, -4
retd
+ .size debug_resume_kernel, . - debug_resume_kernel
+ .type debug_exit_work, @function
+debug_exit_work:
/*
- * At this point, everything is masked, that is, interrupts,
- * exceptions and debugging traps. We might get called from
- * interrupt or exception context in some rare cases, but this
- * will be taken care of by do_debug(), so we're not going to
- * do a 100% correct context save here.
+ * We must return from Monitor Mode using a retd, and we must
+ * not schedule since that involves the D bit in SR getting
+ * cleared by something other than the debug hardware. This
+ * may cause undefined behaviour according to the Architecture
+ * manual.
+ *
+ * So we fix up the return address and status and return to a
+ * stub below in Exception mode. From there, we can follow the
+ * normal exception return path.
+ *
+ * The real return address and status registers are stored on
+ * the stack in the way the exception return path understands,
+ * so no need to fix anything up there.
*/
-handle_debug:
- sub sp, 4 /* r12_orig */
- stmts --sp, r0-lr
- mfsr r0, SYSREG_RAR_DBG
- mfsr r1, SYSREG_RSR_DBG
-#ifdef CONFIG_TRACE_IRQFLAGS
- rcall trace_hardirqs_off
-#endif
- unmask_exceptions
- stm --sp, r0, r1
- bfextu r1, r1, SYSREG_MODE_OFFSET, SYSREG_MODE_SIZE
- brne handle_debug_priv
-
- mov r12, sp
- rcall do_debug
-
- lddsp r10, sp[REG_SR]
- andh r10, (MODE_MASK >> 16), COH
- breq debug_resume_user
-
-debug_restore_all:
- popm r10,r11
- mask_exceptions
- mtsr SYSREG_RSR_DBG, r11
- mtsr SYSREG_RAR_DBG, r10
-#ifdef CONFIG_TRACE_IRQFLAGS
- bld r11, SYSREG_GM_OFFSET
- brcc 1f
- rcall trace_hardirqs_on
-1:
-#endif
- ldmts sp++, r0-lr
- sub sp, -4
+ sub r8, pc, . - fault_exit_work
+ mtsr SYSREG_RAR_DBG, r8
+ mov r9, 0
+ orh r9, hi(SR_EM | SR_GM | MODE_EXCEPTION)
+ mtsr SYSREG_RSR_DBG, r9
+ sub pc, -2
retd
-
-debug_resume_user:
- get_thread_info r0
- mask_interrupts
-
- ld.w r1, r0[TI_flags]
- andl r1, _TIF_DBGWORK_MASK, COH
- breq debug_restore_all
-
-1: bld r1, TIF_NEED_RESCHED
- brcc 2f
- unmask_interrupts
- rcall schedule
- mask_interrupts
- ld.w r1, r0[TI_flags]
- rjmp 1b
-
-2: mov r2, _TIF_SIGPENDING | _TIF_RESTORE_SIGMASK
- tst r1, r2
- breq 3f
- unmask_interrupts
- mov r12, sp
- mov r11, r0
- rcall do_notify_resume
- mask_interrupts
- ld.w r1, r0[TI_flags]
- rjmp 1b
-
-3: bld r1, TIF_SINGLE_STEP
- brcc debug_restore_all
- mfdr r2, OCD_DC
- sbr r2, OCD_DC_SS_BIT
- mtdr OCD_DC, r2
- rjmp debug_restore_all
+ .size debug_exit_work, . - debug_exit_work
.set rsr_int0, SYSREG_RSR_INT0
.set rsr_int1, SYSREG_RSR_INT1
IRQ_LEVEL 1
IRQ_LEVEL 2
IRQ_LEVEL 3
+
+ .section .kprobes.text, "ax", @progbits
+ .type enter_monitor_mode, @function
+enter_monitor_mode:
+ /*
+ * We need to enter monitor mode to do a single step. The
+ * monitor code will alter the return address so that we
+ * return directly to the user instead of returning here.
+ */
+ breakpoint
+ rjmp breakpoint_failed
+
+ .size enter_monitor_mode, . - enter_monitor_mode
+
+ .type debug_trampoline, @function
+ .global debug_trampoline
+debug_trampoline:
+ /*
+ * Save the registers on the stack so that the monitor code
+ * can find them easily.
+ */
+ sub sp, 4 /* r12_orig */
+ stmts --sp, r0-lr
+ get_thread_info r0
+ ld.w r8, r0[TI_rar_saved]
+ ld.w r9, r0[TI_rsr_saved]
+ pushm r8-r9
+
+ /*
+ * The monitor code will alter the return address so we don't
+ * return here.
