February 2024 - devel

[PATCH] Fix broken compilation of uClibc-ng.
by Dmitry Chestnykh 18 Feb '24

18 Feb '24

During buildroot compilation with latest uClibc I've encoutered linking error due to multiple definition of some symbols from DNS code. The error happens because the same file resolv.c is included inside many other .c files: res_comp.c:(.text+0x0): multiple definition of `__GI___dn_expand'; libc/libc_so.a(encodeq.os):encodeq.c:(.text+0x8a0): first defined here res_comp.c:(.text+0x0): multiple definition of `__dn_expand'; libc/libc_so.a(encodeq.os):encodeq.c:(.text+0x8a0): first defined here res_comp.c:(.text+0x34): multiple definition of `__GI___dn_comp'; libc/libc_so.a(encodeq.os):encodeq.c:(.text+0xc68): first defined here res_comp.c:(.text+0x34): multiple definition of `__dn_comp'; libc/libc_so.a(encodeq.os):encodeq.c:(.text+0xc68): first defined here ns_name.c:(.text+0x4c): multiple definition of `__GI___ns_name_ntop'; libc/libc_so.a(encodeq.os):encodeq.c:(.text+0x4c): first defined here ns_name.c:(.text+0x4c): multiple definition of `__ns_name_ntop'; libc/libc_so.a(encodeq.os):encodeq.c:(.text+0x4c): first defined here ns_name.c:(.text+0x1f8): multiple definition of `__GI___ns_name_pton'; libc/libc_so.a(encodeq.os):encodeq.c:(.text+0x1f8): first defined here ns_name.c:(.text+0x1f8): multiple definition of `__ns_name_pton'; libc/libc_so.a(encodeq.os):encodeq.c:(.text+0x1f8): first defined here ns_name.c:(.text+0x624): multiple definition of `__hnbad'; libc/libc_so.a(encodeq.os):encodeq.c:(.text+0x624): first defined here ns_name.c:(.text+0x718): multiple definition of `__GI___ns_name_unpack'; libc/libc_so.a(encodeq.os):encodeq.c:(.text+0x718): first defined here ns_name.c:(.text+0x718): multiple definition of `__ns_name_unpack'; libc/libc_so.a(encodeq.os):encodeq.c:(.text+0x718): first defined here ns_name.c:(.text+0x84c): multiple definition of `__GI___ns_name_uncompress'; libc/libc_so.a(encodeq.os):encodeq.c:(.text+0x84c): first defined here ns_name.c:(.text+0x84c): multiple definition of `__ns_name_uncompress'; libc/libc_so.a(encodeq.os):encodeq.c:(.text+0x84c): first defined here ns_name.c:(.text+0x8a0): multiple definition of `__GI___ns_name_pack'; libc/libc_so.a(encodeq.os):encodeq.c:(.text+0x8d4): first defined here ns_name.c:(.text+0x8a0): multiple definition of `__ns_name_pack'; libc/libc_so.a(encodeq.os):encodeq.c:(.text+0x8d4): first defined here ns_name.c:(.text+0xbe4): multiple definition of `__GI___ns_name_compress'; libc/libc_so.a(encodeq.os):encodeq.c:(.text+0xc18): first defined here ns_name.c:(.text+0xbe4): multiple definition of `__ns_name_compress'; libc/libc_so.a(encodeq.os):encodeq.c:(.text+0xc18): first defined here ns_name.c:(.text+0xc34): multiple definition of `__GI___ns_name_skip'; libc/libc_so.a(encodeq.os):encodeq.c:(.text+0xcdc): first defined here ns_name.c:(.text+0xc34): multiple definition of `__ns_name_skip'; libc/libc_so.a(encodeq.os):encodeq.c:(.text+0xcdc): first defined here ns_name.c:(.text+0xcd4): multiple definition of `__GI___dn_skipname'; libc/libc_so.a(encodeq.os):encodeq.c:(.text+0xd7c): first defined here ns_name.c:(.text+0xcd4): multiple definition of `__dn_skipname'; libc/libc_so.a(encodeq.os):encodeq.c:(.text+0xd7c): first defined here My previous commit that fixes build error of DNS code is okay, but there are some 'bottlenecks' in uClibc-ng code, so if we don't want to completely rewrite resolv.c we need to make some symbols weak to prevent linking errors. --- libc/inet/resolv.c | 42 +++++++++++++++++++++--------------------- 1 file changed, 21 insertions(+), 21 deletions(-) diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c index 37842021c..d7a659a8c 100644 --- a/libc/inet/resolv.c +++ b/libc/inet/resolv.c @@ -2809,7 +2809,7 @@ libc_hidden_def(gethostbyaddr) * 'exp_dn' is a pointer to a buffer of size 'length' for the result. * Return size of compressed name or -1 if there was an error. */ -int dn_expand(const u_char *msg, const u_char *eom, const u_char *src, +int weak_function dn_expand(const u_char *msg, const u_char *eom, const u_char *src, char *dst, int dstsiz) { int n = ns_name_uncompress(msg, eom, src, dst, (size_t)dstsiz); @@ -2818,14 +2818,14 @@ int dn_expand(const u_char *msg, const u_char *eom, const u_char *src, dst[0] = '\0'; return n; } -libc_hidden_def(dn_expand) +libc_hidden_weak(dn_expand) /* * Pack