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Provide userspace versions of do_cpuid() and cpuid_count() on i386.

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Some older compilers, when generating PIC code, cannot handle inline
asm that clobbers %ebx (because %ebx is used as the GOT offset
register).  Userspace versions avoid clobbering %ebx by saving it to
stack before executing the CPUID instruction.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
This commit is contained in:
Konstantin Belousov 2019-02-14 13:53:11 +00:00
parent 5864456d1a
commit 642bb66b63
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=344118
1 changed files with 30 additions and 4 deletions
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34
sys/i386/include/cpufunc.h
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@ -108,21 +108,47 @@ disable_intr(void)
__asm __volatile("cli" : : : "memory");
}
#ifdef _KERNEL
static __inline void
do_cpuid(u_int ax, u_int *p)
{
__asm __volatile("cpuid"
: "=a" (p[0]), "=b" (p[1]), "=c" (p[2]), "=d" (p[3])
: "0" (ax));
: "=a" (p[0]), "=b" (p[1]), "=c" (p[2]), "=d" (p[3])
: "0" (ax));
}
static __inline void
cpuid_count(u_int ax, u_int cx, u_int *p)
{
__asm __volatile("cpuid"
: "=a" (p[0]), "=b" (p[1]), "=c" (p[2]), "=d" (p[3])
: "0" (ax), "c" (cx));
: "=a" (p[0]), "=b" (p[1]), "=c" (p[2]), "=d" (p[3])
: "0" (ax), "c" (cx));
}
#else
static __inline void
do_cpuid(u_int ax, u_int *p)
{
__asm __volatile(
"pushl\t%%ebx\n\t"
"cpuid\n\t"
"movl\t%%ebx,%1\n\t"
"popl\t%%ebx"
: "=a" (p[0]), "=DS" (p[1]), "=c" (p[2]), "=d" (p[3])
: "0" (ax));
}
static __inline void
cpuid_count(u_int ax, u_int cx, u_int *p)
{
__asm __volatile(
"pushl\t%%ebx\n\t"
"cpuid\n\t"
"movl\t%%ebx,%1\n\t"
"popl\t%%ebx"
: "=a" (p[0]), "=DS" (p[1]), "=c" (p[2]), "=d" (p[3])
: "0" (ax), "c" (cx));
}
#endif
static __inline void
enable_intr(void)