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Add CPUID leaf checks prior to SHA checks

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Some old CPUs do not support CPUID to be called with eax=7
To prevent failures, call CPUID with eax=0 to get the highest possible
eax value (leaf) and compare it to 7.

GCC does this check internally with __get_cpuid_count function

Thanks to Jeffrey Walton for noticing.
This commit is contained in:
Pavel I. Kryukov 2018-03-22 21:57:38 +03:00 committed by Simon Tatham
parent a27f55e819
commit 1ec8a84cf6
1 changed files with 8 additions and 0 deletions
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8
sshsha.c
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@ -501,6 +501,10 @@ const struct ssh_mac ssh_hmac_sha1_96_buggy = {
int supports_sha_ni(void)
{
unsigned int CPUInfo[4];
__cpuid(0, CPUInfo[0], CPUInfo[1], CPUInfo[2], CPUInfo[3]);
if (CPUInfo[0] < 7)
return 0;
__cpuid_count(7, 0, CPUInfo[0], CPUInfo[1], CPUInfo[2], CPUInfo[3]);
return CPUInfo[1] & (1 << 29); /* SHA */
}
@ -510,6 +514,10 @@ int supports_sha_ni(void)
int supports_sha_ni(void)
{
unsigned int CPUInfo[4];
__cpuid(CPUInfo, 0);
if (CPUInfo[0] < 7)
return 0;
__cpuidex(CPUInfo, 7, 0);
return CPUInfo[1] & (1 << 29); /* Check SHA */
}