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[uclibc-ng-devel] Added support for creation of Static Position-Independent Executable (PIE) on aarch64

Message ID CANP1oa1RhjC7BMZav4tKaeWF6tuZV4xQW6GQ+ToQe+2NLHVmNw@mail.gmail.com
State New
Headers show
Series [uclibc-ng-devel] Added support for creation of Static Position-Independent Executable (PIE) on aarch64 | expand

Commit Message

linted July 28, 2022, 2 p.m. UTC
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@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@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 mbox series

Patch

From b55075957b6a95e120095fb5d5dcc96bd500749e Mon Sep 17 00:00:00 2001
From: linted <linted@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@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