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![Jiang Lu](/assets/img/avatar_default.png)
A page fault occurred during reading user stack in oprofile backtrace would lead following calltrace: WARNING: at linux/kernel/smp.c:210 Modules linked in: CPU: 5 PID: 736 Comm: sh Tainted: G W 3.14.23-WR7.0.0.0_standard #1 task: c0000000f6208bc0 ti: c00000007c72c000 task.ti: c00000007c72c000 NIP: c0000000000ed6e4 LR: c0000000000ed5b8 CTR: 0000000000000000 REGS: c00000007c72f050 TRAP: 0700 Tainted: G W (3.14.23-WR7.0.0 tandard) MSR: 0000000080021000 <CE,ME> CR: 48222482 XER: 00000000 SOFTE: 0 GPR00: c0000000000ed5b8 c00000007c72f2d0 c0000000010aa048 0000000000000005 GPR04: c000000000fdb820 c00000007c72f410 0000000000000001 0000000000000005 GPR08: c0000000010b5768 c000000000f8a048 0000000000000001 0000000000000000 GPR12: 0000000048222482 c00000000fffe580 0000000022222222 0000000010129664 GPR16: 0000000010143cc0 0000000000000000 0000000044444444 0000000000000000 GPR20: c00000007c7221d8 c0000000f638e3c8 000003f15a20120d 0000000000000001 GPR24: 000000005a20120d c00000007c722000 c00000007cdedda8 00003fffef23b160 GPR28: 0000000000000001 c00000007c72f410 c000000000fdb820 0000000000000006 NIP [c0000000000ed6e4] .smp_call_function_single+0x18c/0x248 LR [c0000000000ed5b8] .smp_call_function_single+0x60/0x248 Call Trace: [c00000007c72f2d0] [c0000000000ed5b8] .smp_call_function_single+0x60/0x248 (unreliable) [c00000007c72f3a0] [c000000000030810] .__flush_tlb_page+0x164/0x1b0 [c00000007c72f460] [c00000000002e054] .ptep_set_access_flags+0xb8/0x168 [c00000007c72f500] [c0000000001ad3d8] .handle_mm_fault+0x4a8/0xbac [c00000007c72f5e0] [c000000000bb3238] .do_page_fault+0x3b8/0x868 [c00000007c72f810] [c00000000001e1d0] storage_fault_common+0x20/0x44 Exception: 301 at .__copy_tofrom_user_base+0x54/0x5b0 LR = .op_powerpc_backtrace+0x190/0x20c [c00000007c72fb00] [c000000000a2ec34] .op_powerpc_backtrace+0x204/0x20c (unreliable) [c00000007c72fbc0] [c000000000a2b5fc] .oprofile_add_ext_sample+0xe8/0x118 [c00000007c72fc70] [c000000000a2eee0] .fsl_emb_handle_interrupt+0x20c/0x27c [c00000007c72fd30] [c000000000a2e440] .op_handle_interrupt+0x44/0x58 [c00000007c72fdb0] [c000000000016d68] .performance_monitor_exception+0x74/0x90 [c00000007c72fe30] [c00000000001d8b4] exc_0x260_common+0xfc/0x100 performance_monitor_exception() is executed in a context with interrupt disabled and preemption enabled. When there is a user space page fault happened, do_page_fault() invoke in_atomic() to decide whether kernel should handle such page fault. in_atomic() only check preempt_count. So need call pagefault_disable() to disable preemption before reading user stack. Signed-off-by: Jiang Lu <lu.jiang@windriver.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
130 lines
3 KiB
C
130 lines
3 KiB
C
/**
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* Copyright (C) 2005 Brian Rogan <bcr6@cornell.edu>, IBM
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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**/
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#include <linux/oprofile.h>
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#include <linux/sched.h>
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#include <asm/processor.h>
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#include <linux/uaccess.h>
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#include <asm/compat.h>
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#include <asm/oprofile_impl.h>
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#define STACK_SP(STACK) *(STACK)
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#define STACK_LR64(STACK) *((unsigned long *)(STACK) + 2)
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#define STACK_LR32(STACK) *((unsigned int *)(STACK) + 1)
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#ifdef CONFIG_PPC64
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#define STACK_LR(STACK) STACK_LR64(STACK)
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#else
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#define STACK_LR(STACK) STACK_LR32(STACK)
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#endif
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static unsigned int user_getsp32(unsigned int sp, int is_first)
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{
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unsigned int stack_frame[2];
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void __user *p = compat_ptr(sp);
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if (!access_ok(VERIFY_READ, p, sizeof(stack_frame)))
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return 0;
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/*
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* The most likely reason for this is that we returned -EFAULT,
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* which means that we've done all that we can do from
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* interrupt context.
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*/
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if (__copy_from_user_inatomic(stack_frame, p, sizeof(stack_frame)))
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return 0;
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if (!is_first)
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oprofile_add_trace(STACK_LR32(stack_frame));
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/*
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* We do not enforce increasing stack addresses here because
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* we may transition to a different stack, eg a signal handler.
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*/
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return STACK_SP(stack_frame);
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}
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#ifdef CONFIG_PPC64
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static unsigned long user_getsp64(unsigned long sp, int is_first)
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{
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unsigned long stack_frame[3];
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if (!access_ok(VERIFY_READ, (void __user *)sp, sizeof(stack_frame)))
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return 0;
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if (__copy_from_user_inatomic(stack_frame, (void __user *)sp,
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sizeof(stack_frame)))
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return 0;
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if (!is_first)
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oprofile_add_trace(STACK_LR64(stack_frame));
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return STACK_SP(stack_frame);
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}
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#endif
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static unsigned long kernel_getsp(unsigned long sp, int is_first)
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{
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unsigned long *stack_frame = (unsigned long *)sp;
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if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
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return 0;
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if (!is_first)
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oprofile_add_trace(STACK_LR(stack_frame));
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/*
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* We do not enforce increasing stack addresses here because
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* we might be transitioning from an interrupt stack to a kernel
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* stack. validate_sp() is designed to understand this, so just
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* use it.
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*/
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return STACK_SP(stack_frame);
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}
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void op_powerpc_backtrace(struct pt_regs * const regs, unsigned int depth)
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{
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unsigned long sp = regs->gpr[1];
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int first_frame = 1;
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/* We ditch the top stackframe so need to loop through an extra time */
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depth += 1;
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if (!user_mode(regs)) {
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while (depth--) {
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sp = kernel_getsp(sp, first_frame);
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if (!sp)
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break;
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first_frame = 0;
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}
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} else {
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pagefault_disable();
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#ifdef CONFIG_PPC64
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if (!is_32bit_task()) {
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while (depth--) {
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sp = user_getsp64(sp, first_frame);
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if (!sp)
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break;
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first_frame = 0;
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}
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pagefault_enable();
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return;
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}
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#endif
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while (depth--) {
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sp = user_getsp32(sp, first_frame);
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if (!sp)
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break;
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first_frame = 0;
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}
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pagefault_enable();
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}
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}
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