[uclibc-ng-devel,v4] Static PIE support for i386, x86_64, and arm

Hello,

I first want to apologize for so many patch versions.

This version of the patch correctly adjusts the offset of the TLS initimage
used by __libc_setup_tls when copying.

I would love feedback on my modifications to libc-tls.c as I had to use a
new global variable defined in reloc_static_pie.c containing the load
address. Originally I attempted to copy how glibc pulls the load address
from a memory map when initializing the TLS, however I could not find a
similar structure available in __libc_setup_tls. I would love to know if
there is a better method which I overlooked.



From 30b435a0b7a7f2d4323eafea2bcebb087cc62462 Mon Sep 17 00:00:00 2001
From: linted <linted@users.noreply.github.com>
Date: Sat, 23 Jul 2022 16:25:41 -0400
Subject: [PATCH] Added support for creation of Static Position-Independent
 Executables (PIE) on i386, x86_64, and arm.

This patch adds the generation of rcrt1.o which is used by gcc when
compiling with the --static-pie flag.

rcrt1.o differs from crt1.o and Scrt1.o in that it the executable has a
dynamic section but no relocations have been performed prior to _start
being called.
crt1.o assumes there to be no dynamic relocations, and Scrt1.o has all
relocations performed prior to execution by lsdo.

The new reloc_static_pie function handles parsing the dynamic section, and
performing the relocations in a architecture agnostic method.
It also sets _dl_load_base which is used when initalizing TLS to ensure
loading from the proper location.
This allows for easier porting of static-pie support to additional
architectures as only modifications to crt1.S to find the load address are
required.

Signed-off-by: linted <linted@users.noreply.github.com>
---
 Makerules                                   |  5 +++
 extra/Configs/Config.in                     |  5 +++
 libc/misc/internals/Makefile.in             |  1 +
 libc/misc/internals/reloc_static_pie.c      | 47 +++++++++++++++++++++
 libc/sysdeps/linux/arm/crt1.S               | 19 +++++++++
 libc/sysdeps/linux/i386/crt1.S              | 20 +++++++++
 libc/sysdeps/linux/x86_64/crt1.S            | 16 ++++++-
 libpthread/nptl/sysdeps/generic/Makefile.in |  4 ++
 libpthread/nptl/sysdeps/generic/libc-tls.c  |  4 ++
 9 files changed, 120 insertions(+), 1 deletion(-)
 create mode 100644 libc/misc/internals/reloc_static_pie.c

I've compiled a bunch of stuff for arm with this new patch and it seems 
to be running well everything I've thrown at it. Nice! Personally I 
wouldn't care if it took a dozen revisions. I'm just ecstatic to see 
uclibc still getting development.

I've submitted the -static-pie patch for arm for gcc here.
https://gcc.gnu.org/pipermail/gcc-patches/2022-July/598610.html

Some of these large projects like gcc and llvm, I've sent bug reports 
and some patches, but there's just so much volume of stuff it's hard to 
get anyone's attention it seems. I'll wait a couple weeks before pinging 
it again, but if anyone else wants to chime in on the gcc mailing list 
that the patch is working for them would be cool :)

Lance

On 7/23/2022 2:44 PM, linted wrote:
> Hello,
>
> I first want to apologize for so many patch versions.
>
> This version of the patch correctly adjusts the offset of the TLS 
> initimage used by __libc_setup_tls when copying.
>
> I would love feedback on my modifications to libc-tls.c as I had to 
> use a new global variable defined in reloc_static_pie.c containing the 
> load address. Originally I attempted to copy how glibc pulls the load 
> address from a memory map when initializing the TLS, however I could 
> not find a similar structure available in __libc_setup_tls. I would 
> love to know if there is a better method which I overlooked.

