x86_64, ftrace: Make ftrace use kernel identity mapping to modify code (55ca3cc1) · Commits · 戴 / test

arch/x86/kernel/ftrace.c

+17 −0

Original line number	Diff line number	Diff line
		@@ -187,9 +187,26 @@ static void wait_for_nmi(void)
		nmi_wait_count++;
		}

		static inline int
		within(unsigned long addr, unsigned long start, unsigned long end)
		{
		return addr >= start && addr < end;
		}

		static int
		do_ftrace_mod_code(unsigned long ip, void *new_code)
		{
		/*
		* On x86_64, kernel text mappings are mapped read-only with
		* CONFIG_DEBUG_RODATA. So we use the kernel identity mapping instead
		* of the kernel text mapping to modify the kernel text.
		*
		* For 32bit kernels, these mappings are same and we can use
		* kernel identity mapping to modify code.
		*/
		if (within(ip, (unsigned long)_text, (unsigned long)_etext))
		ip = (unsigned long)__va(__pa(ip));

		mod_code_ip = (void *)ip;
		mod_code_newcode = new_code;

+1 −2

Original line number	Diff line number	Diff line
		@@ -279,8 +279,7 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
		__pa((unsigned long)__end_rodata) >> PAGE_SHIFT))
		pgprot_val(forbidden) \|= _PAGE_RW;

		#if defined(CONFIG_X86_64) && defined(CONFIG_DEBUG_RODATA) && \
		!defined(CONFIG_DYNAMIC_FTRACE)
		#if defined(CONFIG_X86_64) && defined(CONFIG_DEBUG_RODATA)
		/*
		* Once the kernel maps the text as RO (kernel_set_to_readonly is set),
		* kernel text mappings for the large page aligned text, rodata sections