domain name 'exp_dn' in presentation form into 'comp_dn'. * Return the size of the compressed name or -1. * 'length' is the size of the array pointed to by 'comp_dn'. */ -int +int weak_function dn_comp(const char *src, u_char *dst, int dstsiz, u_char **dnptrs, u_char **lastdnptr) { @@ -2833,7 +2833,7 @@ dn_comp(const char *src, u_char *dst, int dstsiz, (const u_char **) dnptrs, (const u_char **) lastdnptr); } -libc_hidden_def(dn_comp) +libc_hidden_weak(dn_comp) #endif /* L_res_comp */ @@ -2873,7 +2873,7 @@ static int special(int ch) * note: * Root domain returns as "." not "". */ -int ns_name_uncompress(const u_char *msg, const u_char *eom, +int weak_function ns_name_uncompress(const u_char *msg, const u_char *eom, const u_char *src, char *dst, size_t dstsiz) { u_char tmp[NS_MAXCDNAME]; @@ -2886,7 +2886,7 @@ int ns_name_uncompress(const u_char *msg, const u_char *eom, return -1; return n; } -libc_hidden_def(ns_name_uncompress) +libc_hidden_weak(ns_name_uncompress) /* * ns_name_ntop(src, dst, dstsiz) @@ -2897,7 +2897,7 @@ libc_hidden_def(ns_name_uncompress) * The root is returned as "." * All other domains are returned in non absolute form */ -int ns_name_ntop(const u_char *src, char *dst, size_t dstsiz) +int weak_function ns_name_ntop(const u_char *src, char *dst, size_t dstsiz) { const u_char *cp; char *dn, *eom; @@ -2967,7 +2967,7 @@ int ns_name_ntop(const u_char *src, char *dst, size_t dstsiz) *dn++ = '\0'; return (dn - dst); } -libc_hidden_def(ns_name_ntop) +libc_hidden_weak(ns_name_ntop) static int encode_bitstring(const char **bp, const char *end, unsigned char **labelp, @@ -3081,7 +3081,7 @@ static int encode_bitstring(const char **bp, const char *end, return 0; } -int ns_name_pton(const char *src, u_char *dst, size_t dstsiz) +int weak_function ns_name_pton(const char *src, u_char *dst, size_t dstsiz) { static const char digits[] = "0123456789"; u_char *label, *bp, *eom; @@ -3202,7 +3202,7 @@ int ns_name_pton(const char *src, u_char *dst, size_t dstsiz) errno = EMSGSIZE; return -1; } -libc_hidden_def(ns_name_pton) +libc_hidden_weak(ns_name_pton) /* * __hnbad(dotted) @@ -3218,7 +3218,7 @@ libc_hidden_def(ns_name_pton) * return: * 0 if the name is ok */ -int __hnbad(const char *dotted) +int weak_function __hnbad(const char *dotted) { unsigned char c, n, *cp; unsigned char buf[NS_MAXCDNAME]; @@ -3255,7 +3255,7 @@ int __hnbad(const char *dotted) * return: * -1 if it fails, or consumed octets if it succeeds. */ -int ns_name_unpack(const u_char *msg, const u_char *eom, const u_char *src, +int weak_function ns_name_unpack(const u_char *msg, const u_char *eom, const u_char *src, u_char *dst, size_t dstsiz) { const u_char *srcp, *dstlim; @@ -3322,7 +3322,7 @@ int ns_name_unpack(const u_char *msg, const u_char *eom, const u_char *src, len = srcp - src; return len; } -libc_hidden_def(ns_name_unpack) +libc_hidden_weak(ns_name_unpack) static int labellen(const unsigned char *lp) { @@ -3416,7 +3416,7 @@ next: return -1; } -int ns_name_pack(const unsigned char *src, +int weak_function ns_name_pack(const unsigned char *src, unsigned char *dst, int dstsiz, const unsigned char **dnptrs, const unsigned char **lastdnptr) @@ -3525,9 +3525,9 @@ cleanup: return dstp - dst; } -libc_hidden_def(ns_name_pack) +libc_hidden_weak(ns_name_pack) -int ns_name_compress(const char *src, +int weak_function ns_name_compress(const char *src, unsigned char *dst, size_t dstsiz, const unsigned char **dnptrs, const unsigned char **lastdnptr) @@ -3539,9 +3539,9 @@ int ns_name_compress(const char *src, return ns_name_pack(tmp, dst, dstsiz, dnptrs, lastdnptr); } -libc_hidden_def(ns_name_compress) +libc_hidden_weak(ns_name_compress) -int ns_name_skip(const unsigned char **ptrptr, +int weak_function ns_name_skip(const unsigned char **ptrptr, const unsigned char *eom) { const unsigned char *cp; @@ -3583,9 +3583,9 @@ int ns_name_skip(const unsigned char **ptrptr, return 0; } -libc_hidden_def(ns_name_skip) +libc_hidden_weak(ns_name_skip) -int dn_skipname(const unsigned char *ptr, const unsigned char *eom) +int weak_function dn_skipname(const unsigned char *ptr, const unsigned char *eom) { const unsigned char *saveptr = ptr; @@ -3594,7 +3594,7 @@ int dn_skipname(const unsigned char *ptr, const unsigned char *eom) return ptr - saveptr; } -libc_hidden_def(dn_skipname) +libc_hidden_weak(dn_skipname) #endif /* L_ns_name */ -- 2.43.2