Hi,

applied and pushed,

best regards
 Waldemar

linted wrote,

> Hello,
> 
> I first want to apologize for so many patch versions.
> 
> This version of the patch correctly adjusts the offset of the TLS initimage
> used by __libc_setup_tls when copying.
> 
> I would love feedback on my modifications to libc-tls.c as I had to use a new
> global variable defined in reloc_static_pie.c containing the load address.
> Originally I attempted to copy how glibc pulls the load address from a memory
> map when initializing the TLS, however I could not find a similar structure
> available in __libc_setup_tls. I would love to know if there is a better method
> which I overlooked.
> 
> 
> 
> From 30b435a0b7a7f2d4323eafea2bcebb087cc62462 Mon Sep 17 00:00:00 2001
> From: linted <linted@users.noreply.github.com>
> Date: Sat, 23 Jul 2022 16:25:41 -0400
> Subject: [PATCH] Added support for creation of Static Position-Independent
>  Executables (PIE) on i386, x86_64, and arm.
> 
> This patch adds the generation of rcrt1.o which is used by gcc when compiling
> with the --static-pie flag.
> 
> rcrt1.o differs from crt1.o and Scrt1.o in that it the executable has a dynamic
> section but no relocations have been performed prior to _start being called.
> crt1.o assumes there to be no dynamic relocations, and Scrt1.o has all
> relocations performed prior to execution by lsdo.
> 
> The new reloc_static_pie function handles parsing the dynamic section, and
> performing the relocations in a architecture agnostic method.
> It also sets _dl_load_base which is used when initalizing TLS to ensure loading
> from the proper location.
> This allows for easier porting of static-pie support to additional
> architectures as only modifications to crt1.S to find the load address are
> required.
> 
> Signed-off-by: linted <linted@users.noreply.github.com>
> ---
>  Makerules                                   |  5 +++
>  extra/Configs/Config.in                     |  5 +++
>  libc/misc/internals/Makefile.in             |  1 +
>  libc/misc/internals/reloc_static_pie.c      | 47 +++++++++++++++++++++
>  libc/sysdeps/linux/arm/crt1.S               | 19 +++++++++
>  libc/sysdeps/linux/i386/crt1.S              | 20 +++++++++
>  libc/sysdeps/linux/x86_64/crt1.S            | 16 ++++++-
>  libpthread/nptl/sysdeps/generic/Makefile.in |  4 ++
>  libpthread/nptl/sysdeps/generic/libc-tls.c  |  4 ++
>  9 files changed, 120 insertions(+), 1 deletion(-)
>  create mode 100644 libc/misc/internals/reloc_static_pie.c
> 
> diff --git a/Makerules b/Makerules
> index fd40e6c7b..845d81897 100644
> --- a/Makerules
> +++ b/Makerules
> @@ -405,8 +405,13 @@ else
>  CRTS=$(top_builddir)lib/$(CRT).o
>  endif
>  
> +ifeq ($(STATIC_PIE),y)
> +CRTS+=$(top_builddir)lib/r$(CRT).o
> +endif
> +
>  ASFLAGS-$(CRT).o := -DL_$(CRT)
