/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
/*
* ARM specific definitions for NOLIBC
* Copyright (C) 2017-2022 Willy Tarreau <w@1wt.eu>
*/
#ifndef _NOLIBC_ARCH_ARM_H
#define _NOLIBC_ARCH_ARM_H
#include "compiler.h"
/* The struct returned by the stat() syscall, 32-bit only, the syscall returns
* exactly 56 bytes (stops before the unused array). In big endian, the format
* differs as devices are returned as short only.
*/
struct sys_stat_struct {
#if defined(__ARMEB__)
unsigned short st_dev;
unsigned short __pad1;
#else
unsigned long st_dev;
#endif
unsigned long st_ino;
unsigned short st_mode;
unsigned short st_nlink;
unsigned short st_uid;
unsigned short st_gid;
#if defined(__ARMEB__)
unsigned short st_rdev;
unsigned short __pad2;
#else
unsigned long st_rdev;
#endif
unsigned long st_size;
unsigned long st_blksize;
unsigned long st_blocks;
unsigned long st_atime;
unsigned long st_atime_nsec;
unsigned long st_mtime;
unsigned long st_mtime_nsec;
unsigned long st_ctime;
unsigned long st_ctime_nsec;
unsigned long __unused[2];
};
/* Syscalls for ARM in ARM or Thumb modes :
* - registers are 32-bit
* - stack is 8-byte aligned
* ( http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.faqs/ka4127.html)
* - syscall number is passed in r7
* - arguments are in r0, r1, r2, r3, r4, r5
* - the system call is performed by calling svc #0
* - syscall return comes in r0.
* - only lr is clobbered.
* - the arguments are cast to long and assigned into the target registers
* which are then simply passed as registers to the asm code, so that we
* don't have to experience issues with register constraints.
* - the syscall number is always specified last in order to allow to force
* some registers before (gcc refuses a %-register at the last position).
* - in thumb mode without -fomit-frame-pointer, r7 is also used to store the
* frame pointer, and we cannot directly assign it as a register variable,
* nor can we clobber it. Instead we assign the r6 register and swap it
* with r7 before calling svc, and r6 is marked as clobbered.
* We're just using any regular register which we assign to r7 after saving
* it.
*
* Also, ARM supports the old_select syscall if newselect is not available
*/
#define __ARCH_WANT_SYS_OLD_SELECT
#if (defined(__THUMBEB__) || defined(__THUMBEL__)) && \
!defined(NOLIBC_OMIT_FRAME_POINTER)
/* swap r6,r7 needed in Thumb mode since we can't use nor clobber r7 */
#define _NOLIBC_SYSCALL_REG "r6"
#define _NOLIBC_THUMB_SET_R7 "eor r7, r6\neor r6, r7\neor r7, r6\n"
#define _NOLIBC_THUMB_RESTORE_R7 "mov r7, r6\n"
#else /* we're in ARM mode */
/* in Arm mode we can directly use r7 */
#define _NOLIBC_SYSCALL_REG "r7"
#define _NOLIBC_THUMB_SET_R7 ""
#define _NOLIBC_THUMB_RESTORE_R7 ""
#endif /* end THUMB */
#define my_syscall0(num) \
({ \
register long _num __asm__(_NOLIBC_SYSCALL_REG) = (num); \
register long _arg1 __asm__ ("r0"); \
\
__asm__ volatile ( \
_NOLIBC_THUMB_SET_R7 \
"svc #0\n" \
_NOLIBC_THUMB_RESTORE_R7 \
: "=r"(_arg1), "=r"(_num) \
: "r"(_arg1), \
"r"(_num) \
: "memory", "cc", "lr" \
); \
_arg1; \
})
#define my_syscall1(num, arg1) \
({ \
register long _num __asm__(_NOLIBC_SYSCALL_REG) = (num); \
register long _arg1 __asm__ ("r0") = (long)(arg1); \
\
__asm__ volatile ( \
_NOLIBC_THUMB_SET_R7 \
"svc #0\n" \
_NOLIBC_THUMB_RESTORE_R7 \
: "=r"(_arg1), "=r" (_num) \
: "r"(_arg1), \
"r"(_num) \
: "memory", "cc", "lr" \
); \
_arg1; \
})
#define my_syscall2(num, arg1, arg2) \
({ \
register long _num __asm__(_NOLIBC_SYSCALL_REG) = (num); \
register long _arg1 __asm__ ("r0") = (long)(arg1); \
register long _arg2 __asm__ ("r1") = (long)(arg2); \
\
__asm__ volatile ( \
_NOLIBC_THUMB_SET_R7 \
"svc #0\n" \
_NOLIBC_THUMB_RESTORE_R7 \
: "=r"(_arg1), "=r" (_num) \
: "r"(_arg1), "r"(_arg2), \
"r"(_num) \
: "memory", "cc", "lr" \
