56 lines
2.0 KiB
Diff
56 lines
2.0 KiB
Diff
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From b37b75d269883a2c553bb7019a813094eb4e2dd1 Mon Sep 17 00:00:00 2001
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From: Fangrui Song <maskray@google.com>
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Date: Tue, 17 Aug 2021 10:45:57 -0700
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Subject: [PATCH] x86_64: Simplify elf_machine_{load_address,dynamic}
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and drop reliance on _GLOBAL_OFFSET_TABLE_[0] being the link-time
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address of _DYNAMIC. &__ehdr_start is a better way to get the load address.
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Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
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---
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sysdeps/x86_64/dl-machine.h | 21 +++++++--------------
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1 file changed, 7 insertions(+), 14 deletions(-)
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diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h
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index a8596aa..ceee507 100644
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--- a/sysdeps/x86_64/dl-machine.h
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+++ b/sysdeps/x86_64/dl-machine.h
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@@ -35,27 +35,20 @@ elf_machine_matches_host (const ElfW(Ehdr) *ehdr)
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}
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-/* Return the link-time address of _DYNAMIC. Conveniently, this is the
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- first element of the GOT. This must be inlined in a function which
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- uses global data. */
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+/* Return the run-time load address of the shared object. */
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static inline ElfW(Addr) __attribute__ ((unused))
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-elf_machine_dynamic (void)
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+elf_machine_load_address (void)
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{
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- /* This produces an IP-relative reloc which is resolved at link time. */
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- extern const ElfW(Addr) _GLOBAL_OFFSET_TABLE_[] attribute_hidden;
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- return _GLOBAL_OFFSET_TABLE_[0];
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+ extern const ElfW(Ehdr) __ehdr_start attribute_hidden;
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+ return (ElfW(Addr)) &__ehdr_start;
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}
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-
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-/* Return the run-time load address of the shared object. */
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+/* Return the link-time address of _DYNAMIC. */
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static inline ElfW(Addr) __attribute__ ((unused))
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-elf_machine_load_address (void)
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+elf_machine_dynamic (void)
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{
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- /* Compute the difference between the runtime address of _DYNAMIC as seen
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- by an IP-relative reference, and the link-time address found in the
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- special unrelocated first GOT entry. */
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extern ElfW(Dyn) _DYNAMIC[] attribute_hidden;
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- return (ElfW(Addr)) &_DYNAMIC - elf_machine_dynamic ();
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+ return (ElfW(Addr)) _DYNAMIC - elf_machine_load_address ();
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}
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/* Set up the loaded object described by L so its unrelocated PLT
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--
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1.8.3.1
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