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b3134b8c1a
When CONFIG_DEBUG_RT_MUTEXES=y, mutex_lock->rt_mutex_try_acquire
would change from rt_mutex_cmpxchg_acquire to
rt_mutex_slowtrylock():
raw_spin_lock_irqsave(&lock->wait_lock, flags);
ret = __rt_mutex_slowtrylock(lock);
raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
Because queued_spin_#ops to ticket_#ops is changed one by one by
jump_label, raw_spin_lock/unlock would cause a deadlock during the
changing.
That means in arch/riscv/kernel/jump_label.c:
1.
arch_jump_label_transform_queue() ->
mutex_lock(&text_mutex); +-> raw_spin_lock -> queued_spin_lock
|-> raw_spin_unlock -> queued_spin_unlock
patch_insn_write -> change the raw_spin_lock to ticket_lock
mutex_unlock(&text_mutex);
...
2. /* Dirty the lock value */
arch_jump_label_transform_queue() ->
mutex_lock(&text_mutex); +-> raw_spin_lock -> *ticket_lock*
|-> raw_spin_unlock -> *queued_spin_unlock*
/* BUG: ticket_lock with queued_spin_unlock */
patch_insn_write -> change the raw_spin_unlock to ticket_unlock
mutex_unlock(&text_mutex);
...
3. /* Dead lock */
arch_jump_label_transform_queue() ->
mutex_lock(&text_mutex); +-> raw_spin_lock -> ticket_lock /* deadlock! */
|-> raw_spin_unlock -> ticket_unlock
patch_insn_write -> change other raw_spin_#op -> ticket_#op
mutex_unlock(&text_mutex);
So, the solution is to disable mutex usage of
arch_jump_label_transform_queue() during early_boot_irqs_disabled, just
like we have done for stop_machine.
Reported-by: Conor Dooley <conor@kernel.org>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Fixes: ab83647fad ("riscv: Add qspinlock support")
Link: https://lore.kernel.org/linux-riscv/CAJF2gTQwYTGinBmCSgVUoPv0_q4EPt_+WiyfUA1HViAKgUzxAg@mail.gmail.com/T/#mf488e6347817fca03bb93a7d34df33d8615b3775
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Tested-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Tested-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Tested-by: Nam Cao <namcao@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20241130153310.3349484-1-guoren@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
55 lines
1.3 KiB
C
55 lines
1.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2020 Emil Renner Berthing
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*
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* Based on arch/arm64/kernel/jump_label.c
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*/
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#include <linux/jump_label.h>
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#include <linux/kernel.h>
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#include <linux/memory.h>
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#include <linux/mutex.h>
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#include <asm/bug.h>
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#include <asm/cacheflush.h>
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#include <asm/text-patching.h>
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#define RISCV_INSN_NOP 0x00000013U
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#define RISCV_INSN_JAL 0x0000006fU
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bool arch_jump_label_transform_queue(struct jump_entry *entry,
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enum jump_label_type type)
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{
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void *addr = (void *)jump_entry_code(entry);
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u32 insn;
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if (type == JUMP_LABEL_JMP) {
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long offset = jump_entry_target(entry) - jump_entry_code(entry);
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if (WARN_ON(offset & 1 || offset < -524288 || offset >= 524288))
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return true;
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insn = RISCV_INSN_JAL |
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(((u32)offset & GENMASK(19, 12)) << (12 - 12)) |
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(((u32)offset & GENMASK(11, 11)) << (20 - 11)) |
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(((u32)offset & GENMASK(10, 1)) << (21 - 1)) |
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(((u32)offset & GENMASK(20, 20)) << (31 - 20));
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} else {
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insn = RISCV_INSN_NOP;
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}
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if (early_boot_irqs_disabled) {
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riscv_patch_in_stop_machine = 1;
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patch_insn_write(addr, &insn, sizeof(insn));
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riscv_patch_in_stop_machine = 0;
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} else {
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mutex_lock(&text_mutex);
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patch_insn_write(addr, &insn, sizeof(insn));
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mutex_unlock(&text_mutex);
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}
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return true;
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}
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void arch_jump_label_transform_apply(void)
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{
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flush_icache_all();
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}
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