3 2

[PATCH] features.h: Rework _DEFAULT_SOURCE
by Paul Cercueil 18 Feb '24

18 Feb '24

The (glibc) documentation for _DEFAULT_SOURCE states: The "default" definitions comprise those required by POSIX.1-2008 and ISO C99, as well as various definitions originally derived from BSD and System V. On glibc 2.19 and earlier, these defaults were approximately equivalent to explicitly defining the following: cc -D_BSD_SOURCE -D_SVID_SOURCE -D_POSIX_C_SOURCE=200809 It also states that _BSD_SOURCE and _SVID_SOURCE are deprecated, and have the same effect as setting _DEFAULT_SOURCE. Therefore, when any of _BSD_SOURCE, _SVID_SOURCE or _DEFAULT_SOURCE is set, the three macros should be set, and POSIX 2008.09 compatibility should be enabled. Signed-off-by: Paul Cercueil <paul(a)crapouillou.net> --- include/features.h | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/include/features.h b/include/features.h index d6e45c2ff..11b34205f 100644 --- a/include/features.h +++ b/include/features.h @@ -40,7 +40,8 @@ _SVID_SOURCE ISO C, POSIX, and SVID things. _ATFILE_SOURCE Additional *at interfaces. _GNU_SOURCE All of the above, plus GNU extensions. - _DEFAULT_SOURCE Equivalent to defining _BSD_SOURCE and _SVID_SOURCE. + _DEFAULT_SOURCE Equivalent to defining _BSD_SOURCE and _SVID_SOURCE, + as well as _POSIX_C_SOURCE=200809L. _REENTRANT Select additionally reentrant object. _THREAD_SAFE Same as _REENTRANT, often used by other systems. _FORTIFY_SOURCE If set to numeric value > 0 additional security @@ -142,18 +143,19 @@ /* Whether to use feature set F. */ #define __GLIBC_USE(F) __GLIBC_USE_ ## F -/* _DEFAULT_SOURCE is equivalent to defining _BSD_SOURCE and _SVID_SOURCE - * and vice versa. */ -#ifdef _DEFAULT_SOURCE +/* _DEFAULT_SOURCE is equivalent to defining _BSD_SOURCE, _SVID_SOURCE + * and _POSIX_C_SOURCE=200809L and vice versa. */ +#if defined _DEFAULT_SOURCE || defined _BSD_SOURCE || defined _SVID_SOURCE +# undef _DEFAULT_SOURCE +# define _DEFAULT_SOURCE 1 # undef _BSD_SOURCE # define _BSD_SOURCE 1 # undef _SVID_SOURCE # define _SVID_SOURCE 1 -#endif - -#if defined _BSD_SOURCE || defined _SVID_SOURCE -# undef _DEFAULT_SOURCE -# define _DEFAULT_SOURCE 1 +# if _POSIX_C_SOURCE < 200809L +# undef _POSIX_C_SOURCE +# define _POSIX_C_SOURCE 200809L +# endif #endif /* If _GNU_SOURCE was defined by the user, turn on all the other features. */ -- 2.43.0

