devel August 2022

devel@uclibc-ng.org

4 participants
5 discussions

by linted

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 years, 3 months

aarch64 support still experimental?

by Lance Fredrickson

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

2 years, 4 months

Odd thing in aarch64 support

by Thomas Petazzoni

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

2 years, 4 months

Missing RUSAGE_THREAD definition

by Thomas Petazzoni

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

2 years, 4 months

New release 1.0.42

by Waldemar Brodkorb

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

2 years, 4 months

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devel August 2022