+ */
+ breakpoint
+ rjmp breakpoint_failed
+ .size debug_trampoline, . - debug_trampoline
+
+ .type breakpoint_failed, @function
+breakpoint_failed:
+ /*
+ * Something went wrong. Perhaps the debug hardware isn't
+ * enabled?
+ */
+ lda.w r12, msg_breakpoint_failed
+ mov r11, sp
+ mov r10, 9 /* SIGKILL */
+ call die
+1: rjmp 1b
+
+msg_breakpoint_failed:
+ .asciz "Failed to enter Debug Mode"
static void ptrace_single_step(struct task_struct *tsk)
{
- pr_debug("ptrace_single_step: pid=%u, SR=0x%08lx\n",
- tsk->pid, tsk->thread.cpu_context.sr);
- if (!(tsk->thread.cpu_context.sr & SR_D)) {
- /*
- * Set a breakpoint at the current pc to force the
- * process into debug mode. The syscall/exception
- * exit code will set a breakpoint at the return
- * address when this flag is set.
- */
- pr_debug("ptrace_single_step: Setting TIF_BREAKPOINT\n");
- set_tsk_thread_flag(tsk, TIF_BREAKPOINT);
- }
+ pr_debug("ptrace_single_step: pid=%u, PC=0x%08lx, SR=0x%08lx\n",
+ tsk->pid, task_pt_regs(tsk)->pc, task_pt_regs(tsk)->sr);
- /* The monitor code will do the actual step for us */
+ /*
+ * We can't schedule in Debug mode, so when TIF_BREAKPOINT is
+ * set, the system call or exception handler will do a
+ * breakpoint to enter monitor mode before returning to
+ * userspace.
+ *
+ * The monitor code will then notice that TIF_SINGLE_STEP is
+ * set and return to userspace with single stepping enabled.
+ * The CPU will then enter monitor mode again after exactly
+ * one instruction has been executed, and the monitor code
+ * will then send a SIGTRAP to the process.
+ */
+ set_tsk_thread_flag(tsk, TIF_BREAKPOINT);
set_tsk_thread_flag(tsk, TIF_SINGLE_STEP);
}
void ptrace_disable(struct task_struct *child)
{
clear_tsk_thread_flag(child, TIF_SINGLE_STEP);
-}
-
-/*
- * Handle hitting a breakpoint
- */
-static void ptrace_break(struct task_struct *tsk, struct pt_regs *regs)
-{
- siginfo_t info;
-
- info.si_signo = SIGTRAP;
- info.si_errno = 0;
- info.si_code = TRAP_BRKPT;
- info.si_addr = (void __user *)instruction_pointer(regs);
-
- pr_debug("ptrace_break: Sending SIGTRAP to PID %u (pc = 0x%p)\n",
- tsk->pid, info.si_addr);
- force_sig_info(SIGTRAP, &info, tsk);
+ clear_tsk_thread_flag(child, TIF_BREAKPOINT);
}
/*
unsigned long *regs;
unsigned long value;
- pr_debug("ptrace_read_user(%p, %#lx, %p)\n",
- tsk, offset, data);
-
if (offset & 3 || offset >= sizeof(struct user)) {
printk("ptrace_read_user: invalid offset 0x%08lx\n", offset);
return -EIO;
if (offset < sizeof(struct pt_regs))
value = regs[offset / sizeof(regs[0])];
+ pr_debug("ptrace_read_user(%s[%u], %#lx, %p) -> %#lx\n",
+ tsk->comm, tsk->pid, offset, data, value);
+
return put_user(value, data);
}
{
unsigned long *regs;
+ pr_debug("ptrace_write_user(%s[%u], %#lx, %#lx)\n",
+ tsk->comm, tsk->pid, offset, value);
+
if (offset & 3 || offset >= sizeof(struct user)) {
- printk("ptrace_write_user: invalid offset 0x%08lx\n", offset);
+ pr_debug(" invalid offset 0x%08lx\n", offset);
return -EIO;
}
{
int ret;
- pr_debug("arch_ptrace(%ld, %d, %#lx, %#lx)\n",
- request, child->pid, addr, data);
-
pr_debug("ptrace: Enabling monitor mode...\n");
ocd_write(DC, ocd_read(DC) | (1 << OCD_DC_MM_BIT)
| (1 << OCD_DC_DBE_BIT));
break;
}
- pr_debug("sys_ptrace returning %d (DC = 0x%08lx)\n",
- ret, ocd_read(DC));
return ret;
}
asmlinkage void syscall_trace(void)
{
- pr_debug("syscall_trace called\n");
