diff options
| author | Max Filippov <jcmvbkbc@gmail.com> | 2024-06-01 03:39:03 -0700 |
|---|---|---|
| committer | Waldemar Brodkorb <wbx@openadk.org> | 2024-06-04 16:40:42 +0200 |
| commit | 138274e92a01be8a98392489b1a2f497ab11c201 (patch) | |
| tree | f0be841a1e915e86d4215326a13654f8034632a4 /libc/sysdeps/linux/xtensa/crt1.S | |
| parent | 8bb33a2e1f2baec2078581d77e181f1ead5f51aa (diff) | |
xtensa: add FDPIC support
This change implements Xtensa FDPIC ABI as specified in the first
version of the following document:
https://github.com/jcmvbkbc/xtensa-abi/blob/master/fdpic-xtensa.txt
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Diffstat (limited to 'libc/sysdeps/linux/xtensa/crt1.S')
| -rw-r--r-- | libc/sysdeps/linux/xtensa/crt1.S | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/xtensa/crt1.S b/libc/sysdeps/linux/xtensa/crt1.S index 3fa14ae58..a12f82dd6 100644 --- a/libc/sysdeps/linux/xtensa/crt1.S +++ b/libc/sysdeps/linux/xtensa/crt1.S @@ -35,6 +35,86 @@ #include <features.h> +#if defined(__FDPIC__) + +/* This is the canonical entry point, usually the first thing in the text + segment. When the entry point runs, most register values are unspecified, + except for: + + a6 Address of .dynamic section + a5 Interpreter map + a4 Executable map + + a2 Contains a function pointer to be registered with `atexit'. + This is how the dynamic linker arranges to have DT_FINI + functions called for shared libraries that have been loaded + before this code runs. + + a1 The stack (i.e., a1+16) contains the arguments and environment: + a1+0 argc + a1+4 argv[0] + ... + a1+(4*argc) NULL + a1+(4*(argc+1)) envp[0] + ... + NULL + */ + .text + .align 4 + .literal_position + .global _start + .type _start, @function +_start: +#if defined(__XTENSA_CALL0_ABI__) + + .begin no-transform + call0 1f +2: + .end no-transform + .align 4 + .literal_position +1: + movi a15, 2b + sub a15, a0, a15 + + mov a12, a4 + mov a13, a5 + mov a14, a6 + mov a2, a4 + movi a3, __ROFIXUP_LIST__ + add a3, a3, a15 + movi a4, __ROFIXUP_END__ + add a4, a4, a15 + movi a0, __self_reloc + add a0, a0, a15 + callx0 a0 + + mov a11, a2 + movi a2, main@GOTOFFFUNCDESC + add a2, a2, a11 + l32i a3, sp, 0 /* argc */ + addi a4, sp, 4 /* argv */ + /* a5 is either 0 when static or set by the RTLD to the rtld_fini */ + mov a7, a13 + /* unused stack_end argument is what used to be argc */ + movi a5, _init@GOTOFFFUNCDESC + add a5, a5, a11 + movi a6, _fini@GOTOFFFUNCDESC + add a6, a6, a11 + + movi a0, __uClibc_main@GOTOFFFUNCDESC + add a0, a0, a11 + l32i a11, a0, 4 + l32i a0, a0, 0 + callx0 a0 + ill + +#else +#error Unsupported Xtensa ABI +#endif + +#else /* defined(__FDPIC__) */ + #ifndef __UCLIBC_CTOR_DTOR__ .weak _init .weak _fini @@ -173,3 +253,4 @@ __data_start: .long 0 .weak data_start data_start = __data_start +#endif /* defined(__FDPIC__) */ |