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- /* Copyright (C) 2001-2005, 2007 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/>. */
- #ifndef _LINUX_X86_64_SYSDEP_H
- #define _LINUX_X86_64_SYSDEP_H 1
- /* There is some commonality. */
- #include <sys/syscall.h>
- #include <common/sysdep.h>
- #ifdef __ASSEMBLER__
- /* Syntactic details of assembler. */
- /* ELF uses byte-counts for .align, most others use log2 of count of bytes. */
- #define ALIGNARG(log2) 1<<log2
- /* For ELF we need the `.type' directive to make shared libs work right. */
- #define ASM_TYPE_DIRECTIVE(name,typearg) .type name,typearg;
- #define ASM_SIZE_DIRECTIVE(name) .size name,.-name;
- /* In ELF C symbols are asm symbols. */
- #undef NO_UNDERSCORES
- #define NO_UNDERSCORES
- /* Define an entry point visible from C. */
- #define ENTRY(name) \
- ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME(name); \
- ASM_TYPE_DIRECTIVE (C_SYMBOL_NAME(name),@function) \
- .align ALIGNARG(4); \
- C_LABEL(name) \
- cfi_startproc; \
- CALL_MCOUNT
- #undef END
- #define END(name) \
- cfi_endproc; \
- ASM_SIZE_DIRECTIVE(name)
- /* If compiled for profiling, call `mcount' at the start of each function. */
- #ifdef PROF
- /* The mcount code relies on a normal frame pointer being on the stack
- to locate our caller, so push one just for its benefit. */
- #define CALL_MCOUNT \
- pushq %rbp; \
- cfi_adjust_cfa_offset(8); \
- movq %rsp, %rbp; \
- cfi_def_cfa_register(%rbp); \
- call JUMPTARGET(mcount); \
- popq %rbp; \
- cfi_def_cfa(rsp,8);
- #else
- #define CALL_MCOUNT /* Do nothing. */
- #endif
- #ifdef NO_UNDERSCORES
- /* Since C identifiers are not normally prefixed with an underscore
- on this system, the asm identifier `syscall_error' intrudes on the
- C name space. Make sure we use an innocuous name. */
- #define syscall_error __syscall_error
- #define mcount _mcount
- #endif
- #define PSEUDO(name, syscall_name, args) \
- lose: \
- jmp JUMPTARGET(syscall_error) \
- .globl syscall_error; \
- ENTRY (name) \
- DO_CALL (syscall_name, args); \
- jb lose
- #undef PSEUDO_END
- #define PSEUDO_END(name) \
- END (name)
- #undef JUMPTARGET
- #ifdef __PIC__
- #define JUMPTARGET(name) name##@PLT
- #else
- #define JUMPTARGET(name) name
- #endif
- /* Local label name for asm code. */
- #ifndef L
- #define L(name) .L##name
- #endif
- #endif /* __ASSEMBLER__ */
- /* 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
- /* This is a kludge to make syscalls.list find these under the names
- pread and pwrite, since some kernel headers define those names
- and some define the *64 names for the same system calls. */
- #if !defined __NR_pread && defined __NR_pread64
- # define __NR_pread __NR_pread64
- #endif
- #if !defined __NR_pwrite && defined __NR_pwrite64
- # define __NR_pwrite __NR_pwrite64
- #endif
- /* This is to help the old kernel headers where __NR_semtimedop is not
- available. */
- #ifndef __NR_semtimedop
- # define __NR_semtimedop 220
- #endif
- #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 %eax
- 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 handle to be global when we define
- it here. */
- # ifdef __PIC__
- # define SYSCALL_ERROR_LABEL 0f
- # else
- # define SYSCALL_ERROR_LABEL syscall_error
- # endif
- # undef PSEUDO
- # define PSEUDO(name, syscall_name, args) \
- .text; \
- ENTRY (name) \
- DO_CALL (syscall_name, args); \
- cmpq $-4095, %rax; \
- jae SYSCALL_ERROR_LABEL; \
- L(pseudo_end):
- # 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 ret
- # undef PSEUDO_ERRVAL
- # define PSEUDO_ERRVAL(name, syscall_name, args) \
- .text; \
- ENTRY (name) \
- DO_CALL (syscall_name, args); \
- negq %rax
- # undef PSEUDO_END_ERRVAL
- # define PSEUDO_END_ERRVAL(name) \
- END (name)
- # define ret_ERRVAL ret
- # ifndef __PIC__
- # define SYSCALL_ERROR_HANDLER /* Nothing here; code in sysdep.S is used. */
- # elif defined(RTLD_PRIVATE_ERRNO)
- # define SYSCALL_ERROR_HANDLER \
- 0: \
- leaq rtld_errno(%rip), %rcx; \
- xorl %edx, %edx; \
- subq %rax, %rdx; \
- movl %edx, (%rcx); \
- orq $-1, %rax; \
- jmp L(pseudo_end);
- # elif USE___THREAD
- # ifndef NOT_IN_libc
- # define SYSCALL_ERROR_ERRNO __libc_errno
- # else
- # define SYSCALL_ERROR_ERRNO errno
- # endif
- # define SYSCALL_ERROR_HANDLER \
- 0: \
- movq SYSCALL_ERROR_ERRNO@GOTTPOFF(%rip), %rcx;\
- xorl %edx, %edx; \
- subq %rax, %rdx; \
- movl %edx, %fs:(%rcx); \
- orq $-1, %rax; \
- jmp L(pseudo_end);
- # elif defined _LIBC_REENTRANT
- /* Store (- %rax) into errno through the GOT.