if (!test_thread_flag(TIF_SYSCALL_TRACE))
return;
if (!(current->ptrace & PT_PTRACED))
return;
- pr_debug("syscall_trace: notifying parent\n");
/* The 0x80 provides a way for the tracing parent to
* distinguish between a syscall stop and SIGTRAP delivery */
ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
}
}
-asmlinkage void do_debug_priv(struct pt_regs *regs)
-{
- unsigned long dc, ds;
- unsigned long die_val;
-
- ds = ocd_read(DS);
-
- pr_debug("do_debug_priv: pc = %08lx, ds = %08lx\n", regs->pc, ds);
-
- if (ds & (1 << OCD_DS_SSS_BIT))
- die_val = DIE_SSTEP;
- else
- die_val = DIE_BREAKPOINT;
-
- if (notify_die(die_val, "ptrace", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
- return;
-
- if (likely(ds & (1 << OCD_DS_SSS_BIT))) {
- extern void itlb_miss(void);
- extern void tlb_miss_common(void);
- struct thread_info *ti;
-
- dc = ocd_read(DC);
- dc &= ~(1 << OCD_DC_SS_BIT);
- ocd_write(DC, dc);
-
- ti = current_thread_info();
- set_ti_thread_flag(ti, TIF_BREAKPOINT);
-
- /* The TLB miss handlers don't check thread flags */
- if ((regs->pc >= (unsigned long)&itlb_miss)
- && (regs->pc <= (unsigned long)&tlb_miss_common)) {
- ocd_write(BWA2A, sysreg_read(RAR_EX));
- ocd_write(BWC2A, 0x40000001 | (get_asid() << 1));
- }
-
- /*
- * If we're running in supervisor mode, the breakpoint
- * will take us where we want directly, no need to
- * single step.
- */
- if ((regs->sr & MODE_MASK) != MODE_SUPERVISOR)
- set_ti_thread_flag(ti, TIF_SINGLE_STEP);
- } else {
- panic("Unable to handle debug trap at pc = %08lx\n",
- regs->pc);
- }
-}
-
/*
- * Handle breakpoints, single steps and other debuggy things. To keep
- * things simple initially, we run with interrupts and exceptions
- * disabled all the time.
+ * debug_trampoline() is an assembly stub which will store all user
+ * registers on the stack and execute a breakpoint instruction.
+ *
+ * If we single-step into an exception handler which runs with
+ * interrupts disabled the whole time so it doesn't have to check for
+ * pending work, its return address will be modified so that it ends
+ * up returning to debug_trampoline.
+ *
+ * If the exception handler decides to store the user context and
+ * enable interrupts after all, it will restore the original return
+ * address and status register value. Before it returns, it will
+ * notice that TIF_BREAKPOINT is set and execute a breakpoint
+ * instruction.
*/
-asmlinkage void do_debug(struct pt_regs *regs)
-{
- unsigned long dc, ds;
+extern void debug_trampoline(void);
- ds = ocd_read(DS);
- pr_debug("do_debug: pc = %08lx, ds = %08lx\n", regs->pc, ds);
+asmlinkage struct pt_regs *do_debug(struct pt_regs *regs)
+{
+ struct thread_info *ti;
+ unsigned long trampoline_addr;
+ u32 status;
+ u32 ctrl;
+ int code;
+
+ status = ocd_read(DS);
+ ti = current_thread_info();
+ code = TRAP_BRKPT;
+
+ pr_debug("do_debug: status=0x%08x PC=0x%08lx SR=0x%08lx tif=0x%08lx\n",
+ status, regs->pc, regs->sr, ti->flags);
+
+ if (!user_mode(regs)) {
+ unsigned long die_val = DIE_BREAKPOINT;
+
+ if (status & (1 << OCD_DS_SSS_BIT))
+ die_val = DIE_SSTEP;
+
+ if (notify_die(die_val, "ptrace", regs, 0, 0, SIGTRAP)
+ == NOTIFY_STOP)
+ return regs;
+
+ if ((status & (1 << OCD_DS_SWB_BIT))
+ && test_and_clear_ti_thread_flag(
+ ti, TIF_BREAKPOINT)) {
+ /*
+ * Explicit breakpoint from trampoline or
+ * exception/syscall/interrupt handler.
