From b37b75d269883a2c553bb7019a813094eb4e2dd1 Mon Sep 17 00:00:00 2001 From: Fangrui Song Date: Tue, 17 Aug 2021 10:45:57 -0700 Subject: [PATCH] x86_64: 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. Reviewed-by: H.J. Lu --- sysdeps/x86_64/dl-machine.h | 25 +++++++++---------------- 1 file changed, 9 insertions(+), 16 deletions(-) diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h index a8596aa3fa..ceee50734e 100644 --- a/sysdeps/x86_64/dl-machine.h +++ b/sysdeps/x86_64/dl-machine.h @@ -35,27 +35,20 @@ elf_machine_matches_host (const ElfW(Ehdr) *ehdr) } -/* Return the link-time address of _DYNAMIC. Conveniently, this is the - first element of the GOT. This must be inlined in a function which - uses global data. */ -static inline ElfW(Addr) __attribute__ ((unused)) -elf_machine_dynamic (void) -{ - /* This produces an IP-relative reloc which is resolved at link time. */ - extern const ElfW(Addr) _GLOBAL_OFFSET_TABLE_[] attribute_hidden; - return _GLOBAL_OFFSET_TABLE_[0]; -} - - /* Return the run-time load address of the shared object. */ static inline ElfW(Addr) __attribute__ ((unused)) elf_machine_load_address (void) { - /* Compute the difference between the runtime address of _DYNAMIC as seen - by an IP-relative reference, and the link-time address found in the - special unrelocated first GOT entry. */ + 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_dynamic (); + return (ElfW(Addr)) _DYNAMIC - elf_machine_load_address (); } /* Set up the loaded object described by L so its unrelocated PLT