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[PATCH 0/5] add static PIE support for xtensa
by Max Filippov 15 Sep '22

15 Sep '22

Hello, this series does a couple cleanups in the static PIE code and xtensa code and enables static PIE support for the xtensa architecture. Max Filippov (5): static pie: fix building static PDE static pie: replicate PERFORM_BOOTSTRAP_GOT conditions from dl-startup.c xtensa: make GOT protection adjustment conditional xtensa: drop ARCH_NEEDS_BOOTSTRAP_RELOCS xtensa: add static pie support extra/Configs/Config.in | 4 +++- ldso/ldso/xtensa/dl-startup.h | 19 ++++++++++++--- ldso/ldso/xtensa/dl-sysdep.h | 3 --- libc/misc/internals/reloc_static_pie.c | 9 +++++--- libc/sysdeps/linux/xtensa/crt1.S | 27 ++++++++++++++++++++++ libpthread/nptl/sysdeps/generic/libc-tls.c | 7 ++++-- 6 files changed, 57 insertions(+), 12 deletions(-) -- 2.30.2

3 9

[PATCH v2] nptl: use mmap to allocate initial TLS data for static PIE on noMMU
by Max Filippov 07 Sep '22

07 Sep '22

Static PIE ELFs may be loaded on noMMU linux platforms with FDPIC support, but they don't have adjustable brk, and thus cannot allocate memory for the TLS. Use mmap instead of sbrk to allocate initial TLS memory when building with static PIE support for noMMU. Signed-off-by: Max Filippov <jcmvbkbc(a)gmail.com> --- Change v1->v2: - fix typo and add clarification in comment libpthread/nptl/sysdeps/generic/libc-tls.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/libpthread/nptl/sysdeps/generic/libc-tls.c b/libpthread/nptl/sysdeps/generic/libc-tls.c index d9c09fdd6667..7cfe9ac1a85c 100644 --- a/libpthread/nptl/sysdeps/generic/libc-tls.c +++ b/libpthread/nptl/sysdeps/generic/libc-tls.c @@ -169,10 +169,13 @@ __libc_setup_tls (size_t tcbsize, size_t tcbalign) for FDPIC MMU-less platforms: fs/binfmt_elf_fdpic.c: fix brk area overlap with stack on NOMMU https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/fs/b… + Loading static PIE ELFs on noMMU is possible since the linux kernel commit + 1bde925d2354 ("fs/binfmt_elf_fdpic.c: provide NOMMU loader for regular ELF binaries") + and it is subject to the same brk restriction. */ # if defined(TLS_TCB_AT_TP) tcb_offset = roundup (memsz + GL(dl_tls_static_size), tcbalign); -# if defined(__FDPIC__) +# if defined(__FDPIC__) || (!defined(__ARCH_USE_MMU__) && defined(STATIC_PIE)) tlsblock = mmap (NULL, tcb_offset + tcbsize + max_align, PROT_READ|PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); # else @@ -180,7 +183,7 @@ __libc_setup_tls (size_t tcbsize, size_t tcbalign) # endif # elif defined(TLS_DTV_AT_TP) tcb_offset = roundup (tcbsize, align ?: 1); -# if defined(__FDPIC__) +# if defined(__FDPIC__) || (!defined(__ARCH_USE_MMU__) && defined(STATIC_PIE)) tlsblock = mmap (NULL, tcb_offset + memsz + max_align + TLS_PRE_TCB_SIZE + GL(dl_tls_static_size), PROT_READ|PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); # else -- 2.30.2