2 1

[PATCH] Add extra `-shared` to link.so command.
by Dmitry Chestnykh 11 Feb '24

11 Feb '24

While compiling OpenADK I discovered that there may be a case where UCLIBC_EXTRA_LDFLAGS contains `-fpie -pie`. Linker ignores `-shared` if `-pie` flag is passed after and produces an executable binary instead of shared object. This leads to linking failure because `ld-uClibc.so.1` becomes executable instead of shared object. `ld-uClibc.so.1` is used as one of the inputs when linking of libc.so.1 and linking proccess fails. To prevent this issue we need to pass extra `-shared` flag in `link.so` target command after all other flags to overwrite `-pie` effect. Signed-off-by: Dmitry Chestnykh <dm.chestnykh(a)gmail.com> --- Makerules | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Makerules b/Makerules index 1a7443c39..fe8a7916e 100644 --- a/Makerules +++ b/Makerules @@ -334,7 +334,7 @@ define link.so -Wl,-soname=$(notdir $(a)).$(2) \ $(CFLAG_-nostdlib) $(CFLAG_-nostartfiles) \ -o $(dir $@)$(1) $(START_FILE-$(notdir $@)) \ - -Wl,--whole-archive $(firstword $^) -Wl,--no-whole-archive \ + -Wl,--whole-archive $(firstword $^) -Wl,--no-whole-archive -shared \ $(LIBS-$(notdir $@)) $(LIBGCC) $(END_FILE-$(notdir $@)) $(Q)$(LN) -sf $(1) $@.$(2) $(Q)$(LN) -sf $(1) $@ -- 2.43.0

2 1

[PATCH] libc: Fix dns-related build issues.
by Dmitry Chestnykh 10 Feb '24

10 Feb '24

- The first observed issue is linking failure: ` /usr/bin/ld: libc/libc_so.a(encodeq.os): in function `__encode_question': encodeq.c:(.text+0x16): undefined reference to `__GI___dn_comp' /usr/bin/ld: libc/libc_so.a(dnslookup.os): in function `__dns_lookup': dnslookup.c:(.text+0x6fb): undefined reference to `__GI___dn_expand' /usr/bin/ld: dnslookup.c:(.text+0x7ab): undefined reference to `__hnbad' collect2: error: ld returned 1 exit status ` The root cause is that the resolv.c file contains some functions (dn_comp, dn_expand, __hnbad) under `#ifdef L_ns_name` and `#ifdef L_ns_comp` which wasn't defined, so we had undefined refs to such functions. - The second issue is misleading indentation inside `ns_name_pack`. ` libc/inet/resolv.c: In function '__ns_name_pack': libc/inet/resolv.c:3519:17: warning: this 'if' clause does not guard... 3519 | if (msg != NULL) ... ./include/errno.h:73:18: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if' 73 | # define errno errno /* For #ifndef errno tests. */ | ^~~~~ libc/inet/resolv.c:3522:25: note: in expansion of macro 'errno' 3522 | errno = EMSGSIZE; ` Signed-off-by: Dmitry Chestnykh <dm.chestnykh(a)gmail.com> --- libc/inet/encodeq.c | 2 ++ libc/inet/resolv.c | 4 ++-- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/libc/inet/encodeq.c b/libc/inet/encodeq.c index 5555aa548..dc7945bc6 100644 --- a/libc/inet/encodeq.c +++ b/libc/inet/encodeq.c @@ -5,4 +5,6 @@ */ #define L_encodeq +#define L_ns_name +#define L_res_comp #include RESOLVER diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c index 2f627ca08..37842021c 100644 --- a/libc/inet/resolv.c +++ b/libc/inet/resolv.c @@ -3519,8 +3519,8 @@ cleanup: if (msg != NULL) *lpp = NULL; - errno = EMSGSIZE; - return -1; + errno = EMSGSIZE; + return -1; } return dstp - dst; -- 2.43.0