>  ASFLAGS-S$(CRT).o := $(PIEFLAG) -DL_S$(CRT)
> +ASFLAGS-r$(CRT).o := $(PIEFLAG) -DL_r$(CRT)
>  $(CRTS): $(top_srcdir)libc/sysdeps/linux/$(TARGET_ARCH)/$(CRT).S
>   $(compile.S)
>   $(Q)$(STRIPTOOL) -x -R .note -R .comment $@
> diff --git a/extra/Configs/Config.in b/extra/Configs/Config.in
> index a58ceb265..a49278b30 100644
> --- a/extra/Configs/Config.in
> +++ b/extra/Configs/Config.in
> @@ -301,6 +301,11 @@ config DOPIC
>    If you wish to build all of uClibc as PIC objects, then answer Y here.
>    If you are unsure, then you should answer N.
>  
> +config STATIC_PIE
> + bool "Add support for Static Position Independent Executables (PIE)"
> + default n
> + depends on DOPIC && !UCLIBC_FORMAT_FDPIC_ELF && (TARGET_arm || TARGET_i386 ||
> TARGET_x86_64)
> +
>  config ARCH_HAS_NO_SHARED
>   bool
>  
> diff --git a/libc/misc/internals/Makefile.in b/libc/misc/internals/Makefile.in
> index a8e4e36f9..4a6e73d2d 100644
> --- a/libc/misc/internals/Makefile.in
> +++ b/libc/misc/internals/Makefile.in
> @@ -34,6 +34,7 @@ libc-static-$(UCLIBC_FORMAT_FLAT_SEP_DATA) += \
>  libc-static-$(UCLIBC_FORMAT_SHARED_FLAT) += \
>    $(MISC_INTERNALS_OUT)/shared_flat_initfini.o \
>    $(MISC_INTERNALS_OUT)/shared_flat_add_library.o
> +libc-static-$(STATIC_PIE) += $(MISC_INTERNALS_OUT)/reloc_static_pie.o
>  libc-shared-$(UCLIBC_FORMAT_SHARED_FLAT) += \
>    $(MISC_INTERNALS_OUT)/shared_flat_initfini.os \
>    $(MISC_INTERNALS_OUT)/shared_flat_add_library.os
> diff --git a/libc/misc/internals/reloc_static_pie.c b/libc/misc/internals/
> reloc_static_pie.c
> new file mode 100644
> index 000000000..578202d23
> --- /dev/null
> +++ b/libc/misc/internals/reloc_static_pie.c
> @@ -0,0 +1,47 @@
> +/* Support for relocating static PIE.
> +   Copyright (C) 2017-2022 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   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/>.  */
> +
> +#include <link.h>
> +#include <elf.h>
> +#include <dl-elf.h>
> +
> +ElfW(Addr) _dl_load_base = NULL;
> +
> +void
> +reloc_static_pie (ElfW(Addr) load_addr);
> +
> +void
> +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};
> +
> +    /* Read our own dynamic section and fill in the info array.  */
> +    dyn_addr = ((void *) load_addr + elf_machine_dynamic ());
> +
> +    /* Use the underlying function to avoid TLS access before initialization *
> /
> +    __dl_parse_dynamic_info(dyn_addr, dynamic_info, NULL, load_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);
> +    _dl_load_base = load_addr;
> +}
> diff --git a/libc/sysdeps/linux/arm/crt1.S b/libc/sysdeps/linux/arm/crt1.S
> index a1d7f0f23..fade1d25c 100644
> --- a/libc/sysdeps/linux/arm/crt1.S
> +++ b/libc/sysdeps/linux/arm/crt1.S
> @@ -246,6 +246,22 @@ _start:
>   mov lr, #0
>  
>  #ifdef __ARCH_USE_MMU__
> +#ifdef L_rcrt1