2 1

[PATCH v3] Static PIE support for mips
by linted 07 Sep '22

07 Sep '22

Hello, This is a slight update to the v2 patch. I realized that I left some extraneous comments in crt1.S. This patch removes those comments. -------- From f5a4f77a396631bfceea2967b6a9100b09802f6c Mon Sep 17 00:00:00 2001 From: linted <linted(a)users.noreply.github.com> Date: Sat, 20 Aug 2022 16:41:38 -0400 Subject: [PATCH] Added support for creation of Static Position-Independent Executables (PIE) on mips Updated config to allow compilation of rcrt1.o for mips and modified it's crt1.S to perform relocates in __start. The mips architecture performs relocations differently then most other architectures. reloc_static_pie was rewritten, taking code from dl-startup.c, in order to perfrom the additional relocations. Modifications were made to mips' dl-startup.h to allow for the use of contained macros without including _start definition. Signed-off-by: linted <linted(a)users.noreply.github.com> --- extra/Configs/Config.in | 2 +- ldso/ldso/mips/dl-startup.h | 3 +- libc/misc/internals/Makefile.in | 2 +- libc/misc/internals/reloc_static_pie.c | 93 +++++++++++++++++++++----- libc/sysdeps/linux/mips/crt1.S | 23 +++++++ 5 files changed, 105 insertions(+), 18 deletions(-) diff --git a/extra/Configs/Config.in b/extra/Configs/Config.in index e0905e956..43c04fd0a 100644 --- a/extra/Configs/Config.in +++ b/extra/Configs/Config.in @@ -324,7 +324,7 @@ config DOPIC config STATIC_PIE bool "Add support for Static Position Independent Executables (PIE)" default n - depends on DOPIC && !UCLIBC_FORMAT_FDPIC_ELF && (TARGET_arm || TARGET_i386 || TARGET_x86_64 || TARGET_aarch64) + depends on DOPIC && !UCLIBC_FORMAT_FDPIC_ELF && (TARGET_arm || TARGET_i386 || TARGET_x86_64 || TARGET_aarch64 || TARGET_mips) config ARCH_HAS_NO_SHARED bool diff --git a/ldso/ldso/mips/dl-startup.h b/ldso/ldso/mips/dl-startup.h index 8026f1702..c2168d774 100644 --- a/ldso/ldso/mips/dl-startup.h +++ b/ldso/ldso/mips/dl-startup.h @@ -7,6 +7,7 @@ #include <sgidefs.h> +#ifndef L_rcrt1 __asm__("" " .text\n" " .globl _start\n" @@ -114,6 +115,7 @@ __asm__("" "\n\n" ".previous\n" ); +#endif /* * Get a pointer to the argv array. On many platforms this can be just @@ -191,6 +193,5 @@ do { \ case R_MIPS_NONE: \ break; \ default: \ - SEND_STDERR("Aiieeee!"); \ _dl_exit(1); \ } diff --git a/libc/misc/internals/Makefile.in b/libc/misc/internals/Makefile.in index 69af8b76e..908b18321 100644 --- a/libc/misc/internals/Makefile.in +++ b/libc/misc/internals/Makefile.in @@ -17,7 +17,7 @@ MISC_INTERNALS_SRC := $(patsubst %.c,$(MISC_INTERNALS_DIR)/%.c,$(CSRC-y)) MISC_INTERNALS_OBJ := $(patsubst %.c,$(MISC_INTERNALS_OUT)/%.o,$(CSRC-y)) CFLAGS-__uClibc_main.c := $(SSP_DISABLE_FLAGS) -CFLAGS-reloc_static_pie.c := $(SSP_DISABLE_FLAGS) +CFLAGS-reloc_static_pie.c := $(SSP_DISABLE_FLAGS) -DL_rcrt1 libc-y += $(MISC_INTERNALS_OBJ) ifneq ($(UCLIBC_FORMAT_SHARED_FLAT),y) diff --git a/libc/misc/internals/reloc_static_pie.c b/libc/misc/internals/reloc_static_pie.c index 578202d23..c0027de6f 100644 --- a/libc/misc/internals/reloc_static_pie.c +++ b/libc/misc/internals/reloc_static_pie.c @@ -15,33 +15,96 @@ You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, see <https://www.gnu.org/licenses/>. */ - +#define IS_IN_rtld // force inline function calls #include <link.h> #include <elf.h> #include <dl-elf.h> +#include <ldso.h> +#ifdef __mips__ +#include <dl-startup.h> +#endif + ElfW(Addr) _dl_load_base = NULL; void reloc_static_pie (ElfW(Addr) load_addr); void -reloc_static_pie (ElfW(Addr) load_addr) +reloc_static_pie(ElfW(Addr) load_addr) { - ElfW(Word) relative_count = 0; - ElfW(Addr) rel_addr = 0; - ElfW(Dyn) * dyn_addr = NULL; - unsigned long dynamic_info[DYNAMIC_SIZE] = {0}; + int indx; + ElfW(Addr) got; + ElfW(Dyn) *dpnt; + struct elf_resolve tpnt_tmp; + struct elf_resolve *tpnt = &tpnt_tmp; + + DL_BOOT_COMPUTE_GOT(got); + DL_BOOT_COMPUTE_DYN(dpnt, got, (DL_LOADADDR_TYPE)load_addr); + + _dl_memset(tpnt, 0, sizeof(struct elf_resolve)); + tpnt->loadaddr = load_addr; + tpnt->dynamic_addr = dpnt; + + __dl_parse_dynamic_info(dpnt, tpnt->dynamic_info, NULL, load_addr); + +#if defined(PERFORM_BOOTSTRAP_GOT) + /* some arches (like MIPS) we have to tweak the GOT before relocations */ + PERFORM_BOOTSTRAP_GOT(tpnt); +#endif + + +#if defined(ELF_MACHINE_PLTREL_OVERLAP) +# define INDX_MAX 1 +#else +# define INDX_MAX 2 +#endif + + for (indx = 0; indx < INDX_MAX; indx++) { + unsigned long rel_addr, rel_size; + ElfW(Word) relative_count = tpnt->dynamic_info[DT_RELCONT_IDX]; + + rel_addr = (indx ? tpnt->dynamic_info[DT_JMPREL] : + tpnt->dynamic_info[DT_RELOC_TABLE_ADDR]); + rel_size = (indx ? tpnt->dynamic_info[DT_PLTRELSZ] : + tpnt->dynamic_info[DT_RELOC_TABLE_SIZE]); + + if (!rel_addr) + continue; - /* Read our own dynamic section and fill in the info array. */ - dyn_addr = ((void *) load_addr + elf_machine_dynamic ()); + if((0 == indx) && relative_count) { + rel_size -= relative_count * sizeof(ELF_RELOC); + elf_machine_relative(load_addr, rel_addr, relative_count); + rel_addr += relative_count * sizeof(ELF_RELOC); + } - /* Use the underlying function to avoid TLS access before initialization */ - __dl_parse_dynamic_info(dyn_addr, dynamic_info, NULL, load_addr); +#ifdef ARCH_NEEDS_BOOTSTRAP_RELOCS + { + ELF_RELOC *rpnt; + unsigned int i; + ElfW(Sym) *sym; + unsigned long symbol_addr; + int symtab_index; + unsigned long *reloc_addr; - /* Perform relocations */ - relative_count = dynamic_info[DT_RELCONT_IDX]; - rel_addr = dynamic_info[DT_RELOC_TABLE_ADDR]; - elf_machine_relative(load_addr, rel_addr, relative_count); + /* Now parse the relocation information */ + rpnt = (ELF_RELOC *) rel_addr; + for (i = 0; i < rel_size; i += sizeof(ELF_RELOC), rpnt++) { + reloc_addr = (unsigned long *) DL_RELOC_ADDR(load_addr, (unsigned long)rpnt->r_offset); + symtab_index = ELF_R_SYM(rpnt->r_info); + symbol_addr = 0; + sym = NULL; + if (symtab_index) { + ElfW(Sym) *symtab; + symtab = (ElfW(Sym) *) tpnt->dynamic_info[DT_SYMTAB]; + sym = &symtab[symtab_index]; + symbol_addr = (unsigned long) DL_RELOC_ADDR(load_addr, sym->st_value); + } + /* Use this machine-specific macro to perform the actual relocation. */ + PERFORM_BOOTSTRAP_RELOC(rpnt, reloc_addr, symbol_addr, load_addr, sym); + } + } +#endif + } _dl_load_base = load_addr; -} +} \ No newline at end of file diff --git a/libc/sysdeps/linux/mips/crt1.S b/libc/sysdeps/linux/mips/crt1.S index 083615515..7c4db447c 100644 --- a/libc/sysdeps/linux/mips/crt1.S +++ b/libc/sysdeps/linux/mips/crt1.S @@ -77,6 +77,10 @@ #ifndef __UCLIBC_CTOR_DTOR__ .weak _init .weak _fini +#endif +#ifdef L_rcrt1 + .type reloc_static_pie,@function + .hidden .L0 #endif .type main,@function .type __uClibc_main,@function @@ -89,6 +93,25 @@ __start: #else PTR_LA $28, _gp /* Setup GP correctly if we're non-PIC. */ move $31, $0 +#endif +#ifdef L_rcrt1 + PTR_LA $4, _DYNAMIC /* Place _DYNAMIC into the GOT */ + REG_S $4, -0x7ff0($28) /* offset to GOT stolen from dl-startup */ + jal .L0 /* Get the current $pc address */ +.L0: + PTR_SUBU $4, $31, $25 /* Calculate load addr */ + move $31, $0 /* Clear ra */ + and $29, -2 * SZREG /* Ensure stack is aligned */ + PTR_ADDIU $29, (-2 * SZREG) /* Allocate 2 register spaces on stack */ + REG_S $2, SZREG($29) /* Store atexit in case it exists */ + PTR_LA $5, reloc_static_pie /* function calls before relocation + don't work unless we set $t9 manually */ + PTR_ADDU $25, $4, $5 /* store reloc_static_pie in $t9 */ + jalr $25 /* call reloc_static_pie */ + nop /* delay slot, just in case */ + REG_L $2, SZREG($29) /* cleanup stack */ + PTR_ADDIU $29, $29, (2 * SZREG) + #endif PTR_LA $4, main /* main */ -- 2.34.1

