diff options
Diffstat (limited to 'plugins/cpuid/cpuid.c')
-rw-r--r-- | plugins/cpuid/cpuid.c | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/plugins/cpuid/cpuid.c b/plugins/cpuid/cpuid.c new file mode 100644 index 0000000..7aaf09c --- /dev/null +++ b/plugins/cpuid/cpuid.c @@ -0,0 +1,61 @@ +/* + * cpuid.c - test for long mode using cpuid instruction + * Copyright (C) 2007 Robert Millan <rmh@aybabtu.com> + * Based on gcc/gcc/config/i386/driver-i386.c + * Copyright (C) 2006, 2007 Free Software Foundation, Inc. + * + * 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 3 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, see <http://www.gnu.org/licenses/>. + */ + +#define cpuid(num,a,b,c,d) \ + asm volatile ("xchgl %%ebx, %1; cpuid; xchgl %%ebx, %1" \ + : "=a" (a), "=r" (b), "=c" (c), "=d" (d) \ + : "0" (num)) + +#define bit_LM (1 << 29) + +int +check_64bit () +{ + unsigned int eax, ebx, ecx, edx; + unsigned int max_level; + unsigned int ext_level; + unsigned char has_longmode = 0; + + /* See if we can use cpuid. */ + asm volatile ("pushfl; pushfl; popl %0; movl %0,%1; xorl %2,%0;" + "pushl %0; popfl; pushfl; popl %0; popfl" + : "=&r" (eax), "=&r" (ebx) + : "i" (0x00200000)); + if (((eax ^ ebx) & 0x00200000) == 0) + goto done; + + /* Check the highest input value for eax. */ + cpuid (0, eax, ebx, ecx, edx); + /* We only look at the first four characters. */ + max_level = eax; + if (max_level == 0) + goto done; + + cpuid (0x80000000, eax, ebx, ecx, edx); + ext_level = eax; + if (ext_level < 0x80000000) + goto done; + + cpuid (0x80000001, eax, ebx, ecx, edx); + has_longmode = !!(edx & bit_LM); + +done: + return has_longmode; +} |