> + /* We don't need to save a1 since no dynamic linker should have run */
> + ldr a1, .L_GOT          /* Get value at .L_GOT + 0  (offset to GOT)*/
> + adr a2, .L_GOT          /* Get address of .L_GOT */
> + ldr a3, .L_GOT+16       /* Get value of _start(GOT) stored in .L_GOT */
> + adr a4, _start          /* Get address of _start after relocation (changes to
> pc - ~30 or so) */
> + add a1, a1, a2          /* Calculate where the GOT is */
> + ldr a2, [a1, a3]        /* GOT + _start(GOT) = offset of _start from begin of
> file */
> + sub a1, a4, a2          /* Current addr of _start - offset from beginning of
> file = load addr */
> + bl reloc_static_pie
> + mov a1, #0              /* Clean up a1 so that a random address won't get
> called at the end of program */
> +
> + /* Clear the frame pointer and link register again since it might be modified
> by previous call */
> + mov fp, #0
> + mov lr, #0
> +#endif
>   /* Pop argc off the stack and save a pointer to argv */
>   ldr a2, [sp], #4
>   mov a3, sp
> @@ -309,6 +325,9 @@ _start:
>   .word _fini(GOT)
>   .word _init(GOT)
>   .word main(GOT)
> +#ifdef L_rcrt1
> + .word _start(GOT)
> +#endif
>  #endif
>  #endif
>  
> diff --git a/libc/sysdeps/linux/i386/crt1.S b/libc/sysdeps/linux/i386/crt1.S
> index 35a6552e8..decc68967 100644
> --- a/libc/sysdeps/linux/i386/crt1.S
> +++ b/libc/sysdeps/linux/i386/crt1.S
> @@ -67,6 +67,9 @@
>  #endif
>  .type   main,%function
>  .type   __uClibc_main,%function
> +#ifdef L_rcrt1
> +.type reloc_static_pie,%function
> +#endif
>  _start:
>   /* Clear the frame pointer.  The ABI suggests this be done, to mark
>     the outermost frame obviously.  */
> @@ -100,6 +103,23 @@ _start:
>   pop %ebx
>   addl $_GLOBAL_OFFSET_TABLE_+[.-.L0],%ebx
>  
> +#ifdef L_rcrt1
> + /* We cannot rely on _DYNAMIC being usable here due to RELRO.
> +   Instead we calculate the load address based off a symbol
> +   that we know will exist, _start. */
> + pushl %ecx                      /* Save ecx so it won't get clobbered */
> + pushl %ebx                      /* Save ebx so it won't get clobbered */
> + xorl %ecx, %ecx                 /* Clear ecx */
> + addl _start@GOT(%ebx), %ecx     /* Get the offset of _start */
> + movl _start@GOT(%ebx), %eax     /* Get the run time address of _start */
> + subl %ecx, %eax                 /* Subtract to find the load address */
> + pushl %eax                      /* Pass the load address */
> + call reloc_static_pie@PLT
> + popl %eax                       /* Clean up from function call */
> + popl %ebx                       /* Restore the GOT address */
> + popl %ecx                       /* restore ecx */
> +#endif
> +
>   /* Push address of our own entry points to .fini and .init.  */
>   pushl _fini@GOT(%ebx)
>   pushl _init@GOT(%ebx)