3 2

[PATCH] nptl: use mmap to allocate initial TLS data for static PIE on noMMU
by Max Filippov 06 Sep '22

06 Sep '22

Static PIE ELFs may be loaded on noMMU linux platforms with FDPIC support, but they don't have adjustable brk, and thus cannot allocate memory for the TLS. Use mmap instead of sbrk to allocate initial TLS memory when building with static PIE support for noMMU. Signed-off-by: Max Filippov <jcmvbkbc(a)gmail.com> --- libpthread/nptl/sysdeps/generic/libc-tls.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/libpthread/nptl/sysdeps/generic/libc-tls.c b/libpthread/nptl/sysdeps/generic/libc-tls.c index d9c09fdd6667..374ba2a48620 100644 --- a/libpthread/nptl/sysdeps/generic/libc-tls.c +++ b/libpthread/nptl/sysdeps/generic/libc-tls.c @@ -169,10 +169,13 @@ __libc_setup_tls (size_t tcbsize, size_t tcbalign) for FDPIC MMU-less platforms: fs/binfmt_elf_fdpic.c: fix brk area overlap with stack on NOMMU https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/fs/b… + Loading static PIE ELFs is possible since linux kernel commit + 1bde925d2354 ("fs/binfmt_elf_fdpic.c: provide NOMMU loader for regular ELF binaries") + and it is subject to the same brk restrixtion. */ # if defined(TLS_TCB_AT_TP) tcb_offset = roundup (memsz + GL(dl_tls_static_size), tcbalign); -# if defined(__FDPIC__) +# if defined(__FDPIC__) || (!defined(__ARCH_USE_MMU__) && defined(STATIC_PIE)) tlsblock = mmap (NULL, tcb_offset + tcbsize + max_align, PROT_READ|PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); # else @@ -180,7 +183,7 @@ __libc_setup_tls (size_t tcbsize, size_t tcbalign) # endif # elif defined(TLS_DTV_AT_TP) tcb_offset = roundup (tcbsize, align ?: 1); -# if defined(__FDPIC__) +# if defined(__FDPIC__) || (!defined(__ARCH_USE_MMU__) && defined(STATIC_PIE)) tlsblock = mmap (NULL, tcb_offset + memsz + max_align + TLS_PRE_TCB_SIZE + GL(dl_tls_static_size), PROT_READ|PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); # else -- 2.30.2