3 3

[PATCH 1/2] sys/stat.h: Make S_ISSOCK() available if __USE_XOPEN2K
by Paul Cercueil 09 Feb '24

09 Feb '24

The S_ISSOCK() macro is present in POSIX 2001.12. Signed-off-by: Paul Cercueil <paul(a)crapouillou.net> --- include/sys/stat.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/include/sys/stat.h b/include/sys/stat.h index b6480bf97..6b6ff0047 100644 --- a/include/sys/stat.h +++ b/include/sys/stat.h @@ -117,7 +117,8 @@ __BEGIN_DECLS # ifdef __S_IFLNK # define S_IFLNK __S_IFLNK # endif -# if (defined __USE_BSD || defined __USE_MISC || defined __USE_UNIX98) \ +# if (defined __USE_BSD || defined __USE_MISC || defined __USE_UNIX98 \ + || defined __USE_XOPEN2K) \ && defined __S_IFSOCK # define S_IFSOCK __S_IFSOCK # endif @@ -142,7 +143,7 @@ __BEGIN_DECLS # define S_ISLNK(mode) 0 #endif -#if (defined __USE_BSD || defined __USE_UNIX98) \ +#if (defined __USE_BSD || defined __USE_UNIX98 || defined __USE_XOPEN2K) \ && defined __S_IFSOCK # define S_ISSOCK(mode) __S_ISTYPE((mode), __S_IFSOCK) #endif -- 2.43.0

2 2

[PATCH] ld.so: Add support of DT_RELR relocation format.
by Dmitry Chestnykh 09 Feb '24

