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Commit 2e1926e7 authored by Catalin Marinas's avatar Catalin Marinas Committed by Russell King
Browse files

[ARM] 5384/1: unwind: Add stack unwinding support for loadable modules 



This patch adds ELF section parsing for the unwinding tables in loadable
modules together with the PREL31 relocation symbol resolving.

Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent bff595c1

arch/arm/include/asm/elf.h

+1 −0
Original line number Diff line number Diff line
@@ -50,6 +50,7 @@ typedef struct user_fp elf_fpregset_t; 
#define R_ARM_ABS32	2

#define R_ARM_CALL	28

#define R_ARM_JUMP24	29

#define R_ARM_PREL31	42



/*

 * These are used to set parameters in the core dumps.

arch/arm/include/asm/module.h

+17 −5
Original line number Diff line number Diff line 
#ifndef _ASM_ARM_MODULE_H

#define _ASM_ARM_MODULE_H



struct mod_arch_specific

{

	int foo;

};



#define Elf_Shdr	Elf32_Shdr

#define Elf_Sym		Elf32_Sym

#define Elf_Ehdr	Elf32_Ehdr



struct unwind_table;



struct mod_arch_specific

{

#ifdef CONFIG_ARM_UNWIND

	Elf_Shdr *unw_sec_init;

	Elf_Shdr *unw_sec_devinit;

	Elf_Shdr *unw_sec_core;

	Elf_Shdr *sec_init_text;

	Elf_Shdr *sec_devinit_text;

	Elf_Shdr *sec_core_text;

	struct unwind_table *unwind_init;

	struct unwind_table *unwind_devinit;

	struct unwind_table *unwind_core;

#endif

};



/*

 * Include the ARM architecture version.

 */

arch/arm/kernel/module.c

+64 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 


#include <asm/pgtable.h>

#include <asm/sections.h>

#include <asm/unwind.h>



#ifdef CONFIG_XIP_KERNEL

/*
@@ -66,6 +67,24 @@ int module_frob_arch_sections(Elf_Ehdr *hdr, 
			      char *secstrings,

			      struct module *mod)

{

#ifdef CONFIG_ARM_UNWIND

	Elf_Shdr *s, *sechdrs_end = sechdrs + hdr->e_shnum;



	for (s = sechdrs; s < sechdrs_end; s++) {

		if (strcmp(".ARM.exidx.init.text", secstrings + s->sh_name) == 0)

			mod->arch.unw_sec_init = s;

		else if (strcmp(".ARM.exidx.devinit.text", secstrings + s->sh_name) == 0)

			mod->arch.unw_sec_devinit = s;

		else if (strcmp(".ARM.exidx", secstrings + s->sh_name) == 0)

			mod->arch.unw_sec_core = s;

		else if (strcmp(".init.text", secstrings + s->sh_name) == 0)

			mod->arch.sec_init_text = s;

		else if (strcmp(".devinit.text", secstrings + s->sh_name) == 0)

			mod->arch.sec_devinit_text = s;

		else if (strcmp(".text", secstrings + s->sh_name) == 0)

			mod->arch.sec_core_text = s;

	}

#endif

	return 0;

}
@@ -104,6 +123,10 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex, 
		loc = dstsec->sh_addr + rel->r_offset;



		switch (ELF32_R_TYPE(rel->r_info)) {

		case R_ARM_NONE:

			/* ignore */

			break;



		case R_ARM_ABS32:

			*(u32 *)loc += sym->st_value;

			break;
@@ -132,6 +155,11 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex, 
			*(u32 *)loc |= offset & 0x00ffffff;

			break;



		case R_ARM_PREL31:

			offset = *(u32 *)loc + sym->st_value - loc;

			*(u32 *)loc = offset & 0x7fffffff;

			break;



		default:

			printk(KERN_ERR "%s: unknown relocation: %u\n",

			       module->name, ELF32_R_TYPE(rel->r_info));
@@ -150,14 +178,50 @@ apply_relocate_add(Elf32_Shdr *sechdrs, const char *strtab, 
	return -ENOEXEC;

}



#ifdef CONFIG_ARM_UNWIND

static void register_unwind_tables(struct module *mod)

{

	if (mod->arch.unw_sec_init && mod->arch.sec_init_text)

		mod->arch.unwind_init =

			unwind_table_add(mod->arch.unw_sec_init->sh_addr,

					 mod->arch.unw_sec_init->sh_size,

					 mod->arch.sec_init_text->sh_addr,

					 mod->arch.sec_init_text->sh_size);

	if (mod->arch.unw_sec_devinit && mod->arch.sec_devinit_text)

		mod->arch.unwind_devinit =

			unwind_table_add(mod->arch.unw_sec_devinit->sh_addr,

					 mod->arch.unw_sec_devinit->sh_size,

					 mod->arch.sec_devinit_text->sh_addr,

					 mod->arch.sec_devinit_text->sh_size);

	if (mod->arch.unw_sec_core && mod->arch.sec_core_text)

		mod->arch.unwind_core =

			unwind_table_add(mod->arch.unw_sec_core->sh_addr,

					 mod->arch.unw_sec_core->sh_size,

					 mod->arch.sec_core_text->sh_addr,

					 mod->arch.sec_core_text->sh_size);

}



static void unregister_unwind_tables(struct module *mod)

{

	unwind_table_del(mod->arch.unwind_init);

	unwind_table_del(mod->arch.unwind_devinit);

	unwind_table_del(mod->arch.unwind_core);

}

#else

static inline void register_unwind_tables(struct module *mod) { }

static inline void unregister_unwind_tables(struct module *mod) { }

#endif



int

module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,

		struct module *module)

{

	register_unwind_tables(module);

	return 0;

}



void

module_arch_cleanup(struct module *mod)

{

	unregister_unwind_tables(mod);

}