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riscv: patch code by fixmap mapping

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On strict kernel memory permission, the ftrace have to change the
permission of text for dynamic patching the intructions. Use
riscv_patch_text_nosync() to patch code instead of probe_kernel_write.

Signed-off-by: Zong Li <zong.li@sifive.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
This commit is contained in:
Zong Li 2020-03-10 00:55:44 +08:00 committed by Palmer Dabbelt
parent 043cb41a85
commit 8fdddb2eae
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1 changed files with 4 additions and 9 deletions
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13
arch/riscv/kernel/ftrace.c
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@ -8,6 +8,7 @@
#include <linux/ftrace.h>
#include <linux/uaccess.h>
#include <asm/cacheflush.h>
#include <asm/patch.h>
#ifdef CONFIG_DYNAMIC_FTRACE
static int ftrace_check_current_call(unsigned long hook_pos,
@ -46,20 +47,14 @@ static int __ftrace_modify_call(unsigned long hook_pos, unsigned long target,
{
unsigned int call[2];
unsigned int nops[2] = {NOP4, NOP4};
int ret = 0;
make_call(hook_pos, target, call);
/* replace the auipc-jalr pair at once */
ret = probe_kernel_write((void *)hook_pos, enable ? call : nops,
MCOUNT_INSN_SIZE);
/* return must be -EPERM on write error */
if (ret)
/* Replace the auipc-jalr pair at once. Return -EPERM on write error. */
if (riscv_patch_text_nosync
((void *)hook_pos, enable ? call : nops, MCOUNT_INSN_SIZE))
return -EPERM;
smp_mb();
flush_icache_range((void *)hook_pos, (void *)hook_pos + MCOUNT_INSN_SIZE);
return 0;
}