> diff --git a/libc/sysdeps/linux/x86_64/crt1.S b/libc/sysdeps/linux/x86_64/
> crt1.S
> index 87777dd5d..701cbf2f6 100644
> --- a/libc/sysdeps/linux/x86_64/crt1.S
> +++ b/libc/sysdeps/linux/x86_64/crt1.S
> @@ -80,6 +80,20 @@ _start:
>     the outermost frame obviously.  */
>   xorl %ebp, %ebp
>  
> +#ifdef L_rcrt1
> + pushq %rdi                          /* save rdi (but should be 0...) */
> + pushq %rdx                          /* store rdx (rtld_fini) */
> + xorq %rcx, %rcx                     /* ensure rcx is 0 */
> + addq _start@GOTPCREL(%rip), %rcx    /* get offset of _start from beginning of
> file */
> + movq _start@GOTPCREL(%rip), %rax    /* get run time address of _start */
> + subq %rcx, %rax                     /* calculate run time load offset */
> + movq %rax, %rdi                     /* load offset -> param 1 */
> + call reloc_static_pie               /* relocate dynamic addrs */
> + xorq %rax, %rax                     /* cleanup */
> + popq %rdx
> + popq %rdi
> +#endif
> +
>   /* Extract the arguments as encoded on the stack and set up
>     the arguments for __libc_start_main (int (*main) (int, char **, char **),
>     int argc, char *argv,
> @@ -107,7 +121,7 @@ _start:
>     which grow downwards).  */
>   pushq %rsp
>  
> -#if defined(L_Scrt1)
> +#if defined(L_Scrt1) || defined(L_rcrt1)
>   /* Give address for main() */
>   movq main@GOTPCREL(%rip), %rdi
>  
> diff --git a/libpthread/nptl/sysdeps/generic/Makefile.in b/libpthread/nptl/
> sysdeps/generic/Makefile.in
> index eb656ee17..a5ba9bbe8 100644
> --- a/libpthread/nptl/sysdeps/generic/Makefile.in
> +++ b/libpthread/nptl/sysdeps/generic/Makefile.in
> @@ -13,6 +13,10 @@ subdirs += libpthread/nptl/sysdeps/generic
>  libpthread_generic_DIR := $(top_srcdir)libpthread/nptl/sysdeps/generic
>  libpthread_generic_OUT := $(top_builddir)libpthread/nptl/sysdeps/generic
>  
> +ifeq ($(STATIC_PIE),y)
> +CFLAGS-libc-tls.c := -DSTATIC_PIE
> +endif
> +
>  libpthread_generic_libc_a_CSRC = libc-tls.c
>  libpthread_generic_libc_a_COBJ = $(patsubst %.c,$(libpthread_generic_OUT)/
> %.o,$(libpthread_generic_libc_a_CSRC))
>  libpthread_generic_libc_a_OBJS = $(libpthread_generic_libc_a_COBJ)
> diff --git a/libpthread/nptl/sysdeps/generic/libc-tls.c b/libpthread/nptl/
> sysdeps/generic/libc-tls.c
> index d746c9a38..0c8c558d0 100644
> --- a/libpthread/nptl/sysdeps/generic/libc-tls.c
> +++ b/libpthread/nptl/sysdeps/generic/libc-tls.c
> @@ -142,6 +142,10 @@ __libc_setup_tls (size_t tcbsize, size_t tcbalign)
>    initimage = (void *) &__tdata_start;
>  #else
>    initimage = (void *) phdr->p_vaddr;
> +#if !defined(SHARED) && defined(STATIC_PIE)
> +    extern ElfW(Addr) _dl_load_base;
> +    initimage += _dl_load_base;
> +#endif
>  #endif
>    align = phdr->p_align;
>    if (phdr->p_align > max_align)
> --
> 2.34.1
> 
> 

