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Use x86 highest basic before calling a leaf function 

This was a latent bug that just surfaced on a Sun Core2 workstation. RDSEED caused an illegal instruction exception on the Core2. It seems we managed to miss it because old processors had family and stepping values so low they never set CPUID.EBX.RDSEED[bit 18] = 1. Newer processors had the feature so CPUID.EBX.RDSEED[bit 18] = 1 was accurate.
pull/566/head
Jeffrey Walton 2018-01-11 17:59:24 -05:00
parent 591d70f1c7
commit 788cd1794d
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GPG Key ID: B36AB348921B1838
2 changed files with 3 additions and 3 deletions
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4
cpu.cpp
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@ -240,7 +240,7 @@ void DetectX86Features()
g_cacheLineSize = 8 * GETBYTE(cpuid1[1], 1); g_cacheLineSize = 8 * GETBYTE(cpuid1[1], 1);
g_hasRDRAND = !!(cpuid1[2] /*ECX*/ & RDRAND_FLAG); g_hasRDRAND = !!(cpuid1[2] /*ECX*/ & RDRAND_FLAG);
if (cpuid1[0] /*EAX*/ >= 7) if (cpuid0[0] /*EAX*/ >= 7)
{ {
if (CpuId(7, 0, cpuid2)) if (CpuId(7, 0, cpuid2))
{ {
@ -261,7 +261,7 @@ void DetectX86Features()
g_cacheLineSize = GETBYTE(cpuid2[2], 0); g_cacheLineSize = GETBYTE(cpuid2[2], 0);
g_hasRDRAND = !!(cpuid1[2] /*ECX*/ & RDRAND_FLAG); g_hasRDRAND = !!(cpuid1[2] /*ECX*/ & RDRAND_FLAG);
if (cpuid1[0] /*EAX*/ >= 7) if (cpuid0[0] /*EAX*/ >= 7)
{ {
if (CpuId(7, 0, cpuid2)) if (CpuId(7, 0, cpuid2))
{ {