[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: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/include/asm/elf.h b/arch/arm/include/asm/elf.h
index a58378c..def8eac 100644
--- a/arch/arm/include/asm/elf.h
+++ b/arch/arm/include/asm/elf.h
@@ -50,6 +50,7 @@
#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.
diff --git a/arch/arm/include/asm/module.h b/arch/arm/include/asm/module.h
index 24b168d..e4dfa69 100644
--- a/arch/arm/include/asm/module.h
+++ b/arch/arm/include/asm/module.h
@@ -1,15 +1,27 @@
#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.
*/
diff --git a/arch/arm/kernel/module.c b/arch/arm/kernel/module.c
index dab48f2..13dbd5b 100644
--- a/arch/arm/kernel/module.c
+++ b/arch/arm/kernel/module.c
@@ -22,6 +22,7 @@
#include <asm/pgtable.h>
#include <asm/sections.h>
+#include <asm/unwind.h>
#ifdef CONFIG_XIP_KERNEL
/*
@@ -66,6 +67,24 @@
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 @@
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 @@
*(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 @@
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);
}