> From 30b435a0b7a7f2d4323eafea2bcebb087cc62462 Mon Sep 17 00:00:00 2001
> From: linted <linted@users.noreply.github.com>
> Date: Sat, 23 Jul 2022 16:25:41 -0400
> Subject: [PATCH] Added support for creation of Static Position-Independent
>  Executables (PIE) on i386, x86_64, and arm.
> 
> This patch adds the generation of rcrt1.o which is used by gcc when compiling with the --static-pie flag.
> 
> rcrt1.o differs from crt1.o and Scrt1.o in that it the executable has a dynamic section but no relocations have been performed prior to _start being called.
> crt1.o assumes there to be no dynamic relocations, and Scrt1.o has all relocations performed prior to execution by lsdo.
> 
> The new reloc_static_pie function handles parsing the dynamic section, and performing the relocations in a architecture agnostic method.
> It also sets _dl_load_base which is used when initalizing TLS to ensure loading from the proper location.
> This allows for easier porting of static-pie support to additional architectures as only modifications to crt1.S to find the load address are required.
> 
> Signed-off-by: linted <linted@users.noreply.github.com>
> ---
>  Makerules                                   |  5 +++
>  extra/Configs/Config.in                     |  5 +++
>  libc/misc/internals/Makefile.in             |  1 +
>  libc/misc/internals/reloc_static_pie.c      | 47 +++++++++++++++++++++
>  libc/sysdeps/linux/arm/crt1.S               | 19 +++++++++
>  libc/sysdeps/linux/i386/crt1.S              | 20 +++++++++
>  libc/sysdeps/linux/x86_64/crt1.S            | 16 ++++++-
>  libpthread/nptl/sysdeps/generic/Makefile.in |  4 ++
>  libpthread/nptl/sysdeps/generic/libc-tls.c  |  4 ++
>  9 files changed, 120 insertions(+), 1 deletion(-)
>  create mode 100644 libc/misc/internals/reloc_static_pie.c
> 
> diff --git a/Makerules b/Makerules
> index fd40e6c7b..845d81897 100644
> --- a/Makerules
> +++ b/Makerules
> @@ -405,8 +405,13 @@ else
>  CRTS=$(top_builddir)lib/$(CRT).o
>  endif
>  
> +ifeq ($(STATIC_PIE),y)
> +CRTS+=$(top_builddir)lib/r$(CRT).o
> +endif
> +
>  ASFLAGS-$(CRT).o := -DL_$(CRT)
>  ASFLAGS-S$(CRT).o := $(PIEFLAG) -DL_S$(CRT)
> +ASFLAGS-r$(CRT).o := $(PIEFLAG) -DL_r$(CRT)
>  $(CRTS): $(top_srcdir)libc/sysdeps/linux/$(TARGET_ARCH)/$(CRT).S
>  	$(compile.S)
>  	$(Q)$(STRIPTOOL) -x -R .note -R .comment $@
> diff --git a/extra/Configs/Config.in b/extra/Configs/Config.in
> index a58ceb265..a49278b30 100644
> --- a/extra/Configs/Config.in
> +++ b/extra/Configs/Config.in
> @@ -301,6 +301,11 @@ config DOPIC
>  	  If you wish to build all of uClibc as PIC objects, then answer Y here.
>  	  If you are unsure, then you should answer N.
>  
> +config STATIC_PIE
> +	bool "Add support for Static Position Independent Executables (PIE)"
> +	default n
> +	depends on DOPIC && !UCLIBC_FORMAT_FDPIC_ELF && (TARGET_arm || TARGET_i386 || TARGET_x86_64)
> +
>  config ARCH_HAS_NO_SHARED
>  	bool
>  
> diff --git a/libc/misc/internals/Makefile.in b/libc/misc/internals/Makefile.in
> index a8e4e36f9..4a6e73d2d 100644
> --- a/libc/misc/internals/Makefile.in
> +++ b/libc/misc/internals/Makefile.in
> @@ -34,6 +34,7 @@ libc-static-$(UCLIBC_FORMAT_FLAT_SEP_DATA) += \
>  libc-static-$(UCLIBC_FORMAT_SHARED_FLAT) += \
>    $(MISC_INTERNALS_OUT)/shared_flat_initfini.o \
>    $(MISC_INTERNALS_OUT)/shared_flat_add_library.o
> +libc-static-$(STATIC_PIE) += $(MISC_INTERNALS_OUT)/reloc_static_pie.o
>  libc-shared-$(UCLIBC_FORMAT_SHARED_FLAT) += \
>    $(MISC_INTERNALS_OUT)/shared_flat_initfini.os \
