ftrace/recordmcount: Avoid STT_FUNC symbols as base on ARM (9905ce8a) · Commits · 戴 / test

While find_secsym_ndx often finds the unamed local STT_SECTION, if a section has only one function in it, the ARM toolchain generates the STT_FUNC symbol before the STT_SECTION, and recordmcount finds this instead. This is problematic on ARM because in ARM ELFs, "if a [STT_FUNC] symbol addresses a Thumb instruction, its value is the address of the instruction with bit zero set (in a relocatable object, the section offset with bit zero set)". This leads to incorrect mcount addresses being recorded. Fix this by not using STT_FUNC symbols as the base on ARM. Signed-off-by:

Rabin Vincent <rabin@rab.in> Link: http://lkml.kernel.org/r/1305134631-31617-1-git-send-email-rabin@rab.in Signed-off-by:

Steven Rostedt <rostedt@goodmis.org>

scripts/recordmcount.h

+8 −0

Original line number	Diff line number	Diff line
		@@ -43,6 +43,7 @@
		#undef ELF_R_INFO
		#undef Elf_r_info
		#undef ELF_ST_BIND
		#undef ELF_ST_TYPE
		#undef fn_ELF_R_SYM
		#undef fn_ELF_R_INFO
		#undef uint_t
		@@ -76,6 +77,7 @@
		# define ELF_R_INFO ELF64_R_INFO
		# define Elf_r_info Elf64_r_info
		# define ELF_ST_BIND ELF64_ST_BIND
		# define ELF_ST_TYPE ELF64_ST_TYPE
		# define fn_ELF_R_SYM fn_ELF64_R_SYM
		# define fn_ELF_R_INFO fn_ELF64_R_INFO
		# define uint_t uint64_t
		@@ -108,6 +110,7 @@
		# define ELF_R_INFO ELF32_R_INFO
		# define Elf_r_info Elf32_r_info
		# define ELF_ST_BIND ELF32_ST_BIND
		# define ELF_ST_TYPE ELF32_ST_TYPE
		# define fn_ELF_R_SYM fn_ELF32_R_SYM
		# define fn_ELF_R_INFO fn_ELF32_R_INFO
		# define uint_t uint32_t
		@@ -427,6 +430,11 @@ static unsigned find_secsym_ndx(unsigned const txtndx,
		if (txtndx == w2(symp->st_shndx)
		/* avoid STB_WEAK */
		&& (STB_LOCAL == st_bind \|\| STB_GLOBAL == st_bind)) {
		/* function symbols on ARM have quirks, avoid them */
		if (w2(ehdr->e_machine) == EM_ARM
		&& ELF_ST_TYPE(symp->st_info) == STT_FUNC)
		continue;

		*recvalp = _w(symp->st_value);
		return symp - sym0;
		}

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