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242 lines
10 KiB
242 lines
10 KiB
9 months ago
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commit 23c1c256ae7b0f010d0fcaff60682b620887b164
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Author: Mihailo Stojanovic <mihailo.stojanovic@rt-rk.com>
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Date: Thu Aug 29 20:11:42 2019 +0000
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MIPS support for GNU hash
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This patch is a reimplementation of [1], which was submitted back in
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2015. Copyright issue has been sorted [2] last year. It proposed a new
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section (.gnu.xhash) and related dynamic tag (GT_GNU_XHASH). The new
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section would be virtually identical to the existing .gnu.hash except
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for the translation table (xlat) which would contain correct MIPS
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.dynsym indexes corresponding to the hashvals in chains. This is because
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MIPS ABI imposes a different ordering of the dynsyms than the one
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expected by the .gnu.hash section. Another addition would be a leading
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word at the beggining of the section, which would contain the number of
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entries in the translation table.
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In this patch, the new section name and dynamic tag are changed to
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reflect the fact that the section should be treated as MIPS specific
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(.MIPS.xhash and DT_MIPS_XHASH).
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This patch addresses the alignment issue reported in [3] which is caused
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by the leading word of the .MIPS.xhash section. Leading word is now
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removed in the corresponding binutils patch, and the number of entries
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in the translation table is computed using DT_MIPS_SYMTABNO dynamic tag.
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Since the MIPS specific dl-lookup.c file was removed following the
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initial patch submission, I opted for the definition of three new macros
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in the generic ldsodefs.h. ELF_MACHINE_GNU_HASH_ADDRIDX defines the
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index of the dynamic tag in the l_info array. ELF_MACHINE_HASH_SYMIDX is
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used to calculate the index of a symbol in GNU hash. On MIPS, it is
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defined to look up the symbol index in the translation table.
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ELF_MACHINE_XHASH_SETUP is defined for MIPS only. It initializes the
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.MIPS.xhash pointer in the link_map_machine struct.
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The other major change is bumping the highest EI_ABIVERSION value for
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MIPS to suggest that the dynamic linker now supports GNU hash.
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The patch was tested by running the glibc testsuite for the three MIPS
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ABIs (o32, n32 and n64) and for x86_64-linux-gnu.
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[1] https://sourceware.org/ml/binutils/2015-10/msg00057.html
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[2] https://sourceware.org/ml/binutils/2018-03/msg00025.html
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[3] https://sourceware.org/ml/binutils/2016-01/msg00006.html
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* elf/dl-addr.c (determine_info): Calculate the symbol index
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using the newly defined ELF_MACHINE_HASH_SYMIDX macro.
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* elf/dl-lookup.c (do_lookup_x): Ditto.
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(_dl_setup_hash): Initialize MIPS xhash translation table.
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* elf/elf.h (SHT_MIPS_XHASH): New define.
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(DT_MIPS_XHASH): New define.
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* sysdeps/generic/ldsodefs.h (ELF_MACHINE_GNU_HASH_ADDRIDX): New
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define.
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(ELF_MACHINE_HASH_SYMIDX): Ditto.
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(ELF_MACHINE_XHASH_SETUP): Ditto.
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* sysdeps/mips/ldsodefs.h (ELF_MACHINE_GNU_HASH_ADDRIDX): New
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define.
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(ELF_MACHINE_HASH_SYMIDX): Ditto.
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(ELF_MACHINE_XHASH_SETUP): Ditto.
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* sysdeps/mips/linkmap.h (struct link_map_machine): New member.
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* sysdeps/unix/sysv/linux/mips/ldsodefs.h: Increment valid ABI
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version.
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* sysdeps/unix/sysv/linux/mips/libc-abis: New ABI version.