>    $(MISC_INTERNALS_OUT)/shared_flat_add_library.os
> diff --git a/libc/misc/internals/reloc_static_pie.c b/libc/misc/internals/reloc_static_pie.c
> new file mode 100644
> index 000000000..578202d23
> --- /dev/null
> +++ b/libc/misc/internals/reloc_static_pie.c
> @@ -0,0 +1,47 @@
> +/* Support for relocating static PIE.
> +   Copyright (C) 2017-2022 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   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/>.  */
> +
> +#include <link.h>
> +#include <elf.h>
> +#include <dl-elf.h>
> +
> +ElfW(Addr) _dl_load_base = NULL;
> +
> +void
> +reloc_static_pie (ElfW(Addr) load_addr);
> +
> +void
> +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};
> +
> +    /* Read our own dynamic section and fill in the info array.  */
> +    dyn_addr = ((void *) load_addr + elf_machine_dynamic ());
> +
> +    /* Use the underlying function to avoid TLS access before initialization */
> +    __dl_parse_dynamic_info(dyn_addr, dynamic_info, NULL, load_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);
> +    _dl_load_base = load_addr;
> +}
> diff --git a/libc/sysdeps/linux/arm/crt1.S b/libc/sysdeps/linux/arm/crt1.S
> index a1d7f0f23..fade1d25c 100644
> --- a/libc/sysdeps/linux/arm/crt1.S
> +++ b/libc/sysdeps/linux/arm/crt1.S
> @@ -246,6 +246,22 @@ _start:
>  	mov lr, #0
>  
>  #ifdef __ARCH_USE_MMU__
> +#ifdef L_rcrt1
> +	/* We don't need to save a1 since no dynamic linker should have run */
> +	ldr a1, .L_GOT          /* Get value at .L_GOT + 0  (offset to GOT)*/
> +	adr a2, .L_GOT          /* Get address of .L_GOT */
> +	ldr a3, .L_GOT+16       /* Get value of _start(GOT) stored in .L_GOT */
> +	adr a4, _start          /* Get address of _start after relocation (changes to pc - ~30 or so) */
> +	add a1, a1, a2          /* Calculate where the GOT is */
> +	ldr a2, [a1, a3]        /* GOT + _start(GOT) = offset of _start from begin of file */
> +	sub a1, a4, a2          /* Current addr of _start - offset from beginning of file = load addr */
> +	bl reloc_static_pie
> +	mov a1, #0              /* Clean up a1 so that a random address won't get called at the end of program */
> +
> +	/* Clear the frame pointer and link register again since it might be modified by previous call */
> +	mov fp, #0
> +	mov lr, #0
> +#endif
>  	/* Pop argc off the stack and save a pointer to argv */
>  	ldr a2, [sp], #4
>  	mov a3, sp
> @@ -309,6 +325,9 @@ _start:
>  	.word _fini(GOT)
>  	.word _init(GOT)
>  	.word main(GOT)
> +#ifdef L_rcrt1
> +	.word _start(GOT)
> +#endif
>  #endif
>  #endif
>  
> diff --git a/libc/sysdeps/linux/i386/crt1.S b/libc/sysdeps/linux/i386/crt1.S
> index 35a6552e8..decc68967 100644
> --- a/libc/sysdeps/linux/i386/crt1.S
> +++ b/libc/sysdeps/linux/i386/crt1.S
> @@ -67,6 +67,9 @@
>  #endif
>  .type   main,%function
>  .type   __uClibc_main,%function
> +#ifdef L_rcrt1
> +.type	reloc_static_pie,%function
> +#endif
>  _start:
>  	/* Clear the frame pointer.  The ABI suggests this be done, to mark
>  	   the outermost frame obviously.  */
> @@ -100,6 +103,23 @@ _start:
>  	pop %ebx
>  	addl $_GLOBAL_OFFSET_TABLE_+[.-.L0],%ebx
>  
> +#ifdef L_rcrt1
> +	/* We cannot rely on _DYNAMIC being usable here due to RELRO.
> +	   Instead we calculate the load address based off a symbol
> +	   that we know will exist, _start. */
> +	pushl %ecx                      /* Save ecx so it won't get clobbered */
> +	pushl %ebx                      /* Save ebx so it won't get clobbered */
> +	xorl %ecx, %ecx                 /* Clear ecx */
