From 05ac953c23f90b2328d393f7eecde96e41aed067 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Wed, 20 Feb 2019 19:49:12 -0800 Subject: [PATCH] dmi: check both the AC and ID flags at the same time 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 --- com32/include/x86/cpu.h | 17 +++++++++++------ core/dmi.c | 6 ++++-- 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 #include -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; -- 2.11.4.GIT