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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

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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Missing RUSAGE_THREAD definition
by Thomas Petazzoni 11 Aug '22

11 Aug '22

Hello, uClibc-ng is missing the definition of RUSAGE_THREAD. It is available in glibc: sysdeps/unix/sysv/linux/alpha/bits/resource.h: RUSAGE_THREAD = 1 sysdeps/unix/sysv/linux/bits/resource.h: RUSAGE_THREAD = 1 sysdeps/unix/sysv/linux/mips/bits/resource.h: RUSAGE_THREAD = 1 sysdeps/unix/sysv/linux/sparc/bits/resource.h: RUSAGE_THREAD = 1 We have a real-world usage of RUSAGE_THREAD by the pistache project, https://github.com/oktal/pistache. Best regards, Thomas -- Thomas Petazzoni, co-owner and CEO, Bootlin Embedded Linux and Kernel engineering and training https://bootlin.com

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New release 1.0.42
by Waldemar Brodkorb 11 Aug '22

11 Aug '22

Hi, I released 1.0.42 today. See here the changelog: https://cgit.uclibc-ng.org/cgi/cgit/uclibc-ng.git/log/?h=v1.0.42 best regards Waldemar

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[PATCH] Added support for creation of Static Position-Independent Executable (PIE) on aarch64
by linted 28 Jul '22

28 Jul '22

Hello, Here is the next installment of static-pie support. This time it is for aarch64 (arm64). It uses the same relocation methods as i386, x86_64, and arm. The only other major difference is the disabling of stack protectors in reloc_static_pie.c since it can lead to access of dynamic memory prior to relocation. --- From b55075957b6a95e120095fb5d5dcc96bd500749e Mon Sep 17 00:00:00 2001 From: linted <linted(a)users.noreply.github.com> Date: Sat, 16 Jul 2022 16:23:45 -0400 Subject: [PATCH] Added support for creation of Static Position-Independent Executables (PIE) on aarch64 Updated config to allow compilation of rcrt1.o for aarch64 and modified it's crt1.S to relocate dynamic section prior to __uClibc_main. Disabled stack protector when compiling reloc_static_pie.c to avoid TLS access prior to it being setup. Signed-off-by: linted <linted(a)users.noreply.github.com> --- extra/Configs/Config.in | 2 +- libc/misc/internals/Makefile.in | 2 +- libc/sysdeps/linux/aarch64/crt1.S | 14 ++++++++++++++ 3 files changed, 16 insertions(+), 2 deletions(-) diff --git a/extra/Configs/Config.in b/extra/Configs/Config.in index a49278b30..7d7d374c3 100644 --- a/extra/Configs/Config.in +++ b/extra/Configs/Config.in @@ -304,7 +304,7 @@ 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) + depends on DOPIC && !UCLIBC_FORMAT_FDPIC_ELF && (TARGET_arm || TARGET_i386 || TARGET_x86_64 || TARGET_aarch64) config ARCH_HAS_NO_SHARED bool diff --git a/libc/misc/internals/Makefile.in b/libc/misc/internals/Makefile.in index 4a6e73d2d..69af8b76e 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) libc-y += $(MISC_INTERNALS_OBJ) ifneq ($(UCLIBC_FORMAT_SHARED_FLAT),y) diff --git a/libc/sysdeps/linux/aarch64/crt1.S b/libc/sysdeps/linux/aarch64/crt1.S index 09d0327ac..e9f946894 100644 --- a/libc/sysdeps/linux/aarch64/crt1.S +++ b/libc/sysdeps/linux/aarch64/crt1.S @@ -48,6 +48,20 @@ _start: mov x29, #0 mov x30, #0 +#ifdef L_rcrt1 + /* Save off the atexit pointer */ + mov x19, x0 + + /* Calculate load address... idk how this works, but it does */ + adrp x0, _start + + /* Do relocations */ + bl reloc_static_pie + + /* restore atexit pointer */ + mov x0, x19 +#endif + /* Setup _fini in argument register */ mov x5, x0 -- 2.34.1

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[PATCH 1/2] linuxthreads/arm: fix ldrex/strex loop when built with O0
by Vladimir Murzin 26 Jul '22

