Date: Wed, 27 May 2020 21:56:45 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-12@freebsd.org Subject: svn commit: r361564 - in stable/12: cddl/contrib/opensolaris/lib/libdtrace/common lib/libc/gen libexec/rtld-elf sys/sys Message-ID: <202005272156.04RLujAJ091465@repo.freebsd.org>
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Author: kib Date: Wed May 27 21:56:45 2020 New Revision: 361564 URL: https://svnweb.freebsd.org/changeset/base/361564 Log: MFC r361303, r361349, r361394, r361398, r361537: Change link_map::l_addr to mean load offset in ABI-compatible way. Add link_map::l_refname. Add rtld feature indicators. Modified: stable/12/cddl/contrib/opensolaris/lib/libdtrace/common/drti.c stable/12/lib/libc/gen/dlinfo.3 stable/12/libexec/rtld-elf/Symbol.map stable/12/libexec/rtld-elf/rtld.1 stable/12/libexec/rtld-elf/rtld.c stable/12/sys/sys/link_elf.h Directory Properties: stable/12/ (props changed) Modified: stable/12/cddl/contrib/opensolaris/lib/libdtrace/common/drti.c ============================================================================== --- stable/12/cddl/contrib/opensolaris/lib/libdtrace/common/drti.c Wed May 27 21:44:26 2020 (r361563) +++ stable/12/cddl/contrib/opensolaris/lib/libdtrace/common/drti.c Wed May 27 21:56:45 2020 (r361564) @@ -143,12 +143,18 @@ dtrace_dof_init(void) return; } +#ifdef __FreeBSD__ + elf = (void *)lmp->l_base; +#else elf = (void *)lmp->l_addr; +#endif dh.dofhp_dof = (uintptr_t)dof; - dh.dofhp_addr = elf->e_type == ET_DYN ? (uintptr_t) lmp->l_addr : 0; #ifdef __FreeBSD__ + dh.dofhp_addr = elf->e_type == ET_DYN ? (uintptr_t) lmp->l_base : 0; dh.dofhp_pid = getpid(); +#else + dh.dofhp_addr = elf->e_type == ET_DYN ? (uintptr_t) lmp->l_addr : 0; #endif if (lmid == 0) { Modified: stable/12/lib/libc/gen/dlinfo.3 ============================================================================== --- stable/12/lib/libc/gen/dlinfo.3 Wed May 27 21:44:26 2020 (r361563) +++ stable/12/lib/libc/gen/dlinfo.3 Wed May 27 21:56:45 2020 (r361564) @@ -25,7 +25,7 @@ .\" .\" $FreeBSD$ .\" -.Dd February 14, 2003 +.Dd May 21, 2020 .Dt DLINFO 3 .Os .Sh NAME @@ -105,14 +105,16 @@ structure is defined in .In link.h and has the following members: .Bd -literal -offset indent -caddr_t l_addr; /* Base Address of library */ +caddr_t l_base; /* Base Address of library */ const char *l_name; /* Absolute Path to Library */ const void *l_ld; /* Pointer to .dynamic in memory */ struct link_map *l_next, /* linked list of mapped libs */ *l_prev; +caddr_t l_addr; /* Load Offset of library */ +const char *l_refname; /* Object this one filters for */ .Ed .Bl -tag -width ".Va l_addr" -.It Va l_addr +.It Va l_base The base address of the object loaded into memory. .It Va l_name The full name of the loaded shared object. @@ -128,6 +130,15 @@ structure on the link-map list. The previous .Vt Link_map structure on the link-map list. +.It Va l_addr +The load offset of the object, that is, the difference between +the actual load address and the base virtual address the object +was linked at. +.It Va l_refname +A name of the object this object filters for, if any. +If there are more then one filtee, a name from the first +.Dv DT_FILTER +dynamic entry is supplied. .El .It Dv RTLD_DI_SERINFO Retrieve the library search paths associated with the given Modified: stable/12/libexec/rtld-elf/Symbol.map ============================================================================== --- stable/12/libexec/rtld-elf/Symbol.map Wed May 27 21:44:26 2020 (r361563) +++ stable/12/libexec/rtld-elf/Symbol.map Wed May 27 21:56:45 2020 (r361564) @@ -32,4 +32,6 @@ FBSDprivate_1.0 { _rtld_get_stack_prot; _rtld_is_dlopened; _r_debug_postinit; + _rtld_version__FreeBSD_version; + _rtld_version_laddr_offset; }; Modified: stable/12/libexec/rtld-elf/rtld.1 ============================================================================== --- stable/12/libexec/rtld-elf/rtld.1 Wed May 27 21:44:26 2020 (r361563) +++ stable/12/libexec/rtld-elf/rtld.1 Wed May 27 21:56:45 2020 (r361564) @@ -355,6 +355,54 @@ ignores and is naturally prone to race conditions. Environments which rely on such restrictions are weak and breakable on their own. +.Sh VERSIONING +Newer +.Nm +might provide some features or changes in runtime behavior that cannot be +easily detected at runtime by checking of the normal exported symbols. +Note that it is almost always wrong to verify +.Dv __FreeBSD_version +in userspace to detect features, either at compile or at run time, +because either kernel, or libc, or environment variables could not +match the running +.Nm . +.Pp +To solve the problem, +.Nm +exports some feature indicators in the +.Fx +private symbols namespace +.Dv FBSDprivate_1.0 . +Symbols start with the +.Dv _rtld_version +prefix. +Current list of defined symbols and corresponding features is: +.Bl -tag -width