musl/arch/arm/reloc.h

#include <endian.h>

#if __BYTE_ORDER == __BIG_ENDIAN
#define ENDIAN_SUFFIX "eb"
#else
#define ENDIAN_SUFFIX ""
#endif

#if __SOFTFP__
#define FP_SUFFIX ""
#else
#define FP_SUFFIX "hf"
#endif

#define LDSO_ARCH "arm" ENDIAN_SUFFIX FP_SUFFIX

#define NO_LEGACY_INITFINI

#define TPOFF_K 8

#define REL_SYMBOLIC    R_ARM_ABS32
#define REL_GOT         R_ARM_GLOB_DAT
#define REL_PLT         R_ARM_JUMP_SLOT
#define REL_RELATIVE    R_ARM_RELATIVE
#define REL_COPY        R_ARM_COPY
#define REL_DTPMOD      R_ARM_TLS_DTPMOD32
#define REL_DTPOFF      R_ARM_TLS_DTPOFF32
#define REL_TPOFF       R_ARM_TLS_TPOFF32
//#define REL_TLSDESC     R_ARM_TLS_DESC

#define CRTJMP(pc,sp) __asm__ __volatile__( \
	"mov sp,%1 ; tst %0,#1 ; moveq pc,%0 ; bx %0" : : "r"(pc), "r"(sp) : "memory" )
make the dynamic linker find its path file relative to its own location prior to this change, using a non-default syslibdir was impractical on systems where the ordinary library paths contain musl-incompatible library files. the file containing search paths was always taken from /etc, which would either correspond to a system-wide musl installation, or fail to exist at all, resulting in searching of the default library path. the new search strategy is safe even for suid programs because the pathname used comes from the PT_INTERP header of the program being run, rather than any external input. as part of this change, I have also begun differentiating the names of arch variants that differ by endianness or floating point calling convention. the corresponding changes in the build system and and gcc wrapper script (to use an alternate dynamic linker name) for these configurations have not yet been made. 2013-07-18 23:29:44 +00:00			`#include <endian.h>`
first attempt at arm dynamic linking 2011-10-01 04:52:33 +00:00
make the dynamic linker find its path file relative to its own location prior to this change, using a non-default syslibdir was impractical on systems where the ordinary library paths contain musl-incompatible library files. the file containing search paths was always taken from /etc, which would either correspond to a system-wide musl installation, or fail to exist at all, resulting in searching of the default library path. the new search strategy is safe even for suid programs because the pathname used comes from the PT_INTERP header of the program being run, rather than any external input. as part of this change, I have also begun differentiating the names of arch variants that differ by endianness or floating point calling convention. the corresponding changes in the build system and and gcc wrapper script (to use an alternate dynamic linker name) for these configurations have not yet been made. 2013-07-18 23:29:44 +00:00			`#if __BYTE_ORDER == __BIG_ENDIAN`
			`#define ENDIAN_SUFFIX "eb"`
			`#else`
			`#define ENDIAN_SUFFIX ""`
			`#endif`

			`#if __SOFTFP__`
			`#define FP_SUFFIX ""`
			`#else`
			`#define FP_SUFFIX "hf"`
			`#endif`

			`#define LDSO_ARCH "arm" ENDIAN_SUFFIX FP_SUFFIX`
first attempt at arm dynamic linking 2011-10-01 04:52:33 +00:00
refactor to remove arch-specific relocation code from dynamic linker this was one of the main instances of ugly code duplication: all archs use basically the same types of relocations, but roughly equivalent logic was duplicated for each arch to account for the different naming and numbering of relocation types and variation in whether REL or RELA records are used. as an added bonus, both REL and RELA are now supported on all archs, regardless of which is used by the standard toolchain. 2014-06-18 06:44:02 +00:00			`#define NO_LEGACY_INITFINI`

			`#define TPOFF_K 8`
first attempt at arm dynamic linking 2011-10-01 04:52:33 +00:00
dynamic linker bootstrap overhaul this overhaul further reduces the amount of arch-specific code needed by the dynamic linker and removes a number of assumptions, including: - that symbolic function references inside libc are bound at link time via the linker option -Bsymbolic-functions. - that libc functions used by the dynamic linker do not require access to data symbols. - that static/internal function calls and data accesses can be made without performing any relocations, or that arch-specific startup code handled any such relocations needed. removing these assumptions paves the way for allowing libc.so itself to be built with stack protector (among other things), and is achieved by a three-stage bootstrap process: 1. relative relocations are processed with a flat function. 2. symbolic relocations are processed with no external calls/data. 3. main program and dependency libs are processed with a fully-functional libc/ldso. reduction in arch-specific code is achived through the following: - crt_arch.h, used for generating crt1.o, now provides the entry point for the dynamic linker too. - asm is no longer responsible for skipping the beginning of argv[] when ldso is invoked as a command. - the functionality previously provided by __reloc_self for heavily GOT-dependent RISC archs is now the arch-agnostic stage-1. - arch-specific relocation type codes are mapped directly as macros rather than via an inline translation function/switch statement. 2015-04-13 06:56:26 +00:00			`#define REL_SYMBOLIC R_ARM_ABS32`
			`#define REL_GOT R_ARM_GLOB_DAT`
			`#define REL_PLT R_ARM_JUMP_SLOT`
			`#define REL_RELATIVE R_ARM_RELATIVE`
			`#define REL_COPY R_ARM_COPY`
			`#define REL_DTPMOD R_ARM_TLS_DTPMOD32`
			`#define REL_DTPOFF R_ARM_TLS_DTPOFF32`
			`#define REL_TPOFF R_ARM_TLS_TPOFF32`
			`//#define REL_TLSDESC R_ARM_TLS_DESC`

			`#define CRTJMP(pc,sp) __asm__ __volatile__( \`
			`"mov sp,%1 ; tst %0,#1 ; moveq pc,%0 ; bx %0" : : "r"(pc), "r"(sp) : "memory" )`