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csky/ftrace: Fixup ftrace_modify_code deadlock without CPU_HAS_ICACHE_INS

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If ICACHE_INS is not supported, we use IPI to sync icache on each
core. But ftrace_modify_code is called from stop_machine from default
implementation of arch_ftrace_update_code and stop_machine callback
is irq_disabled. When you call ipi with irq_disabled, a deadlock will
happen.

We couldn't use icache_flush with irq_disabled, but startup make_nop
is specific case and it needn't ipi other cores.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
This commit is contained in:
Guo Ren
2020-03-31 22:15:42 +08:00
parent 89a3927a77
commit dd7c983e78
2 changed files with 70 additions and 6 deletions
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31
arch/csky/kernel/ftrace.c
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@@ -3,6 +3,7 @@
#include <linux/ftrace.h>
#include <linux/uaccess.h>
#include <linux/stop_machine.h>
#include <asm/cacheflush.h>
#ifdef CONFIG_DYNAMIC_FTRACE
@@ -201,5 +202,35 @@ int ftrace_disable_ftrace_graph_caller(void)
#endif /* CONFIG_DYNAMIC_FTRACE */
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
#ifndef CONFIG_CPU_HAS_ICACHE_INS
struct ftrace_modify_param {
int command;
atomic_t cpu_count;
};
static int __ftrace_modify_code(void *data)
{
struct ftrace_modify_param *param = data;
if (atomic_inc_return(&param->cpu_count) == 1) {
ftrace_modify_all_code(param->command);
atomic_inc(&param->cpu_count);
} else {
while (atomic_read(&param->cpu_count) <= num_online_cpus())
cpu_relax();
local_icache_inv_all(NULL);
}
return 0;
}
void arch_ftrace_update_code(int command)
{
struct ftrace_modify_param param = { command, ATOMIC_INIT(0) };
stop_machine(__ftrace_modify_code, &param, cpu_online_mask);
}
#endif
/* _mcount is defined in abi's mcount.S */
EXPORT_SYMBOL(_mcount);