diff options
Diffstat (limited to 'libc/sysdeps/linux/xtensa/makecontext.c')
| -rw-r--r-- | libc/sysdeps/linux/xtensa/makecontext.c | 179 |
1 files changed, 179 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/xtensa/makecontext.c b/libc/sysdeps/linux/xtensa/makecontext.c new file mode 100644 index 000000000..da26a0130 --- /dev/null +++ b/libc/sysdeps/linux/xtensa/makecontext.c @@ -0,0 +1,179 @@ +/* Copyright (C) 2018 - 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 + <http://www.gnu.org/licenses/>. */ + +#include <sysdep.h> +#include <stdarg.h> +#include <stdint.h> +#include <string.h> +#include <ucontext.h> + +extern void __start_context (void); + +#if defined(__XTENSA_CALL0_ABI__) +/* + * makecontext sets up new stack like this: + * + * +------------------ stack top (uc_stack.ss_sp + uc_stack.ss_size) + * | optional alignment + * +------------------ CFA of __start_context, initial sp points here + * | optional padding + * +------------------ Optional arguments 6..argc - 1 + * | func arg argc - 1 + * | func arg argc - 2 + * | ... + * | func arg 6 + * +------------------ Optional arguments 2..5 + * | func arg 5 + * 16 | func arg 4 + * | func arg 3 + * | func arg 2 + * +------------------ Optional arguments 0..1 + * | func arg 1 + * 16 | func arg 0 + * | padding + * | padding + * +------------------ CFA of pseudo getcontext + * | + * +------------------ stack bottom (uc_stack.ss_sp) + * + * When argc is 0 arguments areas are not allocated, + * when 1 <= argc < 3 only area for arguments 0..1 is allocated, + * when 3 <= argc < 7 areas for arguments 0..1 and 2..5 is allocated, + * when argc >= 7 all three arguments areas are allocated. + * Arguments 0..5 area is deallocated by the __start_context after + * arguments are loaded into registers. + * uc_mcontext registers are set as if __start_context made call0 + * to getcontext, sp points to that pseudo getcontext CFA. + * setcontext/swapcontext will arrange for restoring regiters + * a1, a12..a15 of __start_context. + */ + +void +__makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...) +{ + unsigned long sp = ((unsigned long) ucp->uc_stack.ss_sp + + ucp->uc_stack.ss_size) & -16; + int i; + + if (argc > 0) + sp -= 4 * (argc + 2); + sp &= -16; + + ucp->uc_mcontext.sc_pc = (unsigned long) __start_context; + ucp->uc_mcontext.sc_a[1] = sp; + ucp->uc_mcontext.sc_a[12] = (unsigned long) func; + ucp->uc_mcontext.sc_a[13] = (unsigned long) ucp->uc_link; + ucp->uc_mcontext.sc_a[14] = argc; + + if (argc) + { + va_list ap; + + va_start (ap, argc); + for (i = 0; i < argc; ++i) + ((int *) sp)[i + 2] = va_arg (ap, int); + va_end (ap); + } +} +#elif defined(__XTENSA_WINDOWED_ABI__) +/* + * makecontext sets up new stack like this: + * + * +------------------ stack top (uc_stack.ss_sp + uc_stack.ss_size) + * | optional alignment + * +------------------ CFA of __start_context + * 16 | Outermost caller spill area + * +------------------ + * 16 | __start_context overflow area + * +------------------ initial sp points here + * | optional padding + * +------------------ Optional arguments 6..argc - 1 + * | func arg argc - 1 + * | func arg argc - 2 + * | ... + * | func arg 6 + * +------------------ Optional arguments 3..5 + * | func arg 5 + * 16 | func arg 4 + * | func arg 3 + * | padding + * +------------------ CFA of pseudo getcontext + * 16 | __start_context caller spill area + * +------------------ + * | + * +------------------ stack bottom (uc_stack.ss_sp) + * + * When argc < 4 both arguments areas are not allocated, + * when 4 <= argc < 7 only area for arguments 3..5 is allocated, + * when argc >= 7 both arguments areas are allocated. + * Arguments 3..5 area is deallocated by the __start_context after + * arguments are loaded into registers. + * uc_mcontext registers are set as if __start_context made call8 + * to getcontext, sp points to that pseudo getcontext CFA, spill + * area under that sp has a1 pointing to the __start_context CFA + * at the top of the stack. setcontext/swapcontext will arrange for + * restoring regiters a0..a7 of __start_context. + */ + +void +__makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...) +{ + unsigned long sp = ((unsigned long) ucp->uc_stack.ss_sp + + ucp->uc_stack.ss_size - 32) & -16; + unsigned long spill0[4] = + { + 0, sp + 32, 0, 0, + }; + int i; + + memset ((void *) sp, 0, 32); + + if (argc > 2) + sp -= 4 * (argc - 2); + sp &= -16; + + ucp->uc_mcontext.sc_pc = + ((unsigned long) __start_context & 0x3fffffff) + 0x80000000; + ucp->uc_mcontext.sc_a[0] = 0; + ucp->uc_mcontext.sc_a[1] = sp; + ucp->uc_mcontext.sc_a[2] = (unsigned long) func; + ucp->uc_mcontext.sc_a[3] = (unsigned long) ucp->uc_link; + ucp->uc_mcontext.sc_a[4] = argc; + + if (argc) + { + va_list ap; + + va_start (ap, argc); + for (i = 0; i < argc; ++i) + { + if (i < 3) + ucp->uc_mcontext.sc_a[5 + i] = va_arg (ap, int); + else + ((int *) sp)[i - 2] = va_arg (ap, int); + } + va_end (ap); + } + + sp -= 16; + memcpy ((void *) sp, spill0, sizeof (spill0)); +} +#else +#error Unsupported Xtensa ABI +#endif + +weak_alias (__makecontext, makecontext) |