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* [glibc/release/2.38/master] powerpc: Fix ld.so address determination for PCREL mode (bug 31640)
@ 2024-04-14 7:10 Florian Weimer
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From: Florian Weimer @ 2024-04-14 7:10 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=20534f81760635f3a71fb11ba251568cdc11c6a0
commit 20534f81760635f3a71fb11ba251568cdc11c6a0
Author: Florian Weimer <fweimer@redhat.com>
Date: Sun Apr 14 08:24:51 2024 +0200
powerpc: Fix ld.so address determination for PCREL mode (bug 31640)
This seems to have stopped working with some GCC 14 versions,
which clobber r2. With other compilers, the kernel-provided
r2 value is still available at this point.
Reviewed-by: Peter Bergner <bergner@linux.ibm.com>
(cherry picked from commit 14e56bd4ce15ac2d1cc43f762eb2e6b83fec1afe)
Diff:
---
sysdeps/powerpc/powerpc64/dl-machine.h | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/sysdeps/powerpc/powerpc64/dl-machine.h b/sysdeps/powerpc/powerpc64/dl-machine.h
index 9b8943bc91..7fa8a355b5 100644
--- a/sysdeps/powerpc/powerpc64/dl-machine.h
+++ b/sysdeps/powerpc/powerpc64/dl-machine.h
@@ -79,6 +79,7 @@ elf_host_tolerates_class (const Elf64_Ehdr *ehdr)
static inline Elf64_Addr
elf_machine_load_address (void) __attribute__ ((const));
+#ifndef __PCREL__
static inline Elf64_Addr
elf_machine_load_address (void)
{
@@ -106,6 +107,24 @@ elf_machine_dynamic (void)
/* Then subtract off the load address offset. */
return runtime_dynamic - elf_machine_load_address() ;
}
+#else /* __PCREL__ */
+/* In PCREL mode, r2 may have been clobbered. Rely on relative
+ relocations instead. */
+
+static inline ElfW(Addr)
+elf_machine_load_address (void)
+{
+ extern const ElfW(Ehdr) __ehdr_start attribute_hidden;
+ return (ElfW(Addr)) &__ehdr_start;
+}
+
+static inline ElfW(Addr)
+elf_machine_dynamic (void)
+{
+ extern ElfW(Dyn) _DYNAMIC[] attribute_hidden;
+ return (ElfW(Addr)) _DYNAMIC - elf_machine_load_address ();
+}
+#endif /* __PCREL__ */
/* The PLT uses Elf64_Rela relocs. */
#define elf_machine_relplt elf_machine_rela
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2024-04-14 7:10 [glibc/release/2.38/master] powerpc: Fix ld.so address determination for PCREL mode (bug 31640) Florian Weimer
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