1 0

[Patch] Static PIE support for mips
by linted 02 Sep '22

02 Sep '22

Hello, I have completed a patch to get static pie support working for the mips architecture. Unfortunately a lot of the optimizations I made for previous architectures needed to be rewritten in order to support the way that mips works. There is a substantial rewrite of reloc_static_pie, however the code is nearly a copy paste from dl-startup.c and has been tested with all the currently supported architectures to ensure that it still works. In order to compile with gcc, a patch for mips static pie is required. I'm actively working on submitting said patch, but I do not have a link for it yet. In the meantime, compilation using the following flags passed to gcc should suffice. mips-linux-gcc -static-pie -Bstatic -pie --no-dynamic-linker -z text input.c -o output ---- From a6fa331c7ea16b5146c0d3ba3b2d6d723f09a9b4 Mon Sep 17 00:00:00 2001 From: linted <linted(a)users.noreply.github.com> Date: Sat, 20 Aug 2022 16:41:38 -0400 Subject: [PATCH] Added support for creation of Static Position-Independent Executables (PIE) on mips Updated config to allow compilation of rcrt1.o for mips and modified it's crt1.S to perform relocates in __start. The mips architecture performs relocations differently then most other architectures. reloc_static_pie was rewritten, taking code from dl-startup.c, in order to perform the additional relocations. Modifications were made to mips' dl-startup.h to allow for the use of contained macros without including _start definition. Signed-off-by: linted <linted(a)users.noreply.github.com> --- extra/Configs/Config.in | 2 +- ldso/ldso/mips/dl-startup.h | 3 +- libc/misc/internals/Makefile.in | 2 +- libc/misc/internals/reloc_static_pie.c | 91 ++++++++++++++++++++++---- libc/sysdeps/linux/mips/crt1.S | 22 +++++++ 5 files changed, 103 insertions(+), 17 deletions(-) diff --git a/extra/Configs/Config.in b/extra/Configs/Config.in index e0905e956..43c04fd0a 100644 --- a/extra/Configs/Config.in +++ b/extra/Configs/Config.in @@ -324,7 +324,7 @@ config DOPIC config STATIC_PIE bool "Add support for Static Position Independent Executables (PIE)" default n - depends on DOPIC && !UCLIBC_FORMAT_FDPIC_ELF && (TARGET_arm || TARGET_i386 || TARGET_x86_64 || TARGET_aarch64) + depends on DOPIC && !UCLIBC_FORMAT_FDPIC_ELF && (TARGET_arm || TARGET_i386 || TARGET_x86_64 || TARGET_aarch64 || TARGET_mips) config ARCH_HAS_NO_SHARED bool diff --git a/ldso/ldso/mips/dl-startup.h b/ldso/ldso/mips/dl-startup.h index 8026f1702..c2168d774 100644 --- a/ldso/ldso/mips/dl-startup.h +++ b/ldso/ldso/mips/dl-startup.h @@ -7,6 +7,7 @@ #include <sgidefs.h> +#ifndef L_rcrt1 __asm__("" " .text\n" " .globl _start\n" @@ -114,6 +115,7 @@ __asm__("" "\n\n" ".previous\n" ); +#endif /* * Get a pointer to the argv array. On many platforms this can be just @@ -191,6 +193,5 @@ do { \ case R_MIPS_NONE: \ break; \ default: \ - SEND_STDERR("Aiieeee!"); \ _dl_exit(1); \ } diff --git a/libc/misc/internals/Makefile.in b/libc/misc/internals/Makefile.in index 69af8b76e..908b18321 100644 --- a/libc/misc/internals/Makefile.in +++ b/libc/misc/internals/Makefile.in @@ -17,7 +17,7 @@ MISC_INTERNALS_SRC := $(patsubst %.c,$(MISC_INTERNALS_DIR)/%.c,$(CSRC-y)) MISC_INTERNALS_OBJ := $(patsubst %.c,$(MISC_INTERNALS_OUT)/%.o,$(CSRC-y)) CFLAGS-__uClibc_main.c := $(SSP_DISABLE_FLAGS) -CFLAGS-reloc_static_pie.c := $(SSP_DISABLE_FLAGS) +CFLAGS-reloc_static_pie.c := $(SSP_DISABLE_FLAGS) -DL_rcrt1 libc-y += $(MISC_INTERNALS_OBJ) ifneq ($(UCLIBC_FORMAT_SHARED_FLAT),y) diff --git a/libc/misc/internals/reloc_static_pie.c b/libc/misc/internals/reloc_static_pie.c index 578202d23..cd9190d60 100644 --- a/libc/misc/internals/reloc_static_pie.c +++ b/libc/misc/internals/reloc_static_pie.c @@ -20,28 +20,91 @@ #include <elf.h> #include <dl-elf.h> +#include <ldso.h> +#ifdef __mips__ +#include <dl-startup.h> +#endif + ElfW(Addr) _dl_load_base = NULL; void reloc_static_pie (ElfW(Addr) load_addr); void -reloc_static_pie (ElfW(Addr) load_addr) +reloc_static_pie(ElfW(Addr) load_addr) { - ElfW(Word) relative_count = 0; - ElfW(Addr) rel_addr = 0; - ElfW(Dyn) * dyn_addr = NULL; - unsigned long dynamic_info[DYNAMIC_SIZE] = {0}; + int indx; + ElfW(Addr) got; + ElfW(Dyn) *dpnt; + struct elf_resolve tpnt_tmp; + struct elf_resolve *tpnt = &tpnt_tmp; + + DL_BOOT_COMPUTE_GOT(got); + DL_BOOT_COMPUTE_DYN(dpnt, got, (DL_LOADADDR_TYPE)load_addr); + + _dl_memset(tpnt, 0, sizeof(struct elf_resolve)); + tpnt->loadaddr = load_addr; + tpnt->dynamic_addr = dpnt; + + __dl_parse_dynamic_info(dpnt, tpnt->dynamic_info, NULL, load_addr); + +#if defined(PERFORM_BOOTSTRAP_GOT) + /* some arches (like MIPS) we have to tweak the GOT before relocations */ + PERFORM_BOOTSTRAP_GOT(tpnt); +#endif + + +#if defined(ELF_MACHINE_PLTREL_OVERLAP) +# define INDX_MAX 1 +#else +# define INDX_MAX 2 +#endif + + for (indx = 0; indx < INDX_MAX; indx++) { + unsigned long rel_addr, rel_size; + ElfW(Word) relative_count = tpnt->dynamic_info[DT_RELCONT_IDX]; + + rel_addr = (indx ? tpnt->dynamic_info[DT_JMPREL] : + tpnt->dynamic_info[DT_RELOC_TABLE_ADDR]); + rel_size = (indx ? tpnt->dynamic_info[DT_PLTRELSZ] : + tpnt->dynamic_info[DT_RELOC_TABLE_SIZE]); + + if (!rel_addr) + continue; - /* Read our own dynamic section and fill in the info array. */ - dyn_addr = ((void *) load_addr + elf_machine_dynamic ()); + if((0 == indx) && relative_count) { + rel_size -= relative_count * sizeof(ELF_RELOC); + elf_machine_relative(load_addr, rel_addr, relative_count); + rel_addr += relative_count * sizeof(ELF_RELOC); + } - /* Use the underlying function to avoid TLS access before initialization */ - __dl_parse_dynamic_info(dyn_addr, dynamic_info, NULL, load_addr); +#ifdef ARCH_NEEDS_BOOTSTRAP_RELOCS + { + ELF_RELOC *rpnt; + unsigned int i; + ElfW(Sym) *sym; + unsigned long symbol_addr; + int symtab_index; + unsigned long *reloc_addr; - /* Perform relocations */ - relative_count = dynamic_info[DT_RELCONT_IDX]; - rel_addr = dynamic_info[DT_RELOC_TABLE_ADDR]; - elf_machine_relative(load_addr, rel_addr, relative_count); + /* Now parse the relocation information */ + rpnt = (ELF_RELOC *) rel_addr; + for (i = 0; i < rel_size; i += sizeof(ELF_RELOC), rpnt++) { + reloc_addr = (unsigned long *) DL_RELOC_ADDR(load_addr, (unsigned long)rpnt->r_offset); + symtab_index = ELF_R_SYM(rpnt->r_info); + symbol_addr = 0; + sym = NULL; + if (symtab_index) { + ElfW(Sym) *symtab; + symtab = (ElfW(Sym) *) tpnt->dynamic_info[DT_SYMTAB]; + sym = &symtab[symtab_index]; + symbol_addr = (unsigned long) DL_RELOC_ADDR(load_addr, sym->st_value); + } + /* Use this machine-specific macro to perform the actual relocation. */ + PERFORM_BOOTSTRAP_RELOC(rpnt, reloc_addr, symbol_addr, load_addr, sym); + } + } +#endif + } _dl_load_base = load_addr; -} +} \ No newline at end of file diff --git a/libc/sysdeps/linux/mips/crt1.S b/libc/sysdeps/linux/mips/crt1.S index 083615515..a7f72a90f 100644 --- a/libc/sysdeps/linux/mips/crt1.S +++ b/libc/sysdeps/linux/mips/crt1.S @@ -77,6 +77,10 @@ #ifndef __UCLIBC_CTOR_DTOR__ .weak _init .weak _fini +#endif +#ifdef L_rcrt1 + .type reloc_static_pie,@function + .weak reloc_static_pie #endif .type main,@function .type __uClibc_main,@function @@ -90,6 +94,24 @@ __start: PTR_LA $28, _gp /* Setup GP correctly if we're non-PIC. */ move $31, $0 #endif +#ifdef L_rcrt1 + PTR_LA $4, _DYNAMIC /* Place _DYNAMIC into the GOT */ + REG_S $4, -0x7ff0($28) + jal L0 /* Get the current $pc address */ +L0: + INT_SUB $25, $31, $25 /* Calculate load addr */ + move $4, $25 /* store load addr in param 1 */ + and $29, -2 * SZREG /* Ensure stack is aligned */ + addi $29, $29, (-2 * SZREG) /* Allocate 2 register spaces on stack */ + REG_S $2, SZREG($29) /* Store atexit in case it exists */ + PTR_LA $5, reloc_static_pie /* function calls before relocation + don't work unless we set $t9 manually */ + INT_ADDU $25, $25, $5 /* store reloc_static_pie in $t9 */ + bal reloc_static_pie /* call, and pray the compiler adds a nop + in delay slot */ + REG_L $2, SZREG($29) /* cleanup stack */ + addi $29, $29, (2 * SZREG) +#endif PTR_LA $4, main /* main */ PTR_L $5, 0($29) /* argc */ -- 2.34.1

