diff options
Diffstat (limited to 'arm-Simplify-elf_machine_-load_address-dynamic.patch')
| -rw-r--r-- | arm-Simplify-elf_machine_-load_address-dynamic.patch | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/arm-Simplify-elf_machine_-load_address-dynamic.patch b/arm-Simplify-elf_machine_-load_address-dynamic.patch new file mode 100644 index 0000000..42987ce --- /dev/null +++ b/arm-Simplify-elf_machine_-load_address-dynamic.patch @@ -0,0 +1,82 @@ +From bca0f5cbc9257c13322b99e55235c4f21ba0bd82 Mon Sep 17 00:00:00 2001 +From: Fangrui Song <maskray@google.com> +Date: Wed, 18 Aug 2021 11:13:03 -0700 +Subject: [PATCH] arm: Simplify elf_machine_{load_address,dynamic} + +and drop reliance on _GLOBAL_OFFSET_TABLE_[0] being the link-time +address of _DYNAMIC. &__ehdr_start is a better way to get the load address. + +This is similar to commits b37b75d269883a2c553bb7019a813094eb4e2dd1 +(x86-64) and 43d06ed218fc8be58987bdfd00e21e5720f0b862 (aarch64). + +Reviewed-by: Joseph Myers <joseph@codesourcery.com> +--- + sysdeps/arm/dl-machine.h | 47 ++++++++++------------------------------------- + 1 file changed, 10 insertions(+), 37 deletions(-) + +diff --git a/sysdeps/arm/dl-machine.h b/sysdeps/arm/dl-machine.h +index ff5e09e..eb13cb8 100644 +--- a/sysdeps/arm/dl-machine.h ++++ b/sysdeps/arm/dl-machine.h +@@ -37,48 +37,21 @@ elf_machine_matches_host (const Elf32_Ehdr *ehdr) + return ehdr->e_machine == EM_ARM; + } + +- +-/* Return the link-time address of _DYNAMIC. Conveniently, this is the +- first element of the GOT. */ +-static inline Elf32_Addr __attribute__ ((unused)) +-elf_machine_dynamic (void) +-{ +- /* Declaring this hidden ensures that a PC-relative reference is used. */ +- extern const Elf32_Addr _GLOBAL_OFFSET_TABLE_[] attribute_hidden; +- return _GLOBAL_OFFSET_TABLE_[0]; +-} +- +- + /* Return the run-time load address of the shared object. */ +-static inline Elf32_Addr __attribute__ ((unused)) ++static inline ElfW(Addr) __attribute__ ((unused)) + elf_machine_load_address (void) + { +- Elf32_Addr pcrel_addr; +-#ifdef SHARED +- extern Elf32_Addr __dl_start (void *) asm ("_dl_start"); +- Elf32_Addr got_addr = (Elf32_Addr) &__dl_start; +- asm ("adr %0, _dl_start" : "=r" (pcrel_addr)); +-#else +- extern Elf32_Addr __dl_relocate_static_pie (void *) +- asm ("_dl_relocate_static_pie") attribute_hidden; +- Elf32_Addr got_addr = (Elf32_Addr) &__dl_relocate_static_pie; +- asm ("adr %0, _dl_relocate_static_pie" : "=r" (pcrel_addr)); +-#endif +-#ifdef __thumb__ +- /* Clear the low bit of the function address. +- +- NOTE: got_addr is from GOT table whose lsb is always set by linker if it's +- Thumb function address. PCREL_ADDR comes from PC-relative calculation +- which will finish during assembling. GAS assembler before the fix for +- PR gas/21458 was not setting the lsb but does after that. Always do the +- strip for both, so the code works with various combinations of glibc and +- Binutils. */ +- got_addr &= ~(Elf32_Addr) 1; +- pcrel_addr &= ~(Elf32_Addr) 1; +-#endif +- return pcrel_addr - got_addr; ++ extern const ElfW(Ehdr) __ehdr_start attribute_hidden; ++ return (ElfW(Addr)) &__ehdr_start; + } + ++/* Return the link-time address of _DYNAMIC. */ ++static inline ElfW(Addr) __attribute__ ((unused)) ++elf_machine_dynamic (void) ++{ ++ extern ElfW(Dyn) _DYNAMIC[] attribute_hidden; ++ return (ElfW(Addr)) _DYNAMIC - elf_machine_load_address (); ++} + + /* Set up the loaded object described by L so its unrelocated PLT + entries will jump to the on-demand fixup code in dl-runtime.c. */ +-- +1.8.3.1 + |