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csky: patch_text: Fixup last cpu should be master

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commit 8c4d16471e upstream.

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: 33e53ae1ce ("csky: Add kprobes supported")
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Guo Ren 2022-04-06 22:28:43 +08:00 • committed by Justin Hammond
parent 008990a9ac
commit 86569e607d
1 changed files with 1 additions and 1 deletions
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2
arch/csky/kernel/probes/kprobes.c
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@ -28,7 +28,7 @@ static int __kprobes patch_text_cb(void *priv)
struct csky_insn_patch *param = priv;
unsigned int addr = (unsigned int)param->addr;
if (atomic_inc_return(&param->cpu_count) == 1) {
if (atomic_inc_return(&param->cpu_count) == num_online_cpus()) {
*(u16 *) addr = cpu_to_le16(param->opcode);
dcache_wb_range(addr, addr + 2);
atomic_inc(&param->cpu_count);