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glibc/sysdeps/unix/sysv/linux/m68k/sysdep.h
Florian Weimer 88f4b6929c Introduce <pointer_guard.h>, extracted from <sysdep.h> 
This allows us to define a generic no-op version of PTR_MANGLE and
PTR_DEMANGLE.  In the future, we can use PTR_MANGLE and PTR_DEMANGLE
unconditionally in C sources, avoiding an unintended loss of hardening
due to missing include files or unlucky header inclusion ordering.

In i386 and x86_64, we can avoid a <tls.h> dependency in the C
code by using the computed constant from <tcb-offsets.h>.  <sysdep.h>
no longer includes these definitions, so there is no cyclic dependency
anymore when computing the <tcb-offsets.h> constants.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
2022-10-18 17:03:55 +02:00

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/* Copyright (C) 1996-2022 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
<https://www.gnu.org/licenses/>. */
#include <sysdeps/unix/sysv/linux/sysdep.h>
#include <tls.h>
/* Defines RTLD_PRIVATE_ERRNO. */
#include <dl-sysdep.h>
/* For Linux we can use the system call table in the header file
/usr/include/asm/unistd.h
of the kernel. But these symbols do not follow the SYS_* syntax
so we have to redefine the `SYS_ify' macro here. */
#undef SYS_ify
#define SYS_ify(syscall_name) __NR_##syscall_name
#ifdef __ASSEMBLER__
/* Linux uses a negative return value to indicate syscall errors, unlike
most Unices, which use the condition codes' carry flag.
Since version 2.1 the return value of a system call might be negative
even if the call succeeded. E.g., the `lseek' system call might return
a large offset. Therefore we must not anymore test for < 0, but test
for a real error by making sure the value in %d0 is a real error
number. Linus said he will make sure the no syscall returns a value
in -1 .. -4095 as a valid result so we can savely test with -4095. */
/* We don't want the label for the error handler to be visible in the symbol
table when we define it here. */
#undef SYSCALL_ERROR_LABEL
#ifdef PIC
#define SYSCALL_ERROR_LABEL .Lsyscall_error
#else
#define SYSCALL_ERROR_LABEL __syscall_error
#endif
#undef PSEUDO
#define PSEUDO(name, syscall_name, args) \
.text; \
ENTRY (name) \
DO_CALL (syscall_name, args); \
cmp.l &-4095, %d0; \
jcc SYSCALL_ERROR_LABEL
#undef PSEUDO_END
#define PSEUDO_END(name) \
SYSCALL_ERROR_HANDLER; \
END (name)
#undef PSEUDO_NOERRNO
#define PSEUDO_NOERRNO(name, syscall_name, args) \
.text; \
ENTRY (name) \
DO_CALL (syscall_name, args)
#undef PSEUDO_END_NOERRNO
#define PSEUDO_END_NOERRNO(name) \
END (name)
#define ret_NOERRNO rts
/* The function has to return the error code. */
#undef PSEUDO_ERRVAL
#define PSEUDO_ERRVAL(name, syscall_name, args) \
.text; \
ENTRY (name) \
DO_CALL (syscall_name, args); \
negl %d0
#undef PSEUDO_END_ERRVAL
#define PSEUDO_END_ERRVAL(name) \
END (name)
#define ret_ERRVAL rts
#ifdef PIC
# if RTLD_PRIVATE_ERRNO
# define SYSCALL_ERROR_HANDLER \
SYSCALL_ERROR_LABEL: \
