x86/fpu/math-