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/* 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)
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