09 Feb '24

Nowadays modern libcs like Glibc and musl currently support processing of RELATIVE relocations compressed with DT_RELR format. However I have noticed that uClibc-ng doesn't support this feature and if the source will be linked with `-Wl,-z,pack-relative-relos` (bfd) or `-Wl,--pack-dyn-relocs=relr` (lld) then ld.so cannot properly load the produced DSO. This patch is intended to fix this issue and adds applying of DT_RELR relative relocation. Signed-off-by: Dmitry Chestnykh <dm.chestnykh(a)gmail.com> --- include/elf.h | 8 +++++- ldso/include/dl-elf.h | 38 ++++++++++++++++++++++++++ ldso/ldso/dl-elf.c | 3 ++ ldso/ldso/dl-startup.c | 3 ++ libc/misc/internals/reloc_static_pie.c | 1 + 5 files changed, 52 insertions(+), 1 deletion(-) diff --git a/include/elf.h b/include/elf.h index b7edbade2..c2efa9978 100644 --- a/include/elf.h +++ b/include/elf.h @@ -60,6 +60,9 @@ typedef uint16_t Elf64_Section; typedef Elf32_Half Elf32_Versym; typedef Elf64_Half Elf64_Versym; +/* Type for relative relocations in DT_RELR format */ +typedef Elf32_Word Elf32_Relr; +typedef Elf64_Xword Elf64_Relr; /* The ELF file header. This appears at the start of every ELF file. */ @@ -818,7 +821,10 @@ typedef struct #define DT_ENCODING 32 /* Start of encoded range */ #define DT_PREINIT_ARRAY 32 /* Array with addresses of preinit fct*/ #define DT_PREINIT_ARRAYSZ 33 /* size in bytes of DT_PREINIT_ARRAY */ -#define DT_NUM 34 /* Number used */ +#define DT_RELRSZ 35 /* Size in bytes, of DT_RELR table */ +#define DT_RELR 36 /* Address of Relr relocs */ +#define DT_RELRENT 37 /* Size in bytes of one DT_RELR entry */ +#define DT_NUM 38 /* Number used */ #define DT_LOOS 0x6000000d /* Start of OS-specific */ #define DT_HIOS 0x6ffff000 /* End of OS-specific */ #define DT_LOPROC 0x70000000 /* Start of processor-specific */ diff --git a/ldso/include/dl-elf.h b/ldso/include/dl-elf.h index 2b99958d9..10b895733 100644 --- a/ldso/include/dl-elf.h +++ b/ldso/include/dl-elf.h @@ -250,5 +250,43 @@ unsigned int __dl_parse_dynamic_info(ElfW(Dyn) *dpnt, unsigned long dynamic_info (((X) & PF_W) ? PROT_WRITE : 0) | \ (((X) & PF_X) ? PROT_EXEC : 0)) +/* Apply relocations in DT_RELR format */ +#define DL_DO_RELOCATE_RELR(load_addr, relr_start, relr_end) \ + do { \ + const ElfW(Relr) *relr = 0; \ + ElfW(Addr) *reloc_addr = 0; \ + for (relr = relr_start; relr < relr_end; relr++) { \ + ElfW(Relr) relr_entry = *relr; \ + if (!(relr_entry & 1)) \ + { \ + reloc_addr = (ElfW(Addr) *)DL_RELOC_ADDR(load_addr, relr_entry); \ + *reloc_addr = (ElfW(Addr))DL_RELOC_ADDR(load_addr, reloc_addr); \ + reloc_addr++; \ + } \ + else \ + { \ + for (long int i = 0; (relr_entry >>= 1) != 0; ++i) { \ + if ((relr_entry & 1) != 0) \ + reloc_addr[i] = (ElfW(Addr))DL_RELOC_ADDR(load_addr, reloc_addr[i]); \ + } \ + reloc_addr += CHAR_BIT * sizeof(ElfW(Relr)) - 1; \ + } \ + } \ + } while (0); + +/* The macro to prepare data for the above DL_DO_RELOCATE_RELR */ +#define DL_RELOCATE_RELR(dyn) \ + do { \ + if (dyn->dynamic_info[DT_RELRENT]) \ + _dl_assert(dyn->dynamic_info[DT_RELRENT] == sizeof(ElfW(Relr))); \ + if (dyn->dynamic_info[DT_RELR] && \ + dyn->dynamic_info[DT_RELRSZ]) { \ + ElfW(Relr) *relr_start = (ElfW(Relr) *)((ElfW(Addr))dyn->loadaddr + (ElfW(Addr))dyn->dynamic_info[DT_RELR]); \ + ElfW(Relr) *relr_end = (ElfW(Relr) *)((const char *)relr_start + dyn->dynamic_info[DT_RELRSZ]); \ + _dl_if_debug_dprint("Relocating DT_RELR in %s: start:%p, end:%p\n", \ + dyn->libname, (void *)relr_start, (void *)relr_end); \ + DL_DO_RELOCATE_RELR(dyn->loadaddr, relr_start, relr_end); \ + } \ + } while (0); #endif /* _DL_ELF_H */ diff --git a/ldso/ldso/dl-elf.c b/ldso/ldso/dl-elf.c index 8210a012e..cc42b904f 100644 --- a/ldso/ldso/dl-elf.c +++ b/ldso/ldso/dl-elf.c @@ -1027,6 +1027,9 @@ int _dl_fixup(struct dyn_elf *rpnt, struct r_scope_elem *scope, int now_flag) return goof; } + /* Process DT_RELR relative relocations */ + DL_RELOCATE_RELR(tpnt); + reloc_size = tpnt->dynamic_info[DT_RELOC_TABLE_SIZE]; /* On some machines, notably SPARC & PPC, DT_REL* includes DT_JMPREL in its range. Note that according to the ELF spec, this is completely legal! */ diff --git a/ldso/ldso/dl-startup.c b/ldso/ldso/dl-startup.c index 989711fcc..674c4b7b9 100644 --- a/ldso/ldso/dl-startup.c +++ b/ldso/ldso/dl-startup.c @@ -264,6 +264,9 @@ DL_START(unsigned long args) that once we are done, we have considerably more flexibility. */ SEND_EARLY_STDERR_DEBUG("About to do library loader relocations\n"); + /* Process DT_RELR relative relocations */ + DL_RELOCATE_RELR(tpnt); + { int indx; #if defined(ELF_MACHINE_PLTREL_OVERLAP) diff --git a/libc/misc/internals/reloc_static_pie.c b/libc/misc/internals/reloc_static_pie.c index ab1923024..7ad80f97b 100644 --- a/libc/misc/internals/reloc_static_pie.c +++ b/libc/misc/internals/reloc_static_pie.c @@ -53,6 +53,7 @@ reloc_static_pie(ElfW(Addr) load_addr) PERFORM_BOOTSTRAP_GOT(tpnt); #endif + DL_RELOCATE_RELR(tpnt); #if defined(ELF_MACHINE_PLTREL_OVERLAP) # define INDX_MAX 1 -- 2.43.0