PCREL_OP (lea, rtld_errno, %a0, %a0); \
neg.l %d0; \
move.l %d0, (%a0); \
move.l &-1, %d0; \
/* Copy return value to %a0 for syscalls that are declared to return \
a pointer (e.g., mmap). */ \
move.l %d0, %a0; \
rts;
# elif defined _LIBC_REENTRANT
# if IS_IN (libc)
# define SYSCALL_ERROR_ERRNO __libc_errno
# else
# define SYSCALL_ERROR_ERRNO errno
# endif
# define SYSCALL_ERROR_HANDLER \
SYSCALL_ERROR_LABEL: \
neg.l %d0; \
move.l %d0, -(%sp); \
cfi_adjust_cfa_offset (4); \
jbsr __m68k_read_tp@PLTPC; \
SYSCALL_ERROR_LOAD_GOT (%a1); \
add.l (SYSCALL_ERROR_ERRNO@TLSIE, %a1), %a0; \
move.l (%sp)+, (%a0); \
cfi_adjust_cfa_offset (-4); \
move.l &-1, %d0; \
/* Copy return value to %a0 for syscalls that are declared to return \
a pointer (e.g., mmap). */ \
move.l %d0, %a0; \
rts;
# else /* !_LIBC_REENTRANT */
/* Store (- %d0) into errno through the GOT. */
# define SYSCALL_ERROR_HANDLER \
SYSCALL_ERROR_LABEL: \
move.l (errno@GOTPC, %pc), %a0; \
neg.l %d0; \
move.l %d0, (%a0); \
move.l &-1, %d0; \
/* Copy return value to %a0 for syscalls that are declared to return \
a pointer (e.g., mmap). */ \
move.l %d0, %a0; \
rts;
# endif /* _LIBC_REENTRANT */
#else
# define SYSCALL_ERROR_HANDLER /* Nothing here; code in sysdep.S is used. */
#endif /* PIC */
/* Linux takes system call arguments in registers:
syscall number %d0 call-clobbered
arg 1 %d1 call-clobbered
arg 2 %d2 call-saved
arg 3 %d3 call-saved
arg 4 %d4 call-saved
arg 5 %d5 call-saved
arg 6 %a0 call-clobbered
The stack layout upon entering the function is:
24(%sp) Arg# 6
20(%sp) Arg# 5
16(%sp) Arg# 4
12(%sp) Arg# 3
8(%sp) Arg# 2
4(%sp) Arg# 1
(%sp) Return address
(Of course a function with say 3 arguments does not have entries for
arguments 4 and 5.)
Separate move's are faster than movem, but need more space. Since
speed is more important, we don't use movem. Since %a0 and %a1 are
scratch registers, we can use them for saving as well. */
#define DO_CALL(syscall_name, args) \
move.l &SYS_ify(syscall_name), %d0; \
DOARGS_##args \
trap &0; \
UNDOARGS_##args
#define DOARGS_0 /* No arguments to frob. */
#define UNDOARGS_0 /* No arguments to unfrob. */
#define _DOARGS_0(n) /* No arguments to frob. */
#define DOARGS_1 _DOARGS_1 (4)
#define _DOARGS_1(n) move.l n(%sp), %d1; _DOARGS_0 (n)
#define UNDOARGS_1 UNDOARGS_0
#define DOARGS_2 _DOARGS_2 (8)
#define _DOARGS_2(n) move.l %d2, %a0; cfi_register (%d2, %a0); \
move.l n(%sp), %d2; _DOARGS_1 (n-4)
#define UNDOARGS_2 UNDOARGS_1; move.l %a0, %d2; cfi_restore (%d2)
#define DOARGS_3 _DOARGS_3 (12)
#define _DOARGS_3(n) move.l %d3, %a1; cfi_register (%d3, %a1); \
move.l n(%sp), %d3; _DOARGS_2 (n-4)
#define UNDOARGS_3 UNDOARGS_2; move.l %a1, %d3; cfi_restore (%d3)
#define DOARGS_4 _DOARGS_4 (16)
#define _DOARGS_4(n) move.l %d4, -(%sp); \
cfi_adjust_cfa_offset (4); cfi_rel_offset (%d4, 0); \
move.l n+4(%sp), %d4; _DOARGS_3 (n)
#define UNDOARGS_4 UNDOARGS_3; move.l (%sp)+, %d4; \
cfi_adjust_cfa_offset (-4); cfi_restore (%d4)
