Add alignment support to __libc_allocate_tls().
For statically linked binaries, where all relocation are solved by static linker, the linker expect that offset to TLS section is aligned. Additionaly, to maintain absolute alignment, TLS TCB should by also aligned. Obtained from: CheriBSD (initial version) MFC after: 1 month Reviewed by: brooks (previous version), kib Differential Revision: https://reviews.freebsd.org/D12907
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1d909844ab
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=325364
@ -37,9 +37,15 @@
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#include <stdlib.h>
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#include <string.h>
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#include <elf.h>
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#include <unistd.h>
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#include "libc_private.h"
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#define tls_assert(cond) ((cond) ? (void) 0 : \
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(tls_msg(#cond ": assert failed: " __FILE__ ":" \
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__XSTRING(__LINE__) "\n"), abort()))
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#define tls_msg(s) write(STDOUT_FILENO, s, strlen(s))
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/* Provided by jemalloc to avoid bootstrapping issues. */
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void *__je_bootstrap_malloc(size_t size);
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void *__je_bootstrap_calloc(size_t num, size_t size);
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@ -85,6 +91,7 @@ void __libc_free_tls(void *tls, size_t tcbsize, size_t tcbalign);
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static size_t tls_static_space;
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static size_t tls_init_size;
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static size_t tls_init_align;
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static void *tls_init;
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#endif
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@ -109,6 +116,35 @@ __libc_tls_get_addr(void *ti __unused)
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#ifndef PIC
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static void *
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malloc_aligned(size_t size, size_t align)
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{
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void *mem, *res;
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if (align < sizeof(void *))
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align = sizeof(void *);
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mem = __je_bootstrap_malloc(size + sizeof(void *) + align - 1);
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res = (void *)roundup2((uintptr_t)mem + sizeof(void *), align);
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*(void **)((uintptr_t)res - sizeof(void *)) = mem;
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return (res);
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}
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static void
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free_aligned(void *ptr)
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{
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void *mem;
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uintptr_t x;
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if (ptr == NULL)
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return;
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x = (uintptr_t)ptr;
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x -= sizeof(void *);
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mem = *(void **)x;
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__je_bootstrap_free(mem);
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}
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#ifdef TLS_VARIANT_I
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#define TLS_TCB_SIZE (2 * sizeof(void *))
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@ -117,52 +153,63 @@ __libc_tls_get_addr(void *ti __unused)
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* Free Static TLS using the Variant I method.
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*/
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void
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__libc_free_tls(void *tcb, size_t tcbsize, size_t tcbalign __unused)
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__libc_free_tls(void *tcb, size_t tcbsize __unused, size_t tcbalign __unused)
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{
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Elf_Addr *dtv;
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Elf_Addr **tls;
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tls = (Elf_Addr **)((Elf_Addr)tcb + tcbsize - TLS_TCB_SIZE);
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tls = (Elf_Addr **)tcb;
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dtv = tls[0];
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__je_bootstrap_free(dtv);
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__je_bootstrap_free(tcb);
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free_aligned(tls);
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}
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/*
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* Allocate Static TLS using the Variant I method.
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*/
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void *
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__libc_allocate_tls(void *oldtcb, size_t tcbsize, size_t tcbalign __unused)
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__libc_allocate_tls(void *oldtcb, size_t tcbsize, size_t tcbalign)
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{
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Elf_Addr *dtv;
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Elf_Addr **tls;
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char *tcb;
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if (oldtcb != NULL && tcbsize == TLS_TCB_SIZE)
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return (oldtcb);
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tcb = __je_bootstrap_calloc(1, tls_static_space + tcbsize - TLS_TCB_SIZE);
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tls = (Elf_Addr **)(tcb + tcbsize - TLS_TCB_SIZE);
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tls_assert(tcbalign >= TLS_TCB_ALIGN);
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tls_assert(tcbsize == TLS_TCB_SIZE);
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tcbsize = roundup2(tcbsize, tcbalign);
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tls = malloc_aligned(tcbsize + tls_static_space, tcbalign);
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if (tls == NULL) {
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tls_msg("__libc_allocate_tls: Out of memory.\n");
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abort();
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}
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memset(tls, 0, tcbsize + tls_static_space);
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if (oldtcb != NULL) {
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memcpy(tls, oldtcb, tls_static_space);
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memcpy(tls, oldtcb, tcbsize + tls_static_space);
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__je_bootstrap_free(oldtcb);
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/* Adjust the DTV. */
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dtv = tls[0];
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dtv[2] = (Elf_Addr)tls + TLS_TCB_SIZE;
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dtv[2] = (Elf_Addr)tls + tcbsize;
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} else {
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dtv = __je_bootstrap_malloc(3 * sizeof(Elf_Addr));
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if (dtv == NULL) {
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tls_msg("__libc_allocate_tls: Out of memory.\n");
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abort();
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}
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tls[0] = dtv;
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dtv[0] = 1;
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dtv[1] = 1;
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dtv[2] = (Elf_Addr)tls + TLS_TCB_SIZE;
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dtv[0] = 1; /* Generation. */
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dtv[1] = 1; /* Segments count. */
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dtv[2] = (Elf_Addr)tls + tcbsize;
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if (tls_init_size > 0)
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memcpy((void*)dtv[2], tls_init, tls_init_size);
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}
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return(tcb);
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return (tls);
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}
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#endif
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@ -190,7 +237,7 @@ __libc_free_tls(void *tcb, size_t tcbsize __unused, size_t tcbalign)
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dtv = ((Elf_Addr**)tcb)[1];
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tlsend = (Elf_Addr) tcb;
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tlsstart = tlsend - size;
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__je_bootstrap_free((void*) tlsstart);
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free_aligned((void*)tlsstart);
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__je_bootstrap_free(dtv);
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}
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@ -209,8 +256,17 @@ __libc_allocate_tls(void *oldtls, size_t tcbsize, size_t tcbalign)
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if (tcbsize < 2 * sizeof(Elf_Addr))
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tcbsize = 2 * sizeof(Elf_Addr);
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tls = __je_bootstrap_calloc(1, size + tcbsize);
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tls = malloc_aligned(size + tcbsize, tcbalign);
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if (tls == NULL) {
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tls_msg("__libc_allocate_tls: Out of memory.\n");
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abort();
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}
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memset(tls, 0, size + tcbsize);
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dtv = __je_bootstrap_malloc(3 * sizeof(Elf_Addr));
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if (dtv == NULL) {
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tls_msg("__libc_allocate_tls: Out of memory.\n");
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abort();
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}
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segbase = (Elf_Addr)(tls + size);
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((Elf_Addr*)segbase)[0] = segbase;
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@ -305,18 +361,14 @@ _init_tls(void)
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tls_static_space = roundup2(phdr[i].p_memsz,
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phdr[i].p_align);
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tls_init_size = phdr[i].p_filesz;
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tls_init_align = phdr[i].p_align;
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tls_init = (void*) phdr[i].p_vaddr;
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break;
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}
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}
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#ifdef TLS_VARIANT_I
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/*
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* tls_static_space should include space for TLS structure
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*/
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tls_static_space += TLS_TCB_SIZE;
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#endif
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tls = _rtld_allocate_tls(NULL, TLS_TCB_SIZE, TLS_TCB_ALIGN);
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tls = _rtld_allocate_tls(NULL, TLS_TCB_SIZE,
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MAX(TLS_TCB_ALIGN, tls_init_align));
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_set_tp(tls);
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#endif
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