From: Ewan <[email protected]> The __get_cpuid() and __get_cpuid_count() functions use "__leaf & 0x80000000" to determine the CPUID range base, which only distinguishes between Basic (0x0) and Extended (0x80000000) ranges. This causes queries to the Centaur/Zhaoxin range (0xC0000000) to be incorrectly mapped to the Extended range, and always return 0 (failure) on Centaur/Zhaoxin processors that support CPUID 0xC000xxxx leaves (e.g. PadLock feature detection via leaf 0xC0000001).
Replace the bitmask with explicit range checks that correctly identify all four CPUID ranges: Basic (0x0), Hypervisor (0x40000000), Extended (0x80000000), and Centaur/Zhaoxin (0xC0000000). Additionally, the Hypervisor range (0x40000000) is also handled as an extra improvement, since the original bitmask incorrectly mapped it to the Basic range (0x0). Also update the __get_cpuid_max() comment to document the newly supported range base values. Signed-off-by: Ewanhaioc <[email protected]> --- gcc/config/i386/cpuid.h | 29 +++++++++++++++++++++++++---- 1 file changed, 25 insertions(+), 4 deletions(-) diff --git a/gcc/config/i386/cpuid.h b/gcc/config/i386/cpuid.h index f493360b1e8..083e4f62498 100644 --- a/gcc/config/i386/cpuid.h +++ b/gcc/config/i386/cpuid.h @@ -264,8 +264,9 @@ /* Return highest supported input value for cpuid instruction. ext can - be either 0x0 or 0x80000000 to return highest supported value for - basic or extended cpuid information. Function returns 0 if cpuid + be either 0x0, 0x40000000, 0x80000000, or 0xC0000000 to return + highest supported value for basic, hypervisor, extended, or + Centaur/Zhaoxin cpuid information. Function returns 0 if cpuid is not supported or whatever cpuid returns in eax register. If sig pointer is non-null, then first four bytes of the signature (as found in ebx register) are returned in location pointed by sig. */ @@ -330,7 +331,17 @@ __get_cpuid (unsigned int __leaf, unsigned int *__eax, unsigned int *__ebx, unsigned int *__ecx, unsigned int *__edx) { - unsigned int __ext = __leaf & 0x80000000; + unsigned int __ext; + + if (__leaf >= 0xC0000000) + __ext = 0xC0000000; + else if (__leaf >= 0x80000000) + __ext = 0x80000000; + else if (__leaf >= 0x40000000) + __ext = 0x40000000; + else + __ext = 0x00000000; + unsigned int __maxlevel = __get_cpuid_max (__ext, 0); if (__maxlevel == 0 || __maxlevel < __leaf) @@ -347,7 +358,17 @@ __get_cpuid_count (unsigned int __leaf, unsigned int __subleaf, unsigned int *__eax, unsigned int *__ebx, unsigned int *__ecx, unsigned int *__edx) { - unsigned int __ext = __leaf & 0x80000000; + unsigned int __ext; + + if (__leaf >= 0xC0000000) + __ext = 0xC0000000; + else if (__leaf >= 0x80000000) + __ext = 0x80000000; + else if (__leaf >= 0x40000000) + __ext = 0x40000000; + else + __ext = 0x00000000; + unsigned int __maxlevel = __get_cpuid_max (__ext, 0); if (__builtin_expect (__maxlevel == 0, 0) || __maxlevel < __leaf) -- 2.34.1