26 Jul '22

O0 build result in the following codegen 00000000 <ldrex>: 0: b480 push {r7} 2: b085 sub sp, #20 4: af00 add r7, sp, #0 6: 6078 str r0, [r7, #4] 8: 687b ldr r3, [r7, #4] a: e853 3f00 ldrex r3, [r3] e: 60fb str r3, [r7, #12] 10: 68fb ldr r3, [r7, #12] 12: 4618 mov r0, r3 14: 3714 adds r7, #20 16: 46bd mov sp, r7 18: f85d 7b04 ldr.w r7, [sp], #4 1c: 4770 bx lr 0000001e <strex>: 1e: b480 push {r7} 20: b085 sub sp, #20 22: af00 add r7, sp, #0 24: 6078 str r0, [r7, #4] 26: 6039 str r1, [r7, #0] 28: 687b ldr r3, [r7, #4] 2a: 683a ldr r2, [r7, #0] 2c: e842 3300 strex r3, r3, [r2] 30: 60fb str r3, [r7, #12] 32: 68fb ldr r3, [r7, #12] 34: 4618 mov r0, r3 36: 3714 adds r7, #20 38: 46bd mov sp, r7 3a: f85d 7b04 ldr.w r7, [sp], #4 3e: 4770 bx lr 00000040 <testandset>: 40: b590 push {r4, r7, lr} 42: b083 sub sp, #12 44: af00 add r7, sp, #0 46: 6078 str r0, [r7, #4] 48: 6878 ldr r0, [r7, #4] 4a: f7ff fffe bl 0 <ldrex> 4e: 4603 mov r3, r0 50: 461c mov r4, r3 52: 6879 ldr r1, [r7, #4] 54: 2001 movs r0, #1 56: f7ff fffe bl 1e <strex> 5a: 4603 mov r3, r0 5c: 2b00 cmp r3, #0 5e: d1f3 bne.n 48 <testandset+0x8> 60: 4623 mov r3, r4 62: 4618 mov r0, r3 64: 370c adds r7, #12 66: 46bd mov sp, r7 68: bd90 pop {r4, r7, pc} ARM ARM suggests that LoadExcl/StoreExcl loops are guaranteed to make forward progress only if, for any LoadExcl/StoreExcl loop within a single thread of execution, the software meets all of the following conditions: 1 Between the Load-Exclusive and the Store-Exclusive, there are no explicit memory accesses, preloads, direct or indirect System register writes, address translation instructions, cache or TLB maintenance instructions, exception generating instructions, exception returns, or indirect branches. ... Obviously condition is not met for O0 builds. O2 build (which is highly likely the most common setting) able to do the right thing resulting in 00000000 <ldrex>: 0: e850 0f00 ldrex r0, [r0] 4: 4770 bx lr 6: bf00 nop 00000008 <strex>: 8: e841 0000 strex r0, r0, [r1] c: 4770 bx lr e: bf00 nop 00000010 <testandset>: 10: 2101 movs r1, #1 12: 4603 mov r3, r0 14: e853 0f00 ldrex r0, [r3] 18: e843 1200 strex r2, r1, [r3] 1c: 2a00 cmp r2, #0 1e: d1f9 bne.n 14 <testandset+0x4> 20: 4770 bx lr 22: bf00 nop Rather than depending on level of optimisation implement whole ldrex/strex loop in inline assembly. Signed-off-by: Vladimir Murzin <vladimir.murzin(a)arm.com> --- .../linuxthreads/sysdeps/arm/pt-machine.h | 34 +++++-------------- 1 file changed, 9 insertions(+), 25 deletions(-) diff --git a/libpthread/linuxthreads/sysdeps/arm/pt-machine.h b/libpthread/linuxthreads/sysdeps/arm/pt-machine.h index fc17e9bc7..b00b10495 100644 --- a/libpthread/linuxthreads/sysdeps/arm/pt-machine.h +++ b/libpthread/linuxthreads/sysdeps/arm/pt-machine.h @@ -29,35 +29,19 @@ #endif #if defined(__thumb2__) -PT_EI long int ldrex(int *spinlock) -{ - long int ret; - __asm__ __volatile__( - "ldrex %0, [%1]\n" - : "=r"(ret) - : "r"(spinlock) : "memory"); - return ret; -} - -PT_EI long int strex(int val, int *spinlock) -{ - long int ret; - __asm__ __volatile__( - "strex %0, %1, [%2]\n" - : "=r"(ret) - : "r" (val), "r"(spinlock) : "memory"); - return ret; -} - /* Spinlock implementation; required. */ PT_EI long int testandset (int *spinlock) { - register unsigned int ret; - - do { - ret = ldrex(spinlock); - } while (strex(1, spinlock)); + unsigned int ret, tmp, val = 1; + + __asm__ __volatile__ ( +"0: ldrex %0, [%2] \n" +" strex %1, %3, [%2] \n" +" cmp %1, #0 \n" +" bne 0b" + : "=&r" (ret), "=&r" (tmp) + : "r" (spinlock), "r" (val) : "memory", "cc"); return ret; } -- 2.25.1

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