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8f7fafebd1
The environ is retrieved from the _start code and is easy to store at this moment. Let's declare the variable weak and store the value into it. By not being static it will be visible to all units. By being weak, if some programs already declared it, they will continue to be able to use it. This was tested with mips24kc (BE) both with environ inherited from _start and extracted from envp. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
213 lines
11 KiB
C
213 lines
11 KiB
C
/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
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/*
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* MIPS specific definitions for NOLIBC
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* Copyright (C) 2017-2022 Willy Tarreau <w@1wt.eu>
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*/
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#ifndef _NOLIBC_ARCH_MIPS_H
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#define _NOLIBC_ARCH_MIPS_H
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/* The struct returned by the stat() syscall. 88 bytes are returned by the
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* syscall.
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*/
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struct sys_stat_struct {
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unsigned int st_dev;
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long st_pad1[3];
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unsigned long st_ino;
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unsigned int st_mode;
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unsigned int st_nlink;
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unsigned int st_uid;
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unsigned int st_gid;
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unsigned int st_rdev;
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long st_pad2[2];
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long st_size;
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long st_pad3;
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long st_atime;
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long st_atime_nsec;
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long st_mtime;
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long st_mtime_nsec;
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long st_ctime;
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long st_ctime_nsec;
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long st_blksize;
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long st_blocks;
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long st_pad4[14];
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};
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/* Syscalls for MIPS ABI O32 :
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* - WARNING! there's always a delayed slot!
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* - WARNING again, the syntax is different, registers take a '$' and numbers
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* do not.
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* - registers are 32-bit
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* - stack is 8-byte aligned
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* - syscall number is passed in v0 (starts at 0xfa0).
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* - arguments are in a0, a1, a2, a3, then the stack. The caller needs to
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* leave some room in the stack for the callee to save a0..a3 if needed.
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* - Many registers are clobbered, in fact only a0..a2 and s0..s8 are
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* preserved. See: https://www.linux-mips.org/wiki/Syscall as well as
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* scall32-o32.S in the kernel sources.
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* - the system call is performed by calling "syscall"
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* - syscall return comes in v0, and register a3 needs to be checked to know
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* if an error occurred, in which case errno is in v0.
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* - the arguments are cast to long and assigned into the target registers
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* which are then simply passed as registers to the asm code, so that we
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* don't have to experience issues with register constraints.
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*/
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#define my_syscall0(num) \
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({ \
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register long _num __asm__ ("v0") = (num); \
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register long _arg4 __asm__ ("a3"); \
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\
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__asm__ volatile ( \
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"addiu $sp, $sp, -32\n" \
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"syscall\n" \
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"addiu $sp, $sp, 32\n" \
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: "=r"(_num), "=r"(_arg4) \
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: "r"(_num) \
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: "memory", "cc", "at", "v1", "hi", "lo", \
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"t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \
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); \
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_arg4 ? -_num : _num; \
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})
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#define my_syscall1(num, arg1) \
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({ \
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register long _num __asm__ ("v0") = (num); \
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register long _arg1 __asm__ ("a0") = (long)(arg1); \
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register long _arg4 __asm__ ("a3"); \
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\
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__asm__ volatile ( \
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"addiu $sp, $sp, -32\n" \
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"syscall\n" \
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"addiu $sp, $sp, 32\n" \
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: "=r"(_num), "=r"(_arg4) \
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: "0"(_num), \
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"r"(_arg1) \
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: "memory", "cc", "at", "v1", "hi", "lo", \
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"t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \
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); \
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_arg4 ? -_num : _num; \
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})
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#define my_syscall2(num, arg1, arg2) \
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({ \
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register long _num __asm__ ("v0") = (num); \
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register long _arg1 __asm__ ("a0") = (long)(arg1); \
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register long _arg2 __asm__ ("a1") = (long)(arg2); \
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register long _arg4 __asm__ ("a3"); \
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\
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__asm__ volatile ( \
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"addiu $sp, $sp, -32\n" \
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"syscall\n" \
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"addiu $sp, $sp, 32\n" \
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: "=r"(_num), "=r"(_arg4) \
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: "0"(_num), \
