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| author | Samuel Holland <samuel@sholland.org> | 2019-06-30 07:39:20 -0500 |
|---|---|---|
| committer | Rich Felker <dalias@aerifal.cx> | 2019-08-11 17:43:57 -0400 |
| commit | 08869deb7efbda6e979886cb67e3d5843f92c2e8 (patch) | |
| tree | 93547135ee0d59dd87831e8728f9c154e3d8e79e | |
| parent | 71af5309874269bcc9e4b84ea716fab33d888c1d (diff) | |
| download | musl-08869deb7efbda6e979886cb67e3d5843f92c2e8.tar.gz | |
add support for powerpc/powerpc64 unaligned relocations
R_PPC_UADDR32 (R_PPC64_UADDR64) has the same meaning as R_PPC_ADDR32
(R_PPC64_ADDR64), except that its address need not be aligned. For
powerpc64, BFD ld(1) will automatically convert between ADDR<->UADDR
relocations when the address is/isn't at its native alignment. This
will happen if, for example, there is a pointer in a packed struct.
gold and lld do not currently generate R_PPC64_UADDR64, but pass
through misaligned R_PPC64_ADDR64 relocations from object files,
possibly relaxing them to misaligned R_PPC64_RELATIVE. In both cases
(relaxed or not) this violates the PSABI, which defines the relevant
field type as "a 64-bit field occupying 8 bytes, the alignment of
which is 8 bytes unless otherwise specified."
All three linkers violate the PSABI on 32-bit powerpc, where the only
difference is that the field is 32 bits wide, aligned to 4 bytes.
Currently musl fails to load executables linked by BFD ld containing
R_PPC64_UADDR64, with the error "unsupported relocation type 43".
This change provides compatibility with BFD ld on powerpc64, and any
static linker on either architecture that starts following the PSABI
more closely.
| -rw-r--r-- | arch/powerpc/reloc.h | 1 | ||||
| -rw-r--r-- | arch/powerpc64/reloc.h | 1 | ||||
| -rw-r--r-- | ldso/dynlink.c | 3 | ||||
| -rw-r--r-- | src/internal/dynlink.h | 1 |
4 files changed, 6 insertions, 0 deletions
diff --git a/arch/powerpc/reloc.h b/arch/powerpc/reloc.h index 1b4cab36..527b6b7c 100644 --- a/arch/powerpc/reloc.h +++ b/arch/powerpc/reloc.h @@ -9,6 +9,7 @@ #define TPOFF_K (-0x7000) #define REL_SYMBOLIC R_PPC_ADDR32 +#define REL_USYMBOLIC R_PPC_UADDR32 #define REL_GOT R_PPC_GLOB_DAT #define REL_PLT R_PPC_JMP_SLOT #define REL_RELATIVE R_PPC_RELATIVE diff --git a/arch/powerpc64/reloc.h b/arch/powerpc64/reloc.h index faf70acd..5bdaeede 100644 --- a/arch/powerpc64/reloc.h +++ b/arch/powerpc64/reloc.h @@ -11,6 +11,7 @@ #define TPOFF_K (-0x7000) #define REL_SYMBOLIC R_PPC64_ADDR64 +#define REL_USYMBOLIC R_PPC64_UADDR64 #define REL_GOT R_PPC64_GLOB_DAT #define REL_PLT R_PPC64_JMP_SLOT #define REL_RELATIVE R_PPC64_RELATIVE diff --git a/ldso/dynlink.c b/ldso/dynlink.c index 531811cc..edd91acd 100644 --- a/ldso/dynlink.c +++ b/ldso/dynlink.c @@ -407,6 +407,9 @@ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stri case REL_PLT: *reloc_addr = sym_val + addend; break; + case REL_USYMBOLIC: + memcpy(reloc_addr, &(size_t){sym_val + addend}, sizeof(size_t)); + break; case REL_RELATIVE: *reloc_addr = (size_t)base + addend; break; diff --git a/src/internal/dynlink.h b/src/internal/dynlink.h index 165bbedb..ffd06b04 100644 --- a/src/internal/dynlink.h +++ b/src/internal/dynlink.h @@ -28,6 +28,7 @@ typedef Elf64_Sym Sym; enum { REL_NONE = 0, REL_SYMBOLIC = -100, + REL_USYMBOLIC, REL_GOT, REL_PLT, REL_RELATIVE, |