Unverified Commit 8fdddb2e authored by Zong Li's avatar Zong Li Committed by Palmer Dabbelt
Browse files

riscv: patch code by fixmap mapping 



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: default avatarZong Li <zong.li@sifive.com>
Signed-off-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
parent 043cb41a

arch/riscv/kernel/ftrace.c

+4 −9
Original line number Diff line number Diff line
@@ -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;

}

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