); \
_arg1; \
})
#define my_syscall3(num, arg1, arg2, arg3) \
({ \
register long _num __asm__(_NOLIBC_SYSCALL_REG) = (num); \
register long _arg1 __asm__ ("r0") = (long)(arg1); \
register long _arg2 __asm__ ("r1") = (long)(arg2); \
register long _arg3 __asm__ ("r2") = (long)(arg3); \
\
__asm__ volatile ( \
_NOLIBC_THUMB_SET_R7 \
"svc #0\n" \
_NOLIBC_THUMB_RESTORE_R7 \
: "=r"(_arg1), "=r" (_num) \
: "r"(_arg1), "r"(_arg2), "r"(_arg3), \
"r"(_num) \
: "memory", "cc", "lr" \
); \
_arg1; \
})
#define my_syscall4(num, arg1, arg2, arg3, arg4) \
({ \
register long _num __asm__(_NOLIBC_SYSCALL_REG) = (num); \
register long _arg1 __asm__ ("r0") = (long)(arg1); \
register long _arg2 __asm__ ("r1") = (long)(arg2); \
register long _arg3 __asm__ ("r2") = (long)(arg3); \
register long _arg4 __asm__ ("r3") = (long)(arg4); \
\
__asm__ volatile ( \
_NOLIBC_THUMB_SET_R7 \
"svc #0\n" \
_NOLIBC_THUMB_RESTORE_R7 \
: "=r"(_arg1), "=r" (_num) \
: "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), \
"r"(_num) \
: "memory", "cc", "lr" \
); \
_arg1; \
})
#define my_syscall5(num, arg1, arg2, arg3, arg4, arg5) \
({ \
register long _num __asm__(_NOLIBC_SYSCALL_REG) = (num); \
register long _arg1 __asm__ ("r0") = (long)(arg1); \
register long _arg2 __asm__ ("r1") = (long)(arg2); \
register long _arg3 __asm__ ("r2") = (long)(arg3); \
register long _arg4 __asm__ ("r3") = (long)(arg4); \
register long _arg5 __asm__ ("r4") = (long)(arg5); \
\
__asm__ volatile ( \
_NOLIBC_THUMB_SET_R7 \
"svc #0\n" \
_NOLIBC_THUMB_RESTORE_R7 \
: "=r"(_arg1), "=r" (_num) \
: "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \
"r"(_num) \
: "memory", "cc", "lr" \
); \
_arg1; \
})
#define my_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \
({ \
register long _num __asm__(_NOLIBC_SYSCALL_REG) = (num); \
register long _arg1 __asm__ ("r0") = (long)(arg1); \
register long _arg2 __asm__ ("r1") = (long)(arg2); \
register long _arg3 __asm__ ("r2") = (long)(arg3); \
register long _arg4 __asm__ ("r3") = (long)(arg4); \
register long _arg5 __asm__ ("r4") = (long)(arg5); \
register long _arg6 __asm__ ("r5") = (long)(arg6); \
\
__asm__ volatile ( \
_NOLIBC_THUMB_SET_R7 \
"svc #0\n" \
_NOLIBC_THUMB_RESTORE_R7 \
: "=r"(_arg1), "=r" (_num) \
: "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \
"r"(_arg6), "r"(_num) \
: "memory", "cc", "lr" \
); \
_arg1; \
})
char **environ __attribute__((weak));
const unsigned long *_auxv __attribute__((weak));
/* startup code */
void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) __no_stack_protector _start(void)
{
__asm__ volatile (
#ifdef _NOLIBC_STACKPROTECTOR
"bl __stack_chk_init\n" /* initialize stack protector */
#endif
"pop {%r0}\n" /* argc was in the stack */
"mov %r1, %sp\n" /* argv = sp */
"add %r2, %r0, $1\n" /* envp = (argc + 1) ... */
"lsl %r2, %r2, $2\n" /* * 4 ... */
"add %r2, %r2, %r1\n" /* + argv */
"ldr %r3, 1f\n" /* r3 = &environ (see below) */
"str %r2, [r3]\n" /* store envp into environ */
"mov r4, r2\n" /* search for auxv (follows NULL after last env) */
"0:\n"
"mov r5, r4\n" /* r5 = r4 */
"add r4, r4, #4\n" /* r4 += 4 */
"ldr r5,[r5]\n" /* r5 = *r5 = *(r4-4) */
"cmp r5, #0\n" /* and stop at NULL after last env */
"bne 0b\n"
"ldr %r3, 2f\n" /* r3 = &_auxv (low bits) */
"str r4, [r3]\n" /* store r4 into _auxv */
"mov %r3, $8\n" /* AAPCS : sp must be 8-byte aligned in the */
"neg %r3, %r3\n" /* callee, and bl doesn't push (lr=pc) */
"and %r3, %r3, %r1\n" /* so we do sp = r1(=sp) & r3(=-8); */
"mov %sp, %r3\n"
"bl main\n" /* main() returns the status code, we'll exit with it. */
"movs r7, $1\n" /* NR_exit == 1 */
"svc $0x00\n"
".align 2\n" /* below are the pointers to a few variables */
"1:\n"
".word environ\n"
"2:\n"
".word _auxv\n"
);
__builtin_unreachable();
}
#endif /* _NOLIBC_ARCH_ARM_H */