- Note that errno occupies only 4 bytes. */
- # define SYSCALL_ERROR_HANDLER \
- 0: \
- xorl %edx, %edx; \
- subq %rax, %rdx; \
- pushq %rdx; \
- cfi_adjust_cfa_offset(8); \
- call __errno_location@PLT; \
- popq %rdx; \
- cfi_adjust_cfa_offset(-8); \
- movl %edx, (%rax); \
- orq $-1, %rax; \
- jmp L(pseudo_end);
- /* A quick note: it is assumed that the call to `__errno_location' does
- not modify the stack! */
- # else /* Not _LIBC_REENTRANT. */
- # define SYSCALL_ERROR_HANDLER \
- 0:movq errno@GOTPCREL(%RIP), %rcx; \
- xorl %edx, %edx; \
- subq %rax, %rdx; \
- movl %edx, (%rcx); \
- orq $-1, %rax; \
- jmp L(pseudo_end);
- # endif /* __PIC__ */
- /* The Linux/x86-64 kernel expects the system call parameters in
- registers according to the following table:
- syscall number rax
- arg 1 rdi
- arg 2 rsi
- arg 3 rdx
- arg 4 r10
- arg 5 r8
- arg 6 r9
- The Linux kernel uses and destroys internally these registers:
- return address from
- syscall rcx
- eflags from syscall r11
- Normal function call, including calls to the system call stub
- functions in the libc, get the first six parameters passed in
- registers and the seventh parameter and later on the stack. The
- register use is as follows:
- system call number in the DO_CALL macro
- arg 1 rdi
- arg 2 rsi
- arg 3 rdx
- arg 4 rcx
- arg 5 r8
- arg 6 r9
- We have to take care that the stack is aligned to 16 bytes. When
- called the stack is not aligned since the return address has just
- been pushed.
- Syscalls of more than 6 arguments are not supported. */
- # undef DO_CALL
- # define DO_CALL(syscall_name, args) \
- DOARGS_##args \
- movl $SYS_ify (syscall_name), %eax; \
- syscall;
- # define DOARGS_0 /* nothing */
- # define DOARGS_1 /* nothing */
- # define DOARGS_2 /* nothing */
- # define DOARGS_3 /* nothing */
- # define DOARGS_4 movq %rcx, %r10;
- # define DOARGS_5 DOARGS_4
- # define DOARGS_6 DOARGS_5
- #endif /* __ASSEMBLER__ */
- /* Pointer mangling support. */
- #if defined NOT_IN_libc && defined IS_IN_rtld
- /* We cannot use the thread descriptor because in ld.so we use setjmp
- earlier than the descriptor is initialized. */
- # ifdef __ASSEMBLER__
- # define PTR_MANGLE(reg) xorq __pointer_chk_guard_local(%rip), reg; \
- rolq $17, reg
- # define PTR_DEMANGLE(reg) rorq $17, reg; \
- xorq __pointer_chk_guard_local(%rip), reg
- # else
- # define PTR_MANGLE(reg) __asm__ ("xorq __pointer_chk_guard_local(%%rip), %0\n" \
- "rolq $17, %0" \
- : "=r" (reg) : "0" (reg))
- # define PTR_DEMANGLE(reg) __asm__ ("rorq $17, %0\n" \
- "xorq __pointer_chk_guard_local(%%rip), %0" \
- : "=r" (reg) : "0" (reg))
- # endif
- #else
- # ifdef __ASSEMBLER__
- # define PTR_MANGLE(reg) xorq %fs:POINTER_GUARD, reg; \
- rolq $17, reg
- # define PTR_DEMANGLE(reg) rorq $17, reg; \
- xorq %fs:POINTER_GUARD, reg
- # else
- # define PTR_MANGLE(var) __asm__ ("xorq %%fs:%c2, %0\n" \
- "rolq $17, %0" \
- : "=r" (var) \
- : "0" (var), \
- "i" (offsetof (tcbhead_t, \
- pointer_guard)))
- # define PTR_DEMANGLE(var) __asm__ ("rorq $17, %0\n" \
- "xorq %%fs:%c2, %0" \
- : "=r" (var) \
- : "0" (var), \
- "i" (offsetof (tcbhead_t, \
- pointer_guard)))
- # endif
- #endif
- #endif /* linux/x86_64/sysdep.h */
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