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authorH. Peter Anvin <hpa@zytor.com>2019-02-20 19:49:12 -0800
committerH. Peter Anvin <hpa@zytor.com>2019-02-20 19:49:12 -0800
commit05ac953c23f90b2328d393f7eecde96e41aed067 (patch)
tree759fe3d75276aac5c7f9dd7dcbfb56323a85fff1
parent090ba3a2aa9bc3f6b5491b09f51b76836c014fee (diff)
downloadsyslinux-master.tar.gz
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syslinux-master.zip
dmi: check both the AC and ID flags at the same timeHEADmaster
There is no reason to do the fairly complex flag-test sequence twice, when we might as well check for both flags at the same time. Signed-off-by: H. Peter Anvin <hpa@zytor.com>
-rw-r--r--com32/include/x86/cpu.h17
-rw-r--r--core/dmi.c6
2 files changed, 15 insertions, 8 deletions
diff --git a/com32/include/x86/cpu.h b/com32/include/x86/cpu.h
index 4bbcc802..f61e4389 100644
--- a/com32/include/x86/cpu.h
+++ b/com32/include/x86/cpu.h
@@ -6,13 +6,13 @@
#include <stdbool.h>
#include <x86/regs.h>
-static inline __constfunc bool cpu_has_eflag(unsigned long flag)
+static inline __constfunc unsigned long cpu_has_eflags(unsigned long flags)
{
unsigned long f1, f2;
- if (__builtin_constant_p(flag)) {
- if (!(flag & ~(unsigned long)KNOWN_EFLAGS))
- return true;
+ if (__builtin_constant_p(flags)) {
+ if (!(flags & ~(unsigned long)KNOWN_EFLAGS))
+ return flags; /* We know we have them all */
}
asm("pushf ; "
@@ -25,9 +25,14 @@ static inline __constfunc bool cpu_has_eflag(unsigned long flag)
"pushf ; "
"pop %1 ; "
"popf"
- : "=&r" (f1), "=&r" (f2) : "ri" (flag));
+ : "=&r" (f1), "=&r" (f2) : "ri" (flags));
+
+ return (f1 ^ f2) & flags;
+}
- return !!((f1 ^ f2) & flag);
+static inline __constfunc bool cpu_has_eflag(unsigned long flag)
+{
+ return cpu_has_eflags(flag) != 0;
}
static inline uint64_t rdtsc(void)
diff --git a/core/dmi.c b/core/dmi.c
index 550b63e2..9a108341 100644
--- a/core/dmi.c
+++ b/core/dmi.c
@@ -317,6 +317,7 @@ struct cpuflag {
static void sysappend_set_cpu(void)
{
+ unsigned long have_eflags;
static char cpu_str[6+6] = "CPU=";
char *p = cpu_str + 4;
static const struct cpuflag cpuflags[] = {
@@ -331,10 +332,11 @@ static void sysappend_set_cpu(void)
const struct cpuflag *cf;
/* Not technically from DMI, but it fit here... */
+ have_eflags = cpu_has_eflags(EFLAGS_ID|EFLAGS_AC);
- if (!cpu_has_eflag(EFLAGS_ID)) {
+ if (!(have_eflags & EFLAGS_ID)) {
/* No CPUID */
- *p++ = cpu_has_eflag(EFLAGS_AC) ? '4' : '3';
+ *p++ = (have_eflags & EFLAGS_AC) ? '4' : '3';
} else {
uint32_t flags[4], eax, ebx, family;
uint32_t ext_level;