#define DOARGS_5 _DOARGS_5 (20)
#define _DOARGS_5(n) move.l %d5, -(%sp); \
cfi_adjust_cfa_offset (4); cfi_rel_offset (%d5, 0); \
move.l n+4(%sp), %d5; _DOARGS_4 (n)
#define UNDOARGS_5 UNDOARGS_4; move.l (%sp)+, %d5; \
cfi_adjust_cfa_offset (-4); cfi_restore (%d5)
#define DOARGS_6 _DOARGS_6 (24)
#define _DOARGS_6(n) _DOARGS_5 (n-4); move.l %a0, -(%sp); \
cfi_adjust_cfa_offset (4); \
move.l n+12(%sp), %a0;
#define UNDOARGS_6 move.l (%sp)+, %a0; cfi_adjust_cfa_offset (-4); \
UNDOARGS_5
#define ret rts
#if 0 /* Not used by Linux */
#define r0 %d0
#define r1 %d1
#define MOVE(x,y) movel x , y
#endif
#else /* not __ASSEMBLER__ */
/* Define a macro which expands inline into the wrapper code for a system
call. This use is for internal calls that do not need to handle errors
normally. It will never touch errno. This returns just what the kernel
gave back. */
#undef INTERNAL_SYSCALL
#define INTERNAL_SYSCALL_NCS(name, nr, args...) \
({ unsigned int _sys_result; \
{ \
/* Load argument values in temporary variables
to perform side effects like function calls
before the call used registers are set. */ \
LOAD_ARGS_##nr (args) \
LOAD_REGS_##nr \
register int _d0 asm ("%d0") = name; \
asm volatile ("trap #0" \
: "=d" (_d0) \
: "0" (_d0) ASM_ARGS_##nr \
: "memory"); \
_sys_result = _d0; \
} \
(int) _sys_result; })
#define INTERNAL_SYSCALL(name, nr, args...) \
INTERNAL_SYSCALL_NCS (__NR_##name, nr, ##args)
#define LOAD_ARGS_0()
#define LOAD_REGS_0
#define ASM_ARGS_0
#define LOAD_ARGS_1(a1) \
LOAD_ARGS_0 () \
int __arg1 = (int) (a1);
#define LOAD_REGS_1 \
register int _d1 asm ("d1") = __arg1; \
LOAD_REGS_0
#define ASM_ARGS_1 ASM_ARGS_0, "d" (_d1)
#define LOAD_ARGS_2(a1, a2) \
LOAD_ARGS_1 (a1) \
int __arg2 = (int) (a2);
#define LOAD_REGS_2 \
register int _d2 asm ("d2") = __arg2; \
LOAD_REGS_1
#define ASM_ARGS_2 ASM_ARGS_1, "d" (_d2)
#define LOAD_ARGS_3(a1, a2, a3) \
LOAD_ARGS_2 (a1, a2) \
int __arg3 = (int) (a3);
#define LOAD_REGS_3 \
register int _d3 asm ("d3") = __arg3; \
LOAD_REGS_2
#define ASM_ARGS_3 ASM_ARGS_2, "d" (_d3)
#define LOAD_ARGS_4(a1, a2, a3, a4) \
LOAD_ARGS_3 (a1, a2, a3) \
int __arg4 = (int) (a4);
#define LOAD_REGS_4 \
register int _d4 asm ("d4") = __arg4; \
LOAD_REGS_3
#define ASM_ARGS_4 ASM_ARGS_3, "d" (_d4)
#define LOAD_ARGS_5(a1, a2, a3, a4, a5) \
LOAD_ARGS_4 (a1, a2, a3, a4) \
int __arg5 = (int) (a5);
#define LOAD_REGS_5 \
register int _d5 asm ("d5") = __arg5; \
LOAD_REGS_4
#define ASM_ARGS_5 ASM_ARGS_4, "d" (_d5)
#define LOAD_ARGS_6(a1, a2, a3, a4, a5, a6) \
LOAD_ARGS_5 (a1, a2, a3, a4, a5) \
int __arg6 = (int) (a6);
#define LOAD_REGS_6 \
register int _a0 asm ("a0") = __arg6; \
LOAD_REGS_5
#define ASM_ARGS_6 ASM_ARGS_5, "a" (_a0)
#undef HAVE_INTERNAL_BRK_ADDR_SYMBOL
#define HAVE_INTERNAL_BRK_ADDR_SYMBOL 1
#endif /* not __ASSEMBLER__ */
/* M68K needs system-supplied DSO to access TLS helpers
even when statically linked. */
#define NEED_STATIC_SYSINFO_DSO 1
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