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"r"(_arg1), "r"(_arg2) \
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: "memory", "cc", "at", "v1", "hi", "lo", \
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"t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \
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); \
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_arg4 ? -_num : _num; \
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})
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#define my_syscall3(num, arg1, arg2, arg3) \
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({ \
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register long _num __asm__ ("v0") = (num); \
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register long _arg1 __asm__ ("a0") = (long)(arg1); \
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register long _arg2 __asm__ ("a1") = (long)(arg2); \
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register long _arg3 __asm__ ("a2") = (long)(arg3); \
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register long _arg4 __asm__ ("a3"); \
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\
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__asm__ volatile ( \
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"addiu $sp, $sp, -32\n" \
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"syscall\n" \
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"addiu $sp, $sp, 32\n" \
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: "=r"(_num), "=r"(_arg4) \
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: "0"(_num), \
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"r"(_arg1), "r"(_arg2), "r"(_arg3) \
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: "memory", "cc", "at", "v1", "hi", "lo", \
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"t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \
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); \
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_arg4 ? -_num : _num; \
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})
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#define my_syscall4(num, arg1, arg2, arg3, arg4) \
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({ \
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register long _num __asm__ ("v0") = (num); \
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register long _arg1 __asm__ ("a0") = (long)(arg1); \
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register long _arg2 __asm__ ("a1") = (long)(arg2); \
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register long _arg3 __asm__ ("a2") = (long)(arg3); \
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register long _arg4 __asm__ ("a3") = (long)(arg4); \
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\
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__asm__ volatile ( \
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"addiu $sp, $sp, -32\n" \
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"syscall\n" \
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"addiu $sp, $sp, 32\n" \
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: "=r" (_num), "=r"(_arg4) \
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: "0"(_num), \
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"r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4) \
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: "memory", "cc", "at", "v1", "hi", "lo", \
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"t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \
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); \
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_arg4 ? -_num : _num; \
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})
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#define my_syscall5(num, arg1, arg2, arg3, arg4, arg5) \
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({ \
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register long _num __asm__ ("v0") = (num); \
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register long _arg1 __asm__ ("a0") = (long)(arg1); \
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register long _arg2 __asm__ ("a1") = (long)(arg2); \
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register long _arg3 __asm__ ("a2") = (long)(arg3); \
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register long _arg4 __asm__ ("a3") = (long)(arg4); \
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register long _arg5 = (long)(arg5); \
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\
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__asm__ volatile ( \
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"addiu $sp, $sp, -32\n" \
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"sw %7, 16($sp)\n" \
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"syscall\n " \
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"addiu $sp, $sp, 32\n" \
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: "=r" (_num), "=r"(_arg4) \
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: "0"(_num), \
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"r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5) \
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: "memory", "cc", "at", "v1", "hi", "lo", \
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"t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9" \
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); \
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_arg4 ? -_num : _num; \
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})
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char **environ __attribute__((weak));
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/* startup code, note that it's called __start on MIPS */
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void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) __start(void)
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{
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__asm__ volatile (
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//".set nomips16\n"
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".set push\n"
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".set noreorder\n"
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".option pic0\n"
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//".ent __start\n"
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//"__start:\n"
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"lw $a0,($sp)\n" // argc was in the stack
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"addiu $a1, $sp, 4\n" // argv = sp + 4
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"sll $a2, $a0, 2\n" // a2 = argc * 4
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"add $a2, $a2, $a1\n" // envp = argv + 4*argc ...
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"addiu $a2, $a2, 4\n" // ... + 4
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"lui $a3, %hi(environ)\n" // load environ into a3 (hi)
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"addiu $a3, %lo(environ)\n" // load environ into a3 (lo)
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"sw $a2,($a3)\n" // store envp(a2) into environ
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"li $t0, -8\n"
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"and $sp, $sp, $t0\n" // sp must be 8-byte aligned
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"addiu $sp,$sp,-16\n" // the callee expects to save a0..a3 there!
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"jal main\n" // main() returns the status code, we'll exit with it.
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"nop\n" // delayed slot
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"move $a0, $v0\n" // retrieve 32-bit exit code from v0
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"li $v0, 4001\n" // NR_exit == 4001
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"syscall\n"
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//".end __start\n"
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".set pop\n"
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);
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__builtin_unreachable();
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}
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#endif // _NOLIBC_ARCH_MIPS_H
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