| |
| /*--------------------------------------------------------------------*/ |
| /*--- Doing syscalls. m_syscall.c ---*/ |
| /*--------------------------------------------------------------------*/ |
| |
| /* |
| This file is part of Valgrind, a dynamic binary instrumentation |
| framework. |
| |
| Copyright (C) 2000-2005 Julian Seward |
| jseward@acm.org |
| |
| This program is free software; you can redistribute it and/or |
| modify it under the terms of the GNU General Public License as |
| published by the Free Software Foundation; either version 2 of the |
| License, or (at your option) any later version. |
| |
| This program 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 |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program; if not, write to the Free Software |
| Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 02111-1307, USA. |
| |
| The GNU General Public License is contained in the file COPYING. |
| */ |
| |
| #include "core.h" |
| #include "pub_core_syscall.h" |
| |
| /* --------------------------------------------------------------------- |
| Building syscall return values. |
| ------------------------------------------------------------------ */ |
| |
| /* Make a SysRes value from an syscall return value. This is |
| Linux-specific. |
| |
| From: |
| http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/unix/sysv/ |
| linux/i386/sysdep.h? |
| rev=1.28&content-type=text/x-cvsweb-markup&cvsroot=glibc |
| |
| 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 |
| safely test with -4095. |
| */ |
| SysRes VG_(mk_SysRes) ( UWord val ) { |
| SysRes res; |
| #if defined(VGP_x86_linux) |
| res.isError = val >= -4095 && val <= -1; |
| res.val = res.isError ? -val : val; |
| #elif defined(VGP_amd64_linux) |
| res.isError = val >= -4095 && val <= -1; |
| res.val = res.isError ? -val : val; |
| #else |
| # error Unknown platform |
| #endif |
| return res; |
| } |
| |
| SysRes VG_(mk_SysRes_Error) ( UWord val ) { |
| SysRes r = { val, True }; |
| return r; |
| } |
| |
| SysRes VG_(mk_SysRes_Success) ( UWord val ) { |
| SysRes r = { val, False }; |
| return r; |
| } |
| |
| |
| /* --------------------------------------------------------------------- |
| A function for doing syscalls. |
| ------------------------------------------------------------------ */ |
| |
| extern UInt do_syscall_WRK ( |
| UInt syscall_no, |
| UInt a1, UInt a2, UInt a3, |
| UInt a4, UInt a5, UInt a6 |
| ); |
| #if defined(VGP_x86_linux) |
| /* Incoming args (syscall number + up to 6 args) come on the stack. |
| (ie. the C calling convention). |
| |
| The syscall number goes in %eax. The args are passed to the syscall in |
| the regs %ebx, %ecx, %edx, %esi, %edi, %ebp, ie. the kernel's syscall |
| calling convention. |
| |
| %eax gets the return value. Not sure which registers the kernel |
| clobbers, so we preserve all the callee-save regs (%esi, %edi, %ebx, |
| %ebp). |
| */ |
| asm( |
| "do_syscall_WRK:\n" |
| " push %esi\n" |
| " push %edi\n" |
| " push %ebx\n" |
| " push %ebp\n" |
| " movl 16+ 4(%esp),%eax\n" |
| " movl 16+ 8(%esp),%ebx\n" |
| " movl 16+12(%esp),%ecx\n" |
| " movl 16+16(%esp),%edx\n" |
| " movl 16+20(%esp),%esi\n" |
| " movl 16+24(%esp),%edi\n" |
| " movl 16+28(%esp),%ebp\n" |
| " int $0x80\n" |
| " popl %ebp\n" |
| " popl %ebx\n" |
| " popl %edi\n" |
| " popl %esi\n" |
| " ret\n" |
| ); |
| #elif defined(VGP_amd64_linux) |
| /* Incoming args (syscall number + up to 6 args) come in %rdi, %rsi, |
| %rdx, %rcx, %r8, %r9, and the last one on the stack (ie. the C |
| calling convention). |
| |
| The syscall number goes in %rax. The args are passed to the syscall in |
| the regs %rdi, %rsi, %rdx, %r10, %r8, %r9 (yes, really %r10, not %rcx), |
| ie. the kernel's syscall calling convention. |
| |
| %rax gets the return value. %rcx and %r11 are clobbered by the syscall; |
| no matter, they are caller-save (the syscall clobbers no callee-save |
| regs, so we don't have to do any register saving/restoring). |
| */ |
| asm( |
| "do_syscall_WRK:\n" |
| /* Convert function calling convention --> syscall calling |
| convention */ |
| " movq %rdi, %rax\n" |
| " movq %rsi, %rdi\n" |
| " movq %rdx, %rsi\n" |
| " movq %rcx, %rdx\n" |
| " movq %r8, %r10\n" |
| " movq %r9, %r8\n" |
| " movq 8(%rsp), %r9\n" /* last arg from stack */ |
| " syscall\n" |
| " ret\n" |
| ); |
| #else |
| # error Unknown platform |
| #endif |
| |
| SysRes VG_(do_syscall) ( UWord sysno, UWord a1, UWord a2, UWord a3, |
| UWord a4, UWord a5, UWord a6 ) |
| { |
| UWord val = do_syscall_WRK(sysno,a1,a2,a3,a4,a5,a6); |
| return VG_(mk_SysRes)( val ); |
| } |
| |
| /*--------------------------------------------------------------------*/ |
| /*--- end ---*/ |
| /*--------------------------------------------------------------------*/ |