2 6

[PATCH v2] static pie: fix building static PDE
by Max Filippov 02 Sep '22

02 Sep '22

When uclibc is built with static PIE support the _dl_load_base variable shared between the libc-tls.c and reloc_static_pie.c creates the dependency that requires linking reloc_static_pie.o into static position-dependent executables resulting in the following build errors: gcc -static test.c -o test ...ld: ...usr/lib/libc.a(reloc_static_pie.os):(.text+0x0): undefined reference to `_DYNAMIC' Move _dl_load_base definition to libc-tls.c to resolve this dependency and fix static PDE build. Signed-off-by: Max Filippov <jcmvbkbc(a)gmail.com> --- Changes v1->v2: - make _dl_load_base definition conditional libc/misc/internals/reloc_static_pie.c | 2 +- libpthread/nptl/sysdeps/generic/libc-tls.c | 7 +++++-- 2 files changed, 6 insertions(+), 3 deletions(-) diff --git a/libc/misc/internals/reloc_static_pie.c b/libc/misc/internals/reloc_static_pie.c index 578202d235a1..f66f7a4236c9 100644 --- a/libc/misc/internals/reloc_static_pie.c +++ b/libc/misc/internals/reloc_static_pie.c @@ -20,7 +20,7 @@ #include <elf.h> #include <dl-elf.h> -ElfW(Addr) _dl_load_base = NULL; +extern ElfW(Addr) _dl_load_base; void reloc_static_pie (ElfW(Addr) load_addr); diff --git a/libpthread/nptl/sysdeps/generic/libc-tls.c b/libpthread/nptl/sysdeps/generic/libc-tls.c index 0c8c558d05d3..d9c09fdd6667 100644 --- a/libpthread/nptl/sysdeps/generic/libc-tls.c +++ b/libpthread/nptl/sysdeps/generic/libc-tls.c @@ -117,6 +117,10 @@ init_static_tls (size_t memsz, size_t align) GL(dl_tls_static_nelem) = GL(dl_tls_max_dtv_idx); } +#if !defined(__FDPIC__) && !defined(SHARED) && defined(STATIC_PIE) +ElfW(Addr) _dl_load_base; +#endif + void __libc_setup_tls (size_t tcbsize, size_t tcbalign); void __libc_setup_tls (size_t tcbsize, size_t tcbalign) @@ -143,8 +147,7 @@ __libc_setup_tls (size_t tcbsize, size_t tcbalign) #else initimage = (void *) phdr->p_vaddr; #if !defined(SHARED) && defined(STATIC_PIE) - extern ElfW(Addr) _dl_load_base; - initimage += _dl_load_base; + initimage += _dl_load_base; #endif #endif align = phdr->p_align; -- 2.30.2

