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ee69d4be8f
These patch_text implementations are using stop_machine_cpuslocked
infrastructure with atomic cpu_count. The original idea: When the
master CPU patch_text, the others should wait for it. But current
implementation is using the first CPU as master, which couldn't
guarantee the remaining CPUs are waiting. This patch changes the
last CPU as the master to solve the potential risk.
Fixes: 64711f9a47 ("xtensa: implement jump_label support")
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Max Filippov <jcmvbkbc@gmail.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: <stable@vger.kernel.org>
Message-Id: <20220407073323.743224-4-guoren@kernel.org>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
96 lines
2.2 KiB
C
96 lines
2.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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// Copyright (C) 2018 Cadence Design Systems Inc.
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#include <linux/cpu.h>
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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/stop_machine.h>
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#include <linux/types.h>
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#include <asm/cacheflush.h>
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#define J_OFFSET_MASK 0x0003ffff
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#define J_SIGN_MASK (~(J_OFFSET_MASK >> 1))
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#if defined(__XTENSA_EL__)
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#define J_INSN 0x6
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#define NOP_INSN 0x0020f0
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#elif defined(__XTENSA_EB__)
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#define J_INSN 0x60000000
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#define NOP_INSN 0x0f020000
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#else
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#error Unsupported endianness.
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#endif
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struct patch {
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atomic_t cpu_count;
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unsigned long addr;
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size_t sz;
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const void *data;
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};
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static void local_patch_text(unsigned long addr, const void *data, size_t sz)
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{
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memcpy((void *)addr, data, sz);
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local_flush_icache_range(addr, addr + sz);
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}
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static int patch_text_stop_machine(void *data)
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{
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struct patch *patch = data;
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if (atomic_inc_return(&patch->cpu_count) == num_online_cpus()) {
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local_patch_text(patch->addr, patch->data, patch->sz);
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atomic_inc(&patch->cpu_count);
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} else {
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while (atomic_read(&patch->cpu_count) <= num_online_cpus())
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cpu_relax();
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__invalidate_icache_range(patch->addr, patch->sz);
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}
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return 0;
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}
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static void patch_text(unsigned long addr, const void *data, size_t sz)
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{
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if (IS_ENABLED(CONFIG_SMP)) {
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struct patch patch = {
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.cpu_count = ATOMIC_INIT(0),
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.addr = addr,
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.sz = sz,
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.data = data,
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};
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stop_machine_cpuslocked(patch_text_stop_machine,
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&patch, cpu_online_mask);
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} else {
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unsigned long flags;
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local_irq_save(flags);
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local_patch_text(addr, data, sz);
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local_irq_restore(flags);
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}
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}
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void arch_jump_label_transform(struct jump_entry *e,
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enum jump_label_type type)
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{
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u32 d = (jump_entry_target(e) - (jump_entry_code(e) + 4));
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u32 insn;
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/* Jump only works within 128K of the J instruction. */
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BUG_ON(!((d & J_SIGN_MASK) == 0 ||
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(d & J_SIGN_MASK) == J_SIGN_MASK));
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if (type == JUMP_LABEL_JMP) {
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#if defined(__XTENSA_EL__)
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insn = ((d & J_OFFSET_MASK) << 6) | J_INSN;
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#elif defined(__XTENSA_EB__)
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insn = ((d & J_OFFSET_MASK) << 8) | J_INSN;
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#endif
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} else {
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insn = NOP_INSN;
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}
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patch_text(jump_entry_code(e), &insn, JUMP_LABEL_NOP_SIZE);
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}
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