+ *
+ * The real saved regs are on the stack right
+ * after the ones we saved on entry.
+ */
+ regs++;
+ pr_debug(" -> TIF_BREAKPOINT done, adjusted regs:"
+ "PC=0x%08lx SR=0x%08lx\n",
+ regs->pc, regs->sr);
+ BUG_ON(!user_mode(regs));
+
+ if (test_thread_flag(TIF_SINGLE_STEP)) {
+ pr_debug("Going to do single step...\n");
+ return regs;
+ }
+
+ /*
+ * No TIF_SINGLE_STEP means we're done
+ * stepping over a syscall. Do the trap now.
+ */
+ code = TRAP_TRACE;
+ } else if ((status & (1 << OCD_DS_SSS_BIT))
+ && test_ti_thread_flag(ti, TIF_SINGLE_STEP)) {
+
+ pr_debug("Stepped into something, "
+ "setting TIF_BREAKPOINT...\n");
+ set_ti_thread_flag(ti, TIF_BREAKPOINT);
+
+ /*
+ * We stepped into an exception, interrupt or
+ * syscall handler. Some exception handlers
+ * don't check for pending work, so we need to
+ * set up a trampoline just in case.
+ *
+ * The exception entry code will undo the
+ * trampoline stuff if it does a full context
+ * save (which also means that it'll check for
+ * pending work later.)
+ */
+ if ((regs->sr & MODE_MASK) == MODE_EXCEPTION) {
+ trampoline_addr
+ = (unsigned long)&debug_trampoline;
+
+ pr_debug("Setting up trampoline...\n");
+ ti->rar_saved = sysreg_read(RAR_EX);
+ ti->rsr_saved = sysreg_read(RSR_EX);
+ sysreg_write(RAR_EX, trampoline_addr);
+ sysreg_write(RSR_EX, (MODE_EXCEPTION
+ | SR_EM | SR_GM));
+ BUG_ON(ti->rsr_saved & MODE_MASK);
+ }
+
+ /*
+ * If we stepped into a system call, we
+ * shouldn't do a single step after we return
+ * since the return address is right after the
+ * "scall" instruction we were told to step
+ * over.
+ */
+ if ((regs->sr & MODE_MASK) == MODE_SUPERVISOR) {
+ pr_debug("Supervisor; no single step\n");
+ clear_ti_thread_flag(ti, TIF_SINGLE_STEP);
+ }
+
+ ctrl = ocd_read(DC);
+ ctrl &= ~(1 << OCD_DC_SS_BIT);
+ ocd_write(DC, ctrl);
+
+ return regs;
+ } else {
+ printk(KERN_ERR "Unexpected OCD_DS value: 0x%08x\n",
+ status);
+ printk(KERN_ERR "Thread flags: 0x%08lx\n", ti->flags);
+ die("Unhandled debug trap in kernel mode",
+ regs, SIGTRAP);
+ }
+ } else if (status & (1 << OCD_DS_SSS_BIT)) {
+ /* Single step in user mode */
+ code = TRAP_TRACE;
- if (test_thread_flag(TIF_BREAKPOINT)) {
- pr_debug("TIF_BREAKPOINT set\n");
- /* We're taking care of it */
- clear_thread_flag(TIF_BREAKPOINT);
- ocd_write(BWC2A, 0);
+ ctrl = ocd_read(DC);
+ ctrl &= ~(1 << OCD_DC_SS_BIT);
+ ocd_write(DC, ctrl);
}
- if (test_thread_flag(TIF_SINGLE_STEP)) {
- pr_debug("TIF_SINGLE_STEP set, ds = 0x%08lx\n", ds);
- if (ds & (1 << OCD_DS_SSS_BIT)) {
- dc = ocd_read(DC);
- dc &= ~(1 << OCD_DC_SS_BIT);
- ocd_write(DC, dc);
+ pr_debug("Sending SIGTRAP: code=%d PC=0x%08lx SR=0x%08lx\n",
+ code, regs->pc, regs->sr);
- clear_thread_flag(TIF_SINGLE_STEP);
- ptrace_break(current, regs);
- }
- } else {
- /* regular breakpoint */
- ptrace_break(current, regs);
- }
+ clear_thread_flag(TIF_SINGLE_STEP);
+ _exception(SIGTRAP, regs, code, instruction_pointer(regs));
+
+ return regs;
}
projects / linux-2.6 / commitdiff