> +	addl _start@GOT(%ebx), %ecx     /* Get the offset of _start */
> +	movl _start@GOT(%ebx), %eax     /* Get the run time address of _start */
> +	subl %ecx, %eax                 /* Subtract to find the load address */
> +	pushl %eax                      /* Pass the load address */
> +	call reloc_static_pie@PLT
> +	popl %eax                       /* Clean up from function call */
> +	popl %ebx                       /* Restore the GOT address */
> +	popl %ecx                       /* restore ecx */
> +#endif
> +
>  	/* Push address of our own entry points to .fini and .init.  */
>  	pushl _fini@GOT(%ebx)
>  	pushl _init@GOT(%ebx)
> diff --git a/libc/sysdeps/linux/x86_64/crt1.S b/libc/sysdeps/linux/x86_64/crt1.S
> index 87777dd5d..701cbf2f6 100644
> --- a/libc/sysdeps/linux/x86_64/crt1.S
> +++ b/libc/sysdeps/linux/x86_64/crt1.S
> @@ -80,6 +80,20 @@ _start:
>  	   the outermost frame obviously.  */
>  	xorl %ebp, %ebp
>  
> +#ifdef L_rcrt1
> +	pushq %rdi                          /* save rdi (but should be 0...) */
> +	pushq %rdx                          /* store rdx (rtld_fini) */
> +	xorq %rcx, %rcx                     /* ensure rcx is 0 */
> +	addq _start@GOTPCREL(%rip), %rcx    /* get offset of _start from beginning of file */
> +	movq _start@GOTPCREL(%rip), %rax    /* get run time address of _start */
> +	subq %rcx, %rax                     /* calculate run time load offset */
> +	movq %rax, %rdi                     /* load offset -> param 1 */
> +	call reloc_static_pie               /* relocate dynamic addrs */
> +	xorq %rax, %rax                     /* cleanup */
> +	popq %rdx
> +	popq %rdi
> +#endif
> +
>  	/* Extract the arguments as encoded on the stack and set up
>  	   the arguments for __libc_start_main (int (*main) (int, char **, char **),
>  		   int argc, char *argv,
> @@ -107,7 +121,7 @@ _start:
>  	   which grow downwards).  */
>  	pushq %rsp
>  
> -#if defined(L_Scrt1)
> +#if defined(L_Scrt1) || defined(L_rcrt1)
>  	/* Give address for main() */
>  	movq main@GOTPCREL(%rip), %rdi
>  
> diff --git a/libpthread/nptl/sysdeps/generic/Makefile.in b/libpthread/nptl/sysdeps/generic/Makefile.in
> index eb656ee17..a5ba9bbe8 100644
> --- a/libpthread/nptl/sysdeps/generic/Makefile.in
> +++ b/libpthread/nptl/sysdeps/generic/Makefile.in
> @@ -13,6 +13,10 @@ subdirs += libpthread/nptl/sysdeps/generic
>  libpthread_generic_DIR := $(top_srcdir)libpthread/nptl/sysdeps/generic
>  libpthread_generic_OUT := $(top_builddir)libpthread/nptl/sysdeps/generic
>  
> +ifeq ($(STATIC_PIE),y)
> +CFLAGS-libc-tls.c := -DSTATIC_PIE
> +endif
> +
>  libpthread_generic_libc_a_CSRC = libc-tls.c
>  libpthread_generic_libc_a_COBJ = $(patsubst %.c,$(libpthread_generic_OUT)/%.o,$(libpthread_generic_libc_a_CSRC))
>  libpthread_generic_libc_a_OBJS = $(libpthread_generic_libc_a_COBJ)
> diff --git a/libpthread/nptl/sysdeps/generic/libc-tls.c b/libpthread/nptl/sysdeps/generic/libc-tls.c
> index d746c9a38..0c8c558d0 100644
> --- a/libpthread/nptl/sysdeps/generic/libc-tls.c
> +++ b/libpthread/nptl/sysdeps/generic/libc-tls.c
> @@ -142,6 +142,10 @@ __libc_setup_tls (size_t tcbsize, size_t tcbalign)
>  	  initimage = (void *) &__tdata_start;
>  #else
>  	  initimage = (void *) phdr->p_vaddr;
> +#if !defined(SHARED) && defined(STATIC_PIE)
> +    extern ElfW(Addr) _dl_load_base;
> +    initimage += _dl_load_base;
> +#endif
>  #endif
>  	  align = phdr->p_align;
>  	  if (phdr->p_align > max_align)
> -- 
> 2.34.1
> 

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