3 6

[PATCH] Fix redefinition of _GNU_SOURCE.
by Dmitry Chestnykh 09 Feb '24

09 Feb '24

libc/misc/getloadavg/getloadavg.c:26: warning: "_GNU_SOURCE" redefined 26 | #define _GNU_SOURCE | In file included from <command-line>: ./include/libc-symbols.h:52: note: this is the location of the previous definition 52 | #define _GNU_SOURCE 1 Signed-off-by: Dmitry Chestnykh <dm.chestnykh(a)gmail.com> --- libc/misc/getloadavg/getloadavg.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/libc/misc/getloadavg/getloadavg.c b/libc/misc/getloadavg/getloadavg.c index 2aee565c0..0d98119a9 100644 --- a/libc/misc/getloadavg/getloadavg.c +++ b/libc/misc/getloadavg/getloadavg.c @@ -23,7 +23,9 @@ * Imported from musl C library */ +#ifndef _GNU_SOURCE #define _GNU_SOURCE +#endif /* _GNU_SOURCE */ #include <stdlib.h> #include <sys/sysinfo.h> -- 2.43.0

2 1

[PATCH] ld.so: Add support of DT_RELR relocation format.
by Dmitry Chestnykh 06 Feb '24

06 Feb '24

Nowadays modern libcs like Glibc and musl currently support processing of RELATIVE relocations compressed with DT_RELR format. However I have noticed that uClibc-ng doesn't support this feature and if the source will be linked with `-Wl,-z,pack-relative-relos` (bfd) or `-Wl,--pack-dyn-relocs=relr` (lld) then ld.so cannot properly load the produced DSO. This patch is intended to fix this issue and adds applying of DT_RELR relative relocation. --- include/elf.h | 8 +++++- ldso/include/dl-elf.h | 38 ++++++++++++++++++++++++++ ldso/ldso/dl-elf.c | 3 ++ ldso/ldso/dl-startup.c | 3 ++ libc/misc/internals/reloc_static_pie.c | 1 + 5 files changed, 52 insertions(+), 1 deletion(-) diff --git a/include/elf.h b/include/elf.h index b7edbade2..c2efa9978 100644 --- a/include/elf.h +++ b/include/elf.h @@ -60,6 +60,9 @@ typedef uint16_t Elf64_Section; typedef Elf32_Half Elf32_Versym; typedef Elf64_Half Elf64_Versym; +/* Type for relative relocations in DT_RELR format */ +typedef Elf32_Word Elf32_Relr; +typedef Elf64_Xword Elf64_Relr; /* The ELF file header. This appears at the start of every ELF file. */ @@ -818,7 +821,10 @@ typedef struct #define DT_ENCODING 32 /* Start of encoded range */ #define DT_PREINIT_ARRAY 32 /* Array with addresses of preinit fct*/ #define DT_PREINIT_ARRAYSZ 33 /* size in bytes of DT_PREINIT_ARRAY */ -#define DT_NUM 34 /* Number used */ +#define DT_RELRSZ 35 /* Size in bytes, of DT_RELR table */ +#define DT_RELR 36 /* Address of Relr relocs */ +#define DT_RELRENT 37 /* Size in bytes of one DT_RELR entry */ +#define DT_NUM 38 /* Number used */ #define DT_LOOS 0x6000000d /* Start of OS-specific */ #define DT_HIOS 0x6ffff000 /* End of OS-specific */ #define DT_LOPROC 0x70000000 /* Start of processor-specific */ diff --git a/ldso/include/dl-elf.h b/ldso/include/dl-elf.h index 2b99958d9..10b895733 100644 --- a/ldso/include/dl-elf.h +++ b/ldso/include/dl-elf.h @@ -250,5 +250,43 @@ unsigned int __dl_parse_dynamic_info(ElfW(Dyn) *dpnt, unsigned long dynamic_info (((X) & PF_W) ? PROT_WRITE : 0) | \ (((X) & PF_X) ? PROT_EXEC : 0)) +/* Apply relocations in DT_RELR format */ +#define DL_DO_RELOCATE_RELR(load_addr, relr_start, relr_end) \ + do { \ + const ElfW(Relr) *relr = 0; \ + ElfW(Addr) *reloc_addr = 0; \ + for (relr = relr_start; relr < relr_end; relr++) { \ + ElfW(Relr) relr_entry = *relr; \ + if (!