riscv/musl - musl - Gitea: Git with a cup of tea

Alex Dowad 35b3312b6f Build process uses script to add CFI directives to x86 asm Some functions implemented in asm need to use EBP for purposes other than acting as a frame pointer. (Notably, it is used for the 6th argument to syscalls with 6 arguments.) Without frame pointers, GDB can only show backtraces if it gets CFI information from a .debug_frame or .eh_frame ELF section. Rather than littering our asm with ugly .cfi directives, use an awk script to insert them in the right places during the build process, so GDB can keep track of where the current stack frame is relative to the stack pointer. This means GDB can produce beautiful stack traces at any given point when single-stepping through asm functions. Additionally, when registers are saved on the stack and later overwritten, emit ..cfi directives so GDB will know where they were saved relative to the stack pointer. This way, when you look back up the stack from within an asm function, you can still reliably print the values of local variables in the caller. If this awk script were to understand every possible wild and crazy contortion that an asm programmer can do with the stack and registers, and always emit the exact ..cfi directives needed for GDB to know what the register values were in the preceding stack frame, it would necessarily be as complex as a full x86 emulator. That way lies madness. Hence, we assume that the stack pointer will _only_ ever be adjusted using push/pop or else add/sub with a constant. We do not attempt to detect every possible way that a register value could be saved for later use, just the simple and common ways. Thanks to Szabolcs Nagy for suggesting numerous improvements to this code.		11 years ago
arch	mitigate performance regression in libc-internal locks on x86_64	11 years ago
crt	add rcrt1 start file for fully static-linked PIE	11 years ago
dist	add another example option to dist/config.mak	14 years ago
include	socket.h: fix SO_* for mips	11 years ago
lib	new solution for empty lib dir (old one had some problems)	15 years ago
src	getsubopt: don't include leading = in value string	11 years ago
tools	Build process uses script to add CFI directives to x86 asm	11 years ago
.gitignore	add musl-clang, a wrapper for system clang installs	11 years ago
COPYRIGHT	update authors/contributors list	11 years ago
INSTALL	update notice on broken gcc versions in INSTALL file	12 years ago
Makefile	Build process uses script to add CFI directives to x86 asm	11 years ago
README	update version reference in the README file	12 years ago
VERSION	release 1.1.10	11 years ago
WHATSNEW	release 1.1.10	11 years ago
configure	Build process uses script to add CFI directives to x86 asm	11 years ago

README


    musl libc

musl, pronounced like the word "mussel", is an MIT-licensed
implementation of the standard C library targetting the Linux syscall
API, suitable for use in a wide range of deployment environments. musl
offers efficient static and dynamic linking support, lightweight code
and low runtime overhead, strong fail-safe guarantees under correct
usage, and correctness in the sense of standards conformance and
safety. musl is built on the principle that these goals are best
achieved through simple code that is easy to understand and maintain.

The 1.1 release series for musl features coverage for all interfaces
defined in ISO C99 and POSIX 2008 base, along with a number of
non-standardized interfaces for compatibility with Linux, BSD, and
glibc functionality.

For basic installation instructions, see the included INSTALL file.
Information on full musl-targeted compiler toolchains, system
bootstrapping, and Linux distributions built on musl can be found on
the project website:

    http://www.musl-libc.org/