From: Fangrui Song <maskray@google.com>
Date: Wed, 18 Aug 2021 17:01:31 +0000 (-0700)
Subject: riscv: Drop reliance on _GLOBAL_OFFSET_TABLE_[0]
X-Git-Tag: glibc-2.35~574
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=34b4624b04fc8f038b2c329ca7560197320615b4;p=thirdparty%2Fglibc.git

riscv: Drop reliance on _GLOBAL_OFFSET_TABLE_[0]

&__ehdr_start is a better way to get the load address.

This is similar to commits b37b75d269883a2c553bb7019a813094eb4e2dd1
(x86-64) and 43d06ed218fc8be58987bdfd00e21e5720f0b862 (aarch64).

Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
---

diff --git a/sysdeps/riscv/dl-machine.h b/sysdeps/riscv/dl-machine.h
index aedf69fcdd8..5b0746175cf 100644
--- a/sysdeps/riscv/dl-machine.h
+++ b/sysdeps/riscv/dl-machine.h
@@ -76,27 +76,26 @@ elf_machine_matches_host (const ElfW(Ehdr) *ehdr)
   return 1;
 }
 
+/* Return the run-time load address of the shared object.  */
+static inline ElfW(Addr)
+elf_machine_load_address (void)
+{
+  extern const ElfW(Ehdr) __ehdr_start attribute_hidden;
+  return (ElfW(Addr)) &__ehdr_start;
+}
+
 /* Return the link-time address of _DYNAMIC.  */
 static inline ElfW(Addr)
 elf_machine_dynamic (void)
 {
-  extern ElfW(Addr) _GLOBAL_OFFSET_TABLE_ __attribute__ ((visibility ("hidden")));
-  return _GLOBAL_OFFSET_TABLE_;
+  extern ElfW(Dyn) _DYNAMIC[] attribute_hidden;
+  return (ElfW(Addr)) _DYNAMIC - elf_machine_load_address ();
 }
 
 #define STRINGXP(X) __STRING (X)
 #define STRINGXV(X) STRINGV_ (X)
 #define STRINGV_(...) # __VA_ARGS__
 
-/* Return the run-time load address of the shared object.  */
-static inline ElfW(Addr)
-elf_machine_load_address (void)
-{
-  ElfW(Addr) load_addr;
-  asm ("lla %0, _DYNAMIC" : "=r" (load_addr));
-  return load_addr - elf_machine_dynamic ();
-}
-
 /* Initial entry point code for the dynamic linker.
    The C function `_dl_start' is the real entry point;
    its return value is the user program's entry point.  */