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diff --git a/elf/dl-addr.c b/elf/dl-addr.c
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index e6c7d020945c51d2..b146fed09a46ff76 100644
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--- a/elf/dl-addr.c
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+++ b/elf/dl-addr.c
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@@ -42,7 +42,7 @@ determine_info (const ElfW(Addr) addr, struct link_map *match, Dl_info *info,
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ElfW(Word) strtabsize = match->l_info[DT_STRSZ]->d_un.d_val;
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const ElfW(Sym) *matchsym = NULL;
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- if (match->l_info[ADDRIDX (DT_GNU_HASH)] != NULL)
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+ if (match->l_info[ELF_MACHINE_GNU_HASH_ADDRIDX] != NULL)
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{
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/* We look at all symbol table entries referenced by the hash
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table. */
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@@ -57,6 +57,7 @@ determine_info (const ElfW(Addr) addr, struct link_map *match, Dl_info *info,
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{
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/* The hash table never references local symbols so
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we can omit that test here. */
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+ symndx = ELF_MACHINE_HASH_SYMIDX (match, hasharr);
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if ((symtab[symndx].st_shndx != SHN_UNDEF
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|| symtab[symndx].st_value != 0)
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&& symtab[symndx].st_shndx != SHN_ABS
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@@ -65,8 +66,6 @@ determine_info (const ElfW(Addr) addr, struct link_map *match, Dl_info *info,
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matchsym, addr)
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&& symtab[symndx].st_name < strtabsize)
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matchsym = (ElfW(Sym) *) &symtab[symndx];
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-
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- ++symndx;
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}
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while ((*hasharr++ & 1u) == 0);
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}
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diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c
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index 01724a54f8840f9f..42fdaed99296137f 100644
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--- a/elf/dl-lookup.c
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+++ b/elf/dl-lookup.c
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@@ -432,7 +432,7 @@ do_lookup_x (const char *undef_name, uint_fast32_t new_hash,
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do
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if (((*hasharr ^ new_hash) >> 1) == 0)
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{
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- symidx = hasharr - map->l_gnu_chain_zero;
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+ symidx = ELF_MACHINE_HASH_SYMIDX (map, hasharr);
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sym = check_match (undef_name, ref, version, flags,
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type_class, &symtab[symidx], symidx,
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strtab, map, &versioned_sym,
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@@ -961,10 +961,10 @@ _dl_setup_hash (struct link_map *map)
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{
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Elf_Symndx *hash;
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- if (__glibc_likely (map->l_info[ADDRIDX (DT_GNU_HASH)] != NULL))
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+ if (__glibc_likely (map->l_info[ELF_MACHINE_GNU_HASH_ADDRIDX] != NULL))
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{
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Elf32_Word *hash32
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- = (void *) D_PTR (map, l_info[ADDRIDX (DT_GNU_HASH)]);
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+ = (void *) D_PTR (map, l_info[ELF_MACHINE_GNU_HASH_ADDRIDX]);
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map->l_nbuckets = *hash32++;
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Elf32_Word symbias = *hash32++;
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Elf32_Word bitmask_nwords = *hash32++;
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@@ -979,6 +979,10 @@ _dl_setup_hash (struct link_map *map)
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map->l_gnu_buckets = hash32;
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hash32 += map->l_nbuckets;
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map->l_gnu_chain_zero = hash32 - symbias;
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+
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+ /* Initialize MIPS xhash translation table. */
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+ ELF_MACHINE_XHASH_SETUP (hash32, symbias, map);
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+
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return;
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}
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diff --git a/elf/elf.h b/elf/elf.h
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index 74f7f479ce817040..d6506ea1c7160dea 100644
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--- a/elf/elf.h
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+++ b/elf/elf.h
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@@ -1698,6 +1698,7 @@ typedef struct
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#define SHT_MIPS_EH_REGION 0x70000027
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#define SHT_MIPS_XLATE_OLD 0x70000028
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#define SHT_MIPS_PDR_EXCEPTION 0x70000029
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+#define SHT_MIPS_XHASH 0x7000002b
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/* Legal values for sh_flags field of Elf32_Shdr. */
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@@ -1945,7 +1946,9 @@ typedef struct
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in a PIE as it stores a relative offset from the address of the tag
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rather than an absolute address. */
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#define DT_MIPS_RLD_MAP_REL 0x70000035
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-#define DT_MIPS_NUM 0x36
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+/* GNU-style hash table with xlat. */
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+#define DT_MIPS_XHASH 0x70000036
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+#define DT_MIPS_NUM 0x37
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/* Legal values for DT_MIPS_FLAGS Elf32_Dyn entry. */
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diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
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index f0185ce0d16c0f69..3bdbdd6e67dacc85 100644
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--- a/sysdeps/generic/ldsodefs.h
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+++ b/sysdeps/generic/ldsodefs.h
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@@ -47,6 +47,23 @@ __BEGIN_DECLS
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#define ADDRIDX(tag) (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGNUM \
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+ DT_EXTRANUM + DT_VALNUM + DT_ADDRTAGIDX (tag))
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+/* Type of GNU hash which the machine uses. */
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+#ifndef ELF_MACHINE_GNU_HASH_ADDRIDX
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+# define ELF_MACHINE_GNU_HASH_ADDRIDX ADDRIDX (DT_GNU_HASH)
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+#endif
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+
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+/* Calculate the index of a symbol in GNU hash. */
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+#ifndef ELF_MACHINE_HASH_SYMIDX
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+# define ELF_MACHINE_HASH_SYMIDX(map, hasharr) \
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+ ((hasharr) - (map)->l_gnu_chain_zero)
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+#endif
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+
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+/* Setup MIPS xhash. Defined only for MIPS. */
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+#ifndef ELF_MACHINE_XHASH_SETUP
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+# define ELF_MACHINE_XHASH_SETUP(hash32, symbias, map) \
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+ ((void) (hash32), (void) (symbias), (void) (map))
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+#endif
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+
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/* We use this macro to refer to ELF types independent of the native wordsize.
