mirror of
https://github.com/opencontainers/runc.git
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Rodrigo Campos
90f5da651a
Linux repo has under `tools/include/nolibc` very simple include files that we can use to generate very small binaries that don't depend on libc. To make things even better, since Linux 6.6 it supports all the architectures we support in runc, which is just beautiful. The runc-dmz binary on x86_64 before this patch (on my debian host) was taking 636K, with this patch it takes only 8K. Signed-off-by: Rodrigo Campos <rodrigoca@microsoft.com>
196 lines
10 KiB
C
196 lines
10 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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#include "compiler.h"
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#include "crt.h"
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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 _NOLIBC_SYSCALL_CLOBBERLIST \
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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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#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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: _NOLIBC_SYSCALL_CLOBBERLIST \
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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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: _NOLIBC_SYSCALL_CLOBBERLIST \
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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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: _NOLIBC_SYSCALL_CLOBBERLIST \
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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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: _NOLIBC_SYSCALL_CLOBBERLIST \
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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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: _NOLIBC_SYSCALL_CLOBBERLIST \
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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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: _NOLIBC_SYSCALL_CLOBBERLIST \
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); \
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_arg4 ? -_num : _num; \
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})
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#define my_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \
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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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register long _arg6 = (long)(arg6); \
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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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"sw %8, 20($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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"r"(_arg6) \
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: _NOLIBC_SYSCALL_CLOBBERLIST \
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); \
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_arg4 ? -_num : _num; \
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})
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/* startup code, note that it's called __start on MIPS */
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void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector __start(void)
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{
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__asm__ volatile (
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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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"move $a0, $sp\n" /* save stack pointer to $a0, as arg1 of _start_c */
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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 _start_c\n" /* transfer to c runtime */
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" nop\n" /* delayed slot */
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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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