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csky/ftrace: Fixup ftrace_modify_code deadlock without CPU_HAS_ICACHE_INS 

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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
arch/csky/kernel/ftrace.c
View File

@ -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);

45
arch/csky/mm/cachev2.c
View File

@ -7,8 +7,12 @@
#include <asm/cache.h>
#include <asm/barrier.h>
/* for L1-cache */
#define INS_CACHE (1 << 0)
#define DATA_CACHE (1 << 1)
#define CACHE_INV (1 << 4)
#define CACHE_CLR (1 << 5)
#define CACHE_OMS (1 << 6)
void local_icache_inv_all(void *priv)
{
@ -16,11 +20,6 @@ void local_icache_inv_all(void *priv)
sync_is();
}
void icache_inv_all(void)
{
on_each_cpu(local_icache_inv_all, NULL, 1);
}
#ifdef CONFIG_CPU_HAS_ICACHE_INS
void icache_inv_range(unsigned long start, unsigned long end)
{
@ -31,9 +30,43 @@ void icache_inv_range(unsigned long start, unsigned long end)
sync_is();
}
#else
struct cache_range {
unsigned long start;
unsigned long end;
};
static DEFINE_SPINLOCK(cache_lock);
static inline void cache_op_line(unsigned long i, unsigned int val)
{
mtcr("cr22", i);
mtcr("cr17", val);
}
void local_icache_inv_range(void *priv)
{
struct cache_range *param = priv;
unsigned long i = param->start & ~(L1_CACHE_BYTES - 1);
unsigned long flags;
spin_lock_irqsave(&cache_lock, flags);
for (; i < param->end; i += L1_CACHE_BYTES)
cache_op_line(i, INS_CACHE | CACHE_INV | CACHE_OMS);
spin_unlock_irqrestore(&cache_lock, flags);
sync_is();
}
void icache_inv_range(unsigned long start, unsigned long end)
{
icache_inv_all();
struct cache_range param = { start, end };
if (irqs_disabled())
local_icache_inv_range(&param);
else
on_each_cpu(local_icache_inv_range, &param, 1);
}
#endif