(relr_entry & 1)) \ + { \ + reloc_addr = (ElfW(Addr) *)DL_RELOC_ADDR(load_addr, relr_entry); \ + *reloc_addr = (ElfW(Addr))DL_RELOC_ADDR(load_addr, reloc_addr); \ + reloc_addr++; \ + } \ + else \ + { \ + for (long int i = 0; (relr_entry >>= 1) != 0; ++i) { \ + if ((relr_entry & 1) != 0) \ + reloc_addr[i] = (ElfW(Addr))DL_RELOC_ADDR(load_addr, reloc_addr[i]); \ + } \ + reloc_addr += CHAR_BIT * sizeof(ElfW(Relr)) - 1; \ + } \ + } \ + } while (0); + +/* The macro to prepare data for the above DL_DO_RELOCATE_RELR */ +#define DL_RELOCATE_RELR(dyn) \ + do { \ + if (dyn->dynamic_info[DT_RELRENT]) \ + _dl_assert(dyn->dynamic_info[DT_RELRENT] == sizeof(ElfW(Relr))); \ + if (dyn->dynamic_info[DT_RELR] && \ + dyn->dynamic_info[DT_RELRSZ]) { \ + ElfW(Relr) *relr_start = (ElfW(Relr) *)((ElfW(Addr))dyn->loadaddr + (ElfW(Addr))dyn->dynamic_info[DT_RELR]); \ + ElfW(Relr) *relr_end = (ElfW(Relr) *)((const char *)relr_start + dyn->dynamic_info[DT_RELRSZ]); \ + _dl_if_debug_dprint("Relocating DT_RELR in %s: start:%p, end:%p\n", \ + dyn->libname, (void *)relr_start, (void *)relr_end); \ + DL_DO_RELOCATE_RELR(dyn->loadaddr, relr_start, relr_end); \ + } \ + } while (0); #endif /* _DL_ELF_H */ diff --git a/ldso/ldso/dl-elf.c b/ldso/ldso/dl-elf.c index 8210a012e..cc42b904f 100644 --- a/ldso/ldso/dl-elf.c +++ b/ldso/ldso/dl-elf.c @@ -1027,6 +1027,9 @@ int _dl_fixup(struct dyn_elf *rpnt, struct r_scope_elem *scope, int now_flag) return goof; } + /* Process DT_RELR relative relocations */ + DL_RELOCATE_RELR(tpnt); + reloc_size = tpnt->dynamic_info[DT_RELOC_TABLE_SIZE]; /* On some machines, notably SPARC & PPC, DT_REL* includes DT_JMPREL in its range. Note that according to the ELF spec, this is completely legal! */ diff --git a/ldso/ldso/dl-startup.c b/ldso/ldso/dl-startup.c index 989711fcc..674c4b7b9 100644 --- a/ldso/ldso/dl-startup.c +++ b/ldso/ldso/dl-startup.c @@ -264,6 +264,9 @@ DL_START(unsigned long args) that once we are done, we have considerably more flexibility. */ SEND_EARLY_STDERR_DEBUG("About to do library loader relocations\n"); + /* Process DT_RELR relative relocations */ + DL_RELOCATE_RELR(tpnt); + { int indx; #if defined(ELF_MACHINE_PLTREL_OVERLAP) diff --git a/libc/misc/internals/reloc_static_pie.c b/libc/misc/internals/reloc_static_pie.c index ab1923024..7ad80f97b 100644 --- a/libc/misc/internals/reloc_static_pie.c +++ b/libc/misc/internals/reloc_static_pie.c @@ -53,6 +53,7 @@ reloc_static_pie(ElfW(Addr) load_addr) PERFORM_BOOTSTRAP_GOT(tpnt); #endif + DL_RELOCATE_RELR(tpnt); #if defined(ELF_MACHINE_PLTREL_OVERLAP) # define INDX_MAX 1 -- 2.43.0

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