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1851b9a46 riscv: fix oops caused by irqsoff latency tracer ... Browse Code »

commit 22e2100b1b07d6f5acc71cc1acb53f680c677d77 upstream.

The trace_hardirqs_{on,off}() require the caller to setup frame pointer
properly. This because these two functions use macro 'CALLER_ADDR1' (aka.
__builtin_return_address(1)) to acquire caller info. If the $fp is used
for other purpose, the code generated this macro (as below) could trigger
memory access fault.

0xffffffff8011510e : ld a1,-16(s0)
0xffffffff80115112 : ld s2,-8(a1) # ] restore_all+0x12/0x6e

This because the $fp(aka. $s0) register is not used as frame pointer in the
assembly entry code.

resume_kernel:
REG_L s0, TASK_TI_PREEMPT_COUNT(tp)
bnez s0, restore_all
REG_L s0, TASK_TI_FLAGS(tp)
andi s0, s0, _TIF_NEED_RESCHED
beqz s0, restore_all
call preempt_schedule_irq
j restore_all

To fix above issue, here we add one extra level wrapper for function
trace_hardirqs_{on,off}() so they can be safely called by low level entry
code.

Signed-off-by: Changbin Du
Fixes: 3c4697982982 ("riscv: Enable LOCKDEP_SUPPORT & fixup TRACE_IRQFLAGS_SUPPORT")
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt
Signed-off-by: Greg Kroah-Hartman

Changbin Du
2022-03-02 18:48:08 +0800

trace_irq.h 242 Bytes

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/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Copyright (C) 2022 Changbin Du <changbin.du@gmail.com>
 */
#ifndef __TRACE_IRQ_H
#define __TRACE_IRQ_H

void __trace_hardirqs_on(void);
void __trace_hardirqs_off(void);

#endif /* __TRACE_IRQ_H */