2 1

[PATCH] static pie: fix building static PDE
by Max Filippov 02 Sep '22

02 Sep '22

When uclibc is built with static PIE support the _dl_load_base variable shared between the libc-tls.c and reloc_static_pie.c creates the dependency that requires linking reloc_static_pie.o into static position-dependent executables resulting in the following build errors: gcc -static test.c -o test ...ld: ...usr/lib/libc.a(reloc_static_pie.os):(.text+0x0): undefined reference to `_DYNAMIC' Move _dl_load_base definition to libc-tls.c to resolve this dependency and fix static PDE build. Signed-off-by: Max Filippov <jcmvbkbc(a)gmail.com> --- libc/misc/internals/reloc_static_pie.c | 2 +- libpthread/nptl/sysdeps/generic/libc-tls.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/libc/misc/internals/reloc_static_pie.c b/libc/misc/internals/reloc_static_pie.c index 578202d235a1..f66f7a4236c9 100644 --- a/libc/misc/internals/reloc_static_pie.c +++ b/libc/misc/internals/reloc_static_pie.c @@ -20,7 +20,7 @@ #include <elf.h> #include <dl-elf.h> -ElfW(Addr) _dl_load_base = NULL; +extern ElfW(Addr) _dl_load_base; void reloc_static_pie (ElfW(Addr) load_addr); diff --git a/libpthread/nptl/sysdeps/generic/libc-tls.c b/libpthread/nptl/sysdeps/generic/libc-tls.c index 0c8c558d05d3..e0e272e01dae 100644 --- a/libpthread/nptl/sysdeps/generic/libc-tls.c +++ b/libpthread/nptl/sysdeps/generic/libc-tls.c @@ -117,6 +117,7 @@ init_static_tls (size_t memsz, size_t align) GL(dl_tls_static_nelem) = GL(dl_tls_max_dtv_idx); } +ElfW(Addr) _dl_load_base; void __libc_setup_tls (size_t tcbsize, size_t tcbalign); void __libc_setup_tls (size_t tcbsize, size_t tcbalign) @@ -143,8 +144,7 @@ __libc_setup_tls (size_t tcbsize, size_t tcbalign) #else initimage = (void *) phdr->p_vaddr; #if !defined(SHARED) && defined(STATIC_PIE) - extern ElfW(Addr) _dl_load_base; - initimage += _dl_load_base; + initimage += _dl_load_base; #endif #endif align = phdr->p_align; -- 2.30.2

2 2

[PATCH v2] Static PIE support for mips
by linted 01 Sep '22

01 Sep '22

Hello, This is the second iteration of the patch for mips static pie support. This version fixes two truncation errors which were occurring. The first problem came from calling reloc_static_pie() directly from __start which caused gcc to request a R_MIPS_PC16 relocation. Unfortunately that type of relocation would not be large enough for the linker to place the PC relative address if the supplied user code was too large. By changing the call to be a register relative jump which we were already correctly calculating, the problem went away. The other bug was the improper usage of the mips assembly macros. I had chosen to use INT_* functions for the calculation to determine the load address. These macros ended up truncating the results since they can use the 32bit instructions on mips64. This was remedied by changing to PTR_* macros. ------- From 051a7536e8f3bfb96c290bda74749886ae7d1693 Mon Sep 17 00:00:00 2001 From: linted <linted(a)users.noreply.github.com> Date: Sat, 20 Aug 2022 16:41:38 -0400 Subject: [PATCH] Added support for creation of Static Position-Independent Executables (PIE) on mips Updated config to allow compilation of rcrt1.o for mips and modified it's crt1.S to perform relocates in __start. The mips architecture performs relocations differently then most other architectures. reloc_static_pie was rewritten, taking code from dl-startup.c, in order to perfrom the additional relocations. Modifications were made to mips' dl-startup.h to allow for the use of contained macros without including _start definition. Signed-off-by: linted <linted(a)users.noreply.github.com> --- extra/Configs/Config.in | 2 +- ldso/ldso/mips/dl-startup.h | 3 +- libc/misc/internals/Makefile.in | 2 +- libc/misc/internals/reloc_static_pie.c | 93 +++++++++++++++++++++----- libc/sysdeps/linux/mips/crt1.S | 29 ++++++++ 5 files changed, 111 insertions(+), 18 deletions(-) diff --git a/extra/Configs/Config.in b/extra/Configs/Config.in index e0905e956..43c04fd0a 100644 --- a/extra/Configs/Config.in +++ b/extra/Configs/Config.in @@ -324,7 +324,7 @@ config DOPIC config STATIC_PIE bool "Add support for Static Position Independent Executables (PIE)" default n - depends on DOPIC && !UCLIBC_FORMAT_FDPIC_ELF && (TARGET_arm || TARGET_i386 || TARGET_x86_64 || TARGET_aarch64) + depends on DOPIC && !UCLIBC_FORMAT_FDPIC_ELF && (TARGET_arm || TARGET_i386 || TARGET_x86_64 || TARGET_aarch64 || TARGET_mips) config ARCH_HAS_NO_SHARED bool diff --git a/ldso/ldso/mips/dl-startup.h b/ldso/ldso/mips/dl-startup.h index 8026f1702..c2168d774 100644 --- a/ldso/ldso/mips/dl-startup.h +++ b/ldso/ldso/mips/dl-startup.h @@ -7,6 +7,7 @@ #include <sgidefs.h> +#ifndef L_rcrt1 __asm__("" " .text\n" " .globl _start\n" @@ -114,6 +115,7 @@ __asm__("" "\n\n" ".previous\n" ); +#endif /* * Get a pointer to the argv array. On many platforms this can be just @@ -191,6 +193,5 @@ do { \ case R_MIPS_NONE: \ break; \ default: \ - SEND_STDERR("Aiieeee!"); \ _dl_exit(1); \ } diff --git a/libc/misc/internals/Makefile.in b/libc/misc/internals/Makefile.in index 69af8b76e..908b18321 100644 --- a/libc/misc/internals/Makefile.in +++ b/libc/misc/internals/Makefile.in @@ -17,7 +17,7 @@ MISC_INTERNALS_SRC := $(patsubst %.c,$(MISC_INTERNALS_DIR)/%.c,$(CSRC-y)) MISC_INTERNALS_OBJ := $(patsubst %.c,$(MISC_INTERNALS_OUT)/%.o,$(CSRC-y)) CFLAGS-__uClibc_main.c := $(SSP_DISABLE_FLAGS) -CFLAGS-reloc_static_pie.c := $(SSP_DISABLE_FLAGS) +CFLAGS-reloc_static_pie.c := $(SSP_DISABLE_FLAGS) -DL_rcrt1 libc-y += $(MISC_INTERNALS_OBJ) ifneq ($(UCLIBC_FORMAT_SHARED_FLAT),y) diff --git a/libc/misc/internals/reloc_static_pie.c b/libc/misc/internals/reloc_static_pie.c index 578202d23..c0027de6f 100644 --- a/libc/misc/internals/reloc_static_pie.c +++ b/libc/misc/internals/reloc_static_pie.c @@ -15,33 +15,96 @@ You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, see <https://www.gnu.org/licenses/>. */ - +#define IS_IN_rtld // force inline function calls #include <link.h> #include <elf.h> #include <dl-elf.h> +#include <ldso.h> +#ifdef __mips__ +#include <dl-startup.h> +#endif + ElfW(Addr) _dl_load_base = NULL; void reloc_static_pie (ElfW(Addr) load_addr); void -reloc_static_pie (ElfW(Addr) load_addr) +reloc_static_pie(ElfW(Addr) load_addr) { - ElfW(Word) relative_count = 0; - ElfW(Addr) rel_addr = 0; - ElfW(Dyn) * dyn_addr = NULL; - unsigned long dynamic_info[DYNAMIC_SIZE] = {0}; + int indx; + ElfW(Addr) got; + ElfW(Dyn) *dpnt; + struct elf_resolve tpnt_tmp; + struct elf_resolve *tpnt = &tpnt_tmp; + + DL_BOOT_COMPUTE_GOT(got); + DL_BOOT_COMPUTE_DYN(dpnt, got, (DL_LOADADDR_TYPE)load_addr); + + _dl_memset(tpnt, 0, sizeof(struct elf_resolve)); + tpnt->loadaddr = load_addr; + tpnt->dynamic_addr = dpnt; + + __dl_parse_dynamic_info(dpnt, tpnt->dynamic_info, NULL, load_addr); + +#if defined(PERFORM_BOOTSTRAP_GOT) + /* some arches (like MIPS) we have to tweak the GOT before relocations */ + PERFORM_BOOTSTRAP_GOT(tpnt); +#endif + + +#if defined(ELF_MACHINE_PLTREL_OVERLAP) +# define INDX_MAX 1 +#else +# define INDX_MAX 2 +#endif + + for (indx = 0; indx < INDX_MAX; indx++) { + unsigned long rel_addr, rel_size; + ElfW(Word) relative_count = tpnt->dynamic_info[DT_RELCONT_IDX]; + + rel_addr = (indx ? tpnt->dynamic_info[DT_JMPREL] : + tpnt->dynamic_info[DT_RELOC_TABLE_ADDR]); + rel_size = (indx ? tpnt->dynamic_info[DT_PLTRELSZ] : + tpnt->dynamic_info[DT_RELOC_TABLE_SIZE]); + + if (!rel_addr) + continue; - /* Read our own dynamic section and fill in the info array. */ - dyn_addr = ((void *) load_addr + elf_machine_dynamic ()); + if((0 == indx) && relative_count) { + rel_size -= relative_count * sizeof(ELF_RELOC); + elf_machine_relative(load_addr, rel_addr, relative_count); + rel_addr += relative_count * sizeof(ELF_RELOC); + } - /* Use the underlying function to avoid TLS access before initialization */ - __dl_parse_dynamic_info(dyn_addr, dynamic_info, NULL, load_addr); +#ifdef ARCH_NEEDS_BOOTSTRAP_RELOCS + { + ELF_RELOC *rpnt; + unsigned int i; + ElfW(Sym) *sym; + unsigned long symbol_addr; + int symtab_index; + unsigned long *reloc_addr; - /* Perform relocations */ - relative_count = dynamic_info[DT_RELCONT_IDX]; - rel_addr = dynamic_info[DT_RELOC_TABLE_ADDR]; - elf_machine_relative(load_addr, rel_addr, relative_count); + /* Now parse the relocation information */ + rpnt = (ELF_RELOC *) rel_addr; + for (i = 0; i < rel_size; i += sizeof(ELF_RELOC), rpnt++) { + reloc_addr = (unsigned long *) DL_RELOC_ADDR(load_addr, (unsigned long)rpnt->r_offset); + symtab_index = ELF_R_SYM(rpnt->r_info); + symbol_addr = 0; + sym = NULL; + if (symtab_index) { + ElfW(Sym) *symtab; + symtab = (ElfW(Sym) *) tpnt->dynamic_info[DT_SYMTAB]; + sym = &symtab[symtab_index]; + symbol_addr = (unsigned long) DL_RELOC_ADDR(load_addr, sym->st_value); + } + /* Use this machine-specific macro to perform the actual relocation. */ + PERFORM_BOOTSTRAP_RELOC(rpnt, reloc_addr, symbol_addr, load_addr, sym); + } + } +#endif + } _dl_load_base = load_addr; -} +} \ No newline at end of file diff --git a/libc/sysdeps/linux/mips/crt1.S b/libc/sysdeps/linux/mips/crt1.S index 083615515..6a4257b1f 100644 --- a/libc/sysdeps/linux/mips/crt1.S +++ b/libc/sysdeps/linux/mips/crt1.S @@ -77,6 +77,10 @@ #ifndef __UCLIBC_CTOR_DTOR__ .weak _init .weak _fini +#endif +#ifdef L_rcrt1 + .type reloc_static_pie,@function + .hidden .L0 #endif .type main,@function .type __uClibc_main,@function @@ -89,6 +93,31 @@ __start: #else PTR_LA $28, _gp /* Setup GP correctly if we're non-PIC. */ move $31, $0 +#endif +#ifdef L_rcrt1 +/* #if _MIPS_SIM == _MIPS_SIM_ABI32 */ + PTR_LA $4, _DYNAMIC /* Place _DYNAMIC into the GOT */ + REG_S $4, -0x7ff0($28) /* offset to GOT stolen from dl-startup */ + jal .L0 /* Get the current $pc address */ +.L0: + PTR_SUBU $4, $31, $25 /* Calculate load addr */ + move $31, $0 /* Clear ra */ + and $29, -2 * SZREG /* Ensure stack is aligned */ + PTR_ADDIU $29, (-2 * SZREG) /* Allocate 2 register spaces on stack */ + REG_S $2, SZREG($29) /* Store atexit in case it exists */ + PTR_LA $5, reloc_static_pie /* function calls before relocation + don't work unless we set $t9 manually */ + PTR_ADDU $25, $4, $5 /* store reloc_static_pie in $t9 */ + jalr $25 /* call reloc_static_pie */ + nop /* delay slot, just in case */ + REG_L $2, SZREG($29) /* cleanup stack */ + PTR_ADDIU $29, $29, (2 * SZREG) +#else + PTR_LA $4, _DYNAMIC /* Place _DYNAMIC into the GOT */ + REG_S $4, -0x7ff0($28) + +/* #endif */ + #endif PTR_LA $4, main /* main */ -- 2.34.1

1 0

aarch64 support still experimental?
by Lance Fredrickson 11 Aug '22

11 Aug '22

Just polling to see if anyone is using aarch64 in uclibc-ng. I created a toolchain from buildroot for some new hardware I got but noticed a lot of segfaulting with c++ applications. Thinking it was possibly a libstdc++ issue I opened a bug report. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106581 But it seems to concluded that uclibc-ng tls support for aarch64 isn't quite there. Some of the segfaulting is fixed if libstdc++ is static linked, but doesn't quite fix all the issues. https://lists.buildroot.org/pipermail/buildroot/2022-August/648961.html Also got this response on the buildroot mailing list. thank, Lanec

1 0

Odd thing in aarch64 support
by Thomas Petazzoni 11 Aug '22

11 Aug '22

Hello, While looking at some uClibc code, I stumbled across the following snippet in Rules.mak: UCLIBC_LDSO_NAME := ld-uClibc ARCH_NATIVE_BIT := 32 ifneq ($(findstring $(TARGET_ARCH) , hppa64 ia64 powerpc64 s390x sparc64 x86_64 kvx ),) UCLIBC_LDSO_NAME := ld64-uClibc ARCH_NATIVE_BIT := 64 else ifeq ($(CONFIG_MIPS_N64_ABI),y) UCLIBC_LDSO_NAME := ld64-uClibc ARCH_NATIVE_BIT := 64 endif endif I was surprised not to see aarch64 in the list of 64-bit architectures here. Turns out that the situation is not that simple in fact. Indeed, gcc does not expect all 64-bit architecture to have their dynamic loader called ld64-uClibc. For aarch64 specifically, it indeed assumes the dynamic loader is called ld-uClibc, which explains why it is working today. However, it means that ARCH_NATIVE_BIT is defined to 32 on aarch64, which is obviously (?) wrong. But turns out that ARCH_NATIVE_BIT is only used in utils/porting.h to define __WORDSIZE and __WORDSIZE is only used in utils/ldd.c. So to me, it seems like this would gain in being clarified. Something like (completely untested): diff --git a/Rules.mak b/Rules.mak index 3fb64c728..a0b012d7f 100644 --- a/Rules.mak +++ b/Rules.mak @@ -142,17 +142,8 @@ export MAJOR_VERSION MINOR_VERSION SUBLEVEL VERSION ABI_VERSION LC_ALL LIBC := libc SHARED_LIBNAME := $(LIBC).so.$(ABI_VERSION) -UCLIBC_LDSO_NAME := ld-uClibc -ARCH_NATIVE_BIT := 32 -ifneq ($(findstring $(TARGET_ARCH) , hppa64 ia64 powerpc64 s390x sparc64 x86_64 kvx ),) -UCLIBC_LDSO_NAME := ld64-uClibc -ARCH_NATIVE_BIT := 64 -else -ifeq ($(CONFIG_MIPS_N64_ABI),y) -UCLIBC_LDSO_NAME := ld64-uClibc -ARCH_NATIVE_BIT := 64 -endif -endif +UCLIBC_LDSO_NAME := $(call qstrip,$(TARGET_LDSO_NAME)) +ARCH_NATIVE_BIT := $(call qstrip,$(TARGET_ARCH_BITS)) UCLIBC_LDSO := $(UCLIBC_LDSO_NAME).so.$(ABI_VERSION) NONSHARED_LIBNAME := uclibc_nonshared.a diff --git a/extra/Configs/Config.in b/extra/Configs/Config.in index a49278b30..e6369bd82 100644 --- a/extra/Configs/Config.in +++ b/extra/Configs/Config.in @@ -145,6 +145,26 @@ config TARGET_xtensa endchoice +config TARGET_LDSO_NAME + string + default "ld64-uClibc" if TARGET_ia64 + default "ld64-uClibc" if TARGET_powerpc64 + default "ld64-uClibc" if TARGET_sparc64 + default "ld64-uClibc" if TARGET_x86_64 + default "ld64-uClibc" if TARGET_kvx + default "ld64-uClibc" if CONFIG_MIPS_N64_ABI + default "ld-uClibc" + +config TARGET_ARCH_BITS + int + default 64 if TARGET_aarch64 + default 64 if TARGET_ia64 + default 64 if TARGET_powerpc64 + default 64 if TARGET_sparc64 + default 64 if TARGET_x86_64 + default 64 if TARGET_kvx + default 64 if CONFIG_MIPS_N64_ABI + default 32 menu "Target Architecture Features and Options" Best regards, Thomas Petazzoni -- Thomas Petazzoni, co-owner and CEO, Bootlin Embedded Linux and Kernel engineering and training https://bootlin.com

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