Messages in this thread Patch in this message | | | From | Zong Li <> | Subject | [PATCH v4 3/9] riscv: patch code by fixmap mapping | Date | Tue, 7 Apr 2020 22:46:48 +0800 |
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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> Suggested-by: Masami Hiramatsu <mhiramat@kernel.org> --- arch/riscv/kernel/ftrace.c | 26 +++++++++++++++++--------- 1 file changed, 17 insertions(+), 9 deletions(-)
diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c index c40fdcdeb950..08396614d6f4 100644 --- a/arch/riscv/kernel/ftrace.c +++ b/arch/riscv/kernel/ftrace.c @@ -7,9 +7,23 @@ #include <linux/ftrace.h> #include <linux/uaccess.h> +#include <linux/memory.h> #include <asm/cacheflush.h> +#include <asm/patch.h> #ifdef CONFIG_DYNAMIC_FTRACE +int ftrace_arch_code_modify_prepare(void) __acquires(&text_mutex) +{ + mutex_lock(&text_mutex); + return 0; +} + +int ftrace_arch_code_modify_post_process(void) __releases(&text_mutex) +{ + mutex_unlock(&text_mutex); + return 0; +} + static int ftrace_check_current_call(unsigned long hook_pos, unsigned int *expected) { @@ -46,20 +60,14 @@ 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 (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; } -- 2.26.0
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