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eal/x86: use cpuid builtin

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GCC does have the __get_cpuid_count builtin which checks for maximum
supported leaf, but implementations differ between CLANG and GCC.

This change provides an implementation compatible with both GCC and
CLANG 3.4+.

Signed-off-by: Sergio Gonzalez Monroy <sergio.gonzalez.monroy@intel.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>
This commit is contained in:
Sergio Gonzalez Monroy 2017-08-23 16:00:27 +01:00 committed by Thomas Monjalon
parent d65b3b1668
commit 5b618b5b29
1 changed files with 8 additions and 32 deletions
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40
lib/librte_eal/common/arch/x86/rte_cpuflags.c
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@ -36,6 +36,7 @@
#include <stdio.h>
#include <errno.h>
#include <stdint.h>
#include <cpuid.h>
enum cpu_register_t {
RTE_REG_EAX = 0,
@ -156,38 +157,12 @@ const struct feature_entry rte_cpu_feature_table[] = {
FEAT_DEF(INVTSC, 0x80000007, 0, RTE_REG_EDX, 8)
};
/*
* Execute CPUID instruction and get contents of a specific register
*
* This function, when compiled with GCC, will generate architecture-neutral
* code, as per GCC manual.
*/
static void
rte_cpu_get_features(uint32_t leaf, uint32_t subleaf, cpuid_registers_t out)
{
#if defined(__i386__) && defined(__PIC__)
/* %ebx is a forbidden register if we compile with -fPIC or -fPIE */
asm volatile("movl %%ebx,%0 ; cpuid ; xchgl %%ebx,%0"
: "=r" (out[RTE_REG_EBX]),
"=a" (out[RTE_REG_EAX]),
"=c" (out[RTE_REG_ECX]),
"=d" (out[RTE_REG_EDX])
: "a" (leaf), "c" (subleaf));
#else
asm volatile("cpuid"
: "=a" (out[RTE_REG_EAX]),
"=b" (out[RTE_REG_EBX]),
"=c" (out[RTE_REG_ECX]),
"=d" (out[RTE_REG_EDX])
: "a" (leaf), "c" (subleaf));
#endif
}
int
rte_cpu_get_flag_enabled(enum rte_cpu_flag_t feature)
{
const struct feature_entry *feat;
cpuid_registers_t regs;
unsigned int maxleaf;
if (feature >= RTE_CPUFLAG_NUMFLAGS)
/* Flag does not match anything in the feature tables */
@ -199,13 +174,14 @@ rte_cpu_get_flag_enabled(enum rte_cpu_flag_t feature)
/* This entry in the table wasn't filled out! */
return -EFAULT;
rte_cpu_get_features(feat->leaf & 0xffff0000, 0, regs);
if (((regs[RTE_REG_EAX] ^ feat->leaf) & 0xffff0000) ||
regs[RTE_REG_EAX] < feat->leaf)
maxleaf = __get_cpuid_max(feat->leaf & 0x80000000, NULL);
if (maxleaf < feat->leaf)
return 0;
/* get the cpuid leaf containing the desired feature */
rte_cpu_get_features(feat->leaf, feat->subleaf, regs);
__cpuid_count(feat->leaf, feat->subleaf,
regs[RTE_REG_EAX], regs[RTE_REG_EBX],
regs[RTE_REG_ECX], regs[RTE_REG_EDX]);
/* check if the feature is enabled */
return (regs[feat->reg] >> feat->bit) & 1;