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