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Possible fix for bug #77357

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Don't invoke CPUID with feature levels above the supported maximum.
In this case CPUID will return the highest supported basic information
leaf, which will have unrelated bits in the relevant positions.
This commit is contained in:
Nikita Popov 2019-01-03 10:24:48 +01:00
parent 349dbb7938
commit 5a361c3a54
1 changed files with 11 additions and 3 deletions
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14
Zend/zend_cpuinfo.c
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@ -77,16 +77,24 @@ void zend_cpu_startup(void)
{
if (!cpuinfo.initialized) {
zend_cpu_info ebx;
int max_feature;
cpuinfo.initialized = 1;
__zend_cpuid(0, 0, &cpuinfo);
if (cpuinfo.eax == 0) {
max_feature = cpuinfo.eax;
if (max_feature == 0) {
return;
}
__zend_cpuid(1, 0, &cpuinfo);
/* for avx2 */
__zend_cpuid(7, 0, &ebx);
cpuinfo.ebx = ebx.ebx;
if (max_feature >= 7) {
__zend_cpuid(7, 0, &ebx);
cpuinfo.ebx = ebx.ebx;
} else {
cpuinfo.ebx = 0;
}
}
}