indent +.It Dv _rtld_version__FreeBSD_version +Symbol exports the value of the +.Dv __FreeBSD_version +definition as it was provided during the +.Nm +build. +The symbol is always present since the +.Dv _rtld_version +facility was introduced. +.It Dv _rtld_version_laddr_offset +The +.Va l_addr +member of the +.Vt link_map +structure contains the load offset of the shared object. +Before that, +.Va l_addr +contained the base address of the library. +See +.Xr dlinfo 3 . +.Pp +Also it indicates the presence of +.Va l_refname +member of the structure. +.El .Sh FILES .Bl -tag -width ".Pa /var/run/ld-elf32.so.hints" -compact .It Pa /var/run/ld-elf.so.hints @@ -369,6 +417,7 @@ The libmap configuration file for 32-bit binaries on 6 .Sh SEE ALSO .Xr ld 1 , .Xr ldd 1 , +.Xr dlinfo 3 , .Xr capsicum 4 , .Xr elf 5 , .Xr libmap.conf 5 , Modified: stable/12/libexec/rtld-elf/rtld.c ============================================================================== --- stable/12/libexec/rtld-elf/rtld.c Wed May 27 21:44:26 2020 (r361563) +++ stable/12/libexec/rtld-elf/rtld.c Wed May 27 21:56:45 2020 (r361564) @@ -1171,6 +1171,9 @@ digest_dynamic1(Obj_Entry *obj, int early, const Elf_D *needed_filtees_tail = nep; needed_filtees_tail = &nep->next; + + if (obj->linkmap.l_refname == NULL) + obj->linkmap.l_refname = (char *)dynp->d_un.d_val; } break; @@ -1353,6 +1356,10 @@ digest_dynamic1(Obj_Entry *obj, int early, const Elf_D } obj->dynsymcount += obj->symndx_gnu; } + + if (obj->linkmap.l_refname != NULL) + obj->linkmap.l_refname = obj->strtab + (unsigned long)obj-> + linkmap.l_refname; } static bool @@ -3981,52 +3988,50 @@ rtld_dirname_abs(const char *path, char *base) static void linkmap_add(Obj_Entry *obj) { - struct link_map *l = &obj->linkmap; - struct link_map *prev; + struct link_map *l, *prev; - obj->linkmap.l_name = obj->path; - obj->linkmap.l_addr = obj->mapbase; - obj->linkmap.l_ld = obj->dynamic; -#ifdef __mips__ - /* GDB needs load offset on MIPS to use the symbols */ - obj->linkmap.l_offs = obj->relocbase; -#endif + l = &obj->linkmap; + l->l_name = obj->path; + l->l_base = obj->mapbase; + l->l_ld = obj->dynamic; + l->l_addr = obj->relocbase; - if (r_debug.r_map == NULL) { - r_debug.r_map = l; - return; - } + if (r_debug.r_map == NULL) { + r_debug.r_map = l; + return; + } - /* - * Scan to the end of the list, but not past the entry for the - * dynamic linker, which we want to keep at the very end. - */ - for (prev = r_debug.r_map; - prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap; - prev = prev->l_next) - ; + /* + * Scan to the end of the list, but not past the entry for the + * dynamic linker, which we want to keep at the very end. + */ + for (prev = r_debug.r_map; + prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap; + prev = prev->l_next) + ; - /* Link in the new entry. */ - l->l_prev = prev; - l->l_next = prev->l_next; - if (l->l_next != NULL) - l->l_next->l_prev = l; - prev->l_next = l; + /* Link in the new entry. */ + l->l_prev = prev; + l->l_next = prev->l_next; + if (l->l_next != NULL) + l->l_next->l_prev = l; + prev->l_next = l; } static void linkmap_delete(Obj_Entry *obj) { - struct link_map *l = &obj->linkmap; + struct link_map *l; - if (l->l_prev == NULL) { - if ((r_debug.r_map = l->l_next) != NULL) - l->l_next->l_prev = NULL; - return; - } + l = &obj->linkmap; + if (l->l_prev == NULL) { + if ((r_debug.r_map = l->l_next) != NULL) + l->l_next->l_prev = NULL; + return; + } - if ((l->l_prev->l_next = l->l_next) != NULL) - l->l_next->l_prev = l->l_prev; + if ((l->l_prev->l_next = l->l_next) != NULL) + l->l_next->l_prev = l->l_prev; } /* @@ -5775,3 +5780,9 @@ realloc(void *cp, size_t nbytes) return (__crt_realloc(cp, nbytes)); } + +extern int _rtld_version__FreeBSD_version __exported; +int _rtld_version__FreeBSD_version = __FreeBSD_version; + +extern char _rtld_version_laddr_offset __exported; +char _rtld_version_laddr_offset; Modified: stable/12/sys/sys/link_elf.h ============================================================================== --- stable/12/sys/sys/link_elf.h Wed May 27 21:44:26 2020 (r361563) +++ stable/12/sys/sys/link_elf.h Wed May 27 21:56:45 2020 (r361564) @@ -57,13 +57,15 @@ #define LA_SER_SECURE 0x80 /* default (secure) path prepended */ typedef struct link_map { - caddr_t l_addr; /* Base Address of library */ + caddr_t l_base; /* Base Address of library */ #ifdef __mips__ - caddr_t l_offs; /* Load Offset of library */ + caddr_t l_xxx; /* unused */ #endif const char *l_name; /* Absolute Path to Library */ const void *l_ld; /* Pointer to .dynamic in memory */ struct link_map *l_next, *l_prev; /* linked list of of mapped libs */ + caddr_t l_addr; /* Load Offset of library */ + const char *l_refname; /* object we are filtering for */ } Link_map; struct r_debug {
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