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`ElfW(TYPE)' is used in place of `Elf32_TYPE' or `Elf64_TYPE'. */
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#define ELFW(type) _ElfW (ELF, __ELF_NATIVE_CLASS, type)
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diff --git a/sysdeps/mips/ldsodefs.h b/sysdeps/mips/ldsodefs.h
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index c6e5ce7e660325c1..35043b7c6d416c50 100644
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--- a/sysdeps/mips/ldsodefs.h
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+++ b/sysdeps/mips/ldsodefs.h
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@@ -26,6 +26,21 @@ struct La_mips_32_retval;
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struct La_mips_64_regs;
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struct La_mips_64_retval;
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+#define ELF_MACHINE_GNU_HASH_ADDRIDX (DT_MIPS_XHASH - DT_LOPROC + DT_NUM)
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+
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+/* Calculate the index of a symbol in MIPS xhash. */
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+#define ELF_MACHINE_HASH_SYMIDX(map, hasharr) \
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+ ((map)->l_mach.mips_xlat_zero[(hasharr) - (map)->l_gnu_chain_zero])
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+
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+/* Setup MIPS xhash. */
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+#define ELF_MACHINE_XHASH_SETUP(hash32, symbias, map) \
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+ do \
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+ { \
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+ (hash32) += (map)->l_info[DT_MIPS (SYMTABNO)]->d_un.d_val - (symbias); \
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+ (map)->l_mach.mips_xlat_zero = (hash32) - (symbias); \
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+ } \
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+ while (0)
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+
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#define ARCH_PLTENTER_MEMBERS \
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Elf32_Addr (*mips_o32_gnu_pltenter) (Elf32_Sym *, unsigned int, \
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uintptr_t *, uintptr_t *, \
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diff --git a/sysdeps/mips/linkmap.h b/sysdeps/mips/linkmap.h
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index 1fb9678a6d1625fd..1e640c3ba9bd18e4 100644
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--- a/sysdeps/mips/linkmap.h
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+++ b/sysdeps/mips/linkmap.h
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@@ -3,4 +3,5 @@ struct link_map_machine
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ElfW(Addr) plt; /* Address of .plt */
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ElfW(Word) fpabi; /* FP ABI of the object */
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unsigned int odd_spreg; /* Does the object require odd_spreg support? */
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+ const Elf32_Word *mips_xlat_zero; /* .MIPS.xhash */
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};
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diff --git a/sysdeps/unix/sysv/linux/mips/ldsodefs.h b/sysdeps/unix/sysv/linux/mips/ldsodefs.h
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index d2912cadabfd6877..03f3e12f202a0563 100644
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--- a/sysdeps/unix/sysv/linux/mips/ldsodefs.h
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+++ b/sysdeps/unix/sysv/linux/mips/ldsodefs.h
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@@ -34,7 +34,7 @@ extern void _dl_static_init (struct link_map *map);
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#undef VALID_ELF_ABIVERSION
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#define VALID_ELF_ABIVERSION(osabi,ver) \
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(ver == 0 \
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- || (osabi == ELFOSABI_SYSV && ver < 5) \
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+ || (osabi == ELFOSABI_SYSV && ver < 6) \
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|| (osabi == ELFOSABI_GNU && ver < LIBC_ABI_MAX))
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#endif /* ldsodefs.h */
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diff --git a/sysdeps/unix/sysv/linux/mips/libc-abis b/sysdeps/unix/sysv/linux/mips/libc-abis
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index eaea558720f42a48..c0b67dae3ece1511 100644
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--- a/sysdeps/unix/sysv/linux/mips/libc-abis
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+++ b/sysdeps/unix/sysv/linux/mips/libc-abis
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@@ -16,3 +16,5 @@ UNIQUE
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MIPS_O32_FP64 mips*-*-linux*
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# Absolute (SHN_ABS) symbols working correctly.
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ABSOLUTE
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+# GNU-style hash table with translation table.
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+MIPS_XHASH
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