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Add a clts() wrapper around the 'clts' instruction to <machine/cpufunc.h>

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on x86 and use that to implement stop_emulating() in the fpu/npx code.
Reimplement start_emulating() in the non-XEN case by using load_cr0() and
rcr0() instead of the 'lmsw' and 'smsw' instructions.  Intel explicitly
discourages the use of 'lmsw' and 'smsw' on 80386 and later processors in
the description of these instructions in Volume 2 of the ADM.

Reviewed by:	kib
MFC after:	1 month
This commit is contained in:
jhb 2012-07-09 20:55:39 +00:00
parent fb20c6fee6
commit 501beca671
4 changed files with 31 additions and 17 deletions
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9
sys/amd64/amd64/fpu.c
View File

@ -73,10 +73,6 @@ __FBSDID("$FreeBSD$");
#define fxrstor(addr) __asm __volatile("fxrstor %0" : : "m" (*(addr)))
#define fxsave(addr) __asm __volatile("fxsave %0" : "=m" (*(addr)))
#define ldmxcsr(csr) __asm __volatile("ldmxcsr %0" : : "m" (csr))
#define start_emulating() __asm __volatile( \
"smsw %%ax; orb %0,%%al; lmsw %%ax" \
: : "n" (CR0_TS) : "ax")
#define stop_emulating() __asm __volatile("clts")
static __inline void
xrstor(char *addr, uint64_t mask)
@ -109,13 +105,14 @@ void fnstsw(caddr_t addr);
void fxsave(caddr_t addr);
void fxrstor(caddr_t addr);
void ldmxcsr(u_int csr);
void start_emulating(void);
void stop_emulating(void);
void xrstor(char *addr, uint64_t mask);
void xsave(char *addr, uint64_t mask);
#endif /* __GNUCLIKE_ASM && !lint */
#define start_emulating() load_cr0(rcr0() | CR0_TS)
#define stop_emulating() clts()
#define GET_FPU_CW(thread) ((thread)->td_pcb->pcb_save->sv_env.en_cw)
#define GET_FPU_SW(thread) ((thread)->td_pcb->pcb_save->sv_env.en_sw)

10
sys/amd64/include/cpufunc.h
View File

@ -106,6 +106,13 @@ clflush(u_long addr)
__asm __volatile("clflush %0" : : "m" (*(char *)addr));
}
static __inline void
clts(void)
{
__asm __volatile("clts");
}
static __inline void
disable_intr(void)
{
@ -702,6 +709,9 @@ intr_restore(register_t rflags)
int breakpoint(void);
u_int bsfl(u_int mask);
u_int bsrl(u_int mask);
void clflush(u_long addr);
void clts(void);
void cpuid_count(u_int ax, u_int cx, u_int *p);
void disable_intr(void);
void do_cpuid(u_int ax, u_int *p);
void enable_intr(void);

10
sys/i386/include/cpufunc.h
View File

@ -96,6 +96,13 @@ clflush(u_long addr)
__asm __volatile("clflush %0" : : "m" (*(char *)addr));
}
static __inline void
clts(void)
{
__asm __volatile("clts");
}
static __inline void
disable_intr(void)
{
@ -688,6 +695,9 @@ intr_restore(register_t eflags)
int breakpoint(void);
u_int bsfl(u_int mask);
u_int bsrl(u_int mask);
void clflush(u_long addr);
void clts(void);
void cpuid_count(u_int ax, u_int cx, u_int *p);
void disable_intr(void);
void do_cpuid(u_int ax, u_int *p);
void enable_intr(void);

19
sys/i386/isa/npx.c
View File

@ -100,15 +100,6 @@ __FBSDID("$FreeBSD$");
#define fxrstor(addr) __asm __volatile("fxrstor %0" : : "m" (*(addr)))
#define fxsave(addr) __asm __volatile("fxsave %0" : "=m" (*(addr)))
#endif
#ifdef XEN
#define start_emulating() (HYPERVISOR_fpu_taskswitch(1))
#define stop_emulating() (HYPERVISOR_fpu_taskswitch(0))
#else
#define start_emulating() __asm __volatile( \
"smsw %%ax; orb %0,%%al; lmsw %%ax" \
: : "n" (CR0_TS) : "ax")
#define stop_emulating() __asm __volatile("clts")
#endif
#else /* !(__GNUCLIKE_ASM && !lint) */
void fldcw(u_short cw);
@ -123,11 +114,17 @@ void frstor(caddr_t addr);
void fxsave(caddr_t addr);
void fxrstor(caddr_t addr);
#endif
void start_emulating(void);
void stop_emulating(void);
#endif /* __GNUCLIKE_ASM && !lint */
#ifdef XEN
#define start_emulating() (HYPERVISOR_fpu_taskswitch(1))
#define stop_emulating() (HYPERVISOR_fpu_taskswitch(0))
#else
#define start_emulating() load_cr0(rcr0() | CR0_TS)
#define stop_emulating() clts()
#endif
#ifdef CPU_ENABLE_SSE
#define GET_FPU_CW(thread) \
(cpu_fxsr ? \