From 91e92272caefad4b6156572fc41671dcbd93afe5 Mon Sep 17 00:00:00 2001 From: Fangrui Song Date: Fri, 24 Sep 2021 09:36:32 -0700 Subject: [PATCH] i386: Port elf_machine_{load_address,dynamic} from x86-64 This drops reliance on _GLOBAL_OFFSET_TABLE_[0] being the link-time address of _DYNAMIC. The code sequence length does not change. Reviewed-by: H.J. Lu --- sysdeps/i386/dl-machine.h | 27 ++++++++++----------------- 1 file changed, 10 insertions(+), 17 deletions(-) diff --git a/sysdeps/i386/dl-machine.h b/sysdeps/i386/dl-machine.h index 590b41d8d7..0401888508 100644 --- a/sysdeps/i386/dl-machine.h +++ b/sysdeps/i386/dl-machine.h @@ -34,27 +34,20 @@ elf_machine_matches_host (const Elf32_Ehdr *ehdr) } -/* Return the link-time address of _DYNAMIC. Conveniently, this is the - first element of the GOT, a special entry that is never relocated. */ -static inline Elf32_Addr __attribute__ ((unused, const)) -elf_machine_dynamic (void) -{ - /* This produces a GOTOFF reloc that resolves to zero at link time, so in - fact just loads from the GOT register directly. By doing it without - an asm we can let the compiler choose any register. */ - 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)) elf_machine_load_address (void) { - /* Compute the difference between the runtime address of _DYNAMIC as seen - by a GOTOFF reference, and the link-time address found in the special - unrelocated first GOT entry. */ - extern Elf32_Dyn bygotoff[] asm ("_DYNAMIC") attribute_hidden; - return (Elf32_Addr) &bygotoff - elf_machine_dynamic (); + extern const Elf32_Ehdr __ehdr_start attribute_hidden; + return (Elf32_Addr) &__ehdr_start; +} + +/* Return the link-time address of _DYNAMIC. */ +static inline Elf32_Addr __attribute__ ((unused)) +elf_machine_dynamic (void) +{ + extern Elf32_Dyn _DYNAMIC[] attribute_hidden; + return (Elf32_Addr) _DYNAMIC - elf_machine_load_address (); } /* Set up the loaded object described by L so its unrelocated PLT