devel September 2022

devel@uclibc-ng.org

7 participants
12 discussions

[Patch] static pie porting docs
by linted 27 Sep '22

27 Sep '22

Hello again! Since we have the steps pretty well fleshed out, I figured it was about time to update the porting docs to describe how to add support for static-pie. Here is a patch with some notes about the steps I usually take when updating another architecture to support it. -- From afaa287e28e8e120bf55a7de368253f445a6deea Mon Sep 17 00:00:00 2001 From: linted <linted(a)users.noreply.github.com> Date: Mon, 26 Sep 2022 13:40:50 -0400 Subject: [PATCH] Added some documentation on how to add static-pie support to the porting guide Signed-off-by: linted <linted(a)users.noreply.github.com> --- docs/porting.txt | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/docs/porting.txt b/docs/porting.txt index 380645801..31c188ae1 100644 --- a/docs/porting.txt +++ b/docs/porting.txt @@ -12,6 +12,8 @@ you are hacking on. the shared library loader work requires you first have basic architecture support working. Thus you should add ARCH_HAS_NO_SHARED and ARCH_HAS_NO_LDSO to Config.ARCH's TARGET_ARCH +- When static pie support is added this TARGET_arch can be appended to the + list in extra/Configs/Config.in ==================== === libc sysdeps === @@ -56,6 +58,15 @@ you are hacking on. usually these are written in assembler, but you may be able to cheat and write them in C ... see other ports for more information +- Once static and pie executables are stable, static-pie support can be + added by modifying crt1.S to calculate the address that the kernel loaded + the main elf. Once the elf load address is found, call reloc_static_pie to + perform all the dynamic relocations normally handled by ldso. This new + code should be placed at the begining of _start and surrounded by defines + so that it is only compiled into rcrt1.o and not the static or shared + versions. This is usually done by using the special L_rcrt1 preprocessor + define. i386 and x86_64 have good reference implementations. + ==================== === ldso sysdeps === ==================== -- 2.34.1

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[PATCH 0/2] tests: adaptation for ARCv3
by Pavel.Kozlov＠synopsys.com 27 Sep '22

27 Sep '22

From: Pavel Kozlov <pavel.kozlov(a)synopsys.com> Hello, The first patch allows to use general ARC TLS macro for ARCv3 and allows to build tests for ARCv3. The second patch contains fix for the TLS_GD macro. This patch series is associated with uclibc-ng ARCv3 patches: Link: https://mailman.openadk.org/mailman3/hyperkitty/list/devel@uclibc-ng.org/th… Pavel Kozlov (1): arc: fix TLS_GD macro, bad clobber list Sergey Matyukevich (1): arc: use existing tls macros for ARCv3 32-bit CPUs test/tls/tls-macros-arc.h | 14 ++++++-------- test/tls/tls-macros.h | 2 +- 2 files changed, 7 insertions(+), 9 deletions(-) base-commit: 728e1e0ea5adf1bd9b479e4edc456b637e26c031 -- 2.25.1

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[PATCH 0/4] add support for ARCv3 32-bit processors
by Pavel.Kozlov＠synopsys.com 27 Sep '22

27 Sep '22

From: Pavel Kozlov <pavel.kozlov(a)synopsys.com> Hello, this patch series adds base support for ARCv3 32-bit architecture, adds new machine identifer and handle changes in ISA and ARC toolchain. New ARCv3 ISA includes both 64-bit and 32-bit CPU family. This patch series adds support for 32-bit ARCv3 HS5x processors. Sergey Matyukevich (4): arc: minor cleanup for ARCv2 ldso: arc: add compiler option check arc: add asm macros arc: add support for ARCv3 32-bit processors include/elf.h | 3 +- ldso/ldso/Makefile.in | 3 +- ldso/ldso/arc/dl-sysdep.h | 3 ++ ldso/ldso/arc/resolve.S | 45 +++++++++++----------- libc/sysdeps/linux/arc/asm.h | 52 ++++++++++++++++++++++++++ libc/sysdeps/linux/arc/bits/syscalls.h | 4 +- libc/sysdeps/linux/arc/crt1.S | 4 +- utils/ldd.c | 7 +++- 8 files changed, 93 insertions(+), 28 deletions(-) create mode 100644 libc/sysdeps/linux/arc/asm.h base-commit: d46709504efa46e5b9b52739a48ab61b39fd4971 -- 2.25.1

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[PATCH v2 0/5] add static PIE support for xtensa
by Max Filippov 21 Sep '22

21 Sep '22

Hello, this series does a couple cleanups in the ldso, static PIE code and xtensa code and enables static PIE support for the xtensa architecture. Changes v1->v2: - clean up PERFORM_BOOTSTRAP_GOT condition in the ldso - drop patch that adds PERFORM_BOOTSTRAP_GOT to reloc_static_pie Max Filippov (5): static pie: fix building static PDE ldso: clean up PERFORM_BOOTSTRAP_GOT ifdeferry xtensa: ldso: make GOT protection adjustment conditional xtensa: drop ARCH_NEEDS_BOOTSTRAP_RELOCS xtensa: add static pie support extra/Configs/Config.in | 4 +++- ldso/ldso/dl-startup.c | 3 --- ldso/ldso/xtensa/dl-startup.h | 15 ++++-------- ldso/ldso/xtensa/dl-sysdep.h | 3 --- libc/misc/internals/reloc_static_pie.c | 6 ++--- libc/sysdeps/linux/xtensa/crt1.S | 27 ++++++++++++++++++++++ libpthread/nptl/sysdeps/generic/libc-tls.c | 7 ++++-- 7 files changed, 42 insertions(+), 23 deletions(-) -- 2.30.2

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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

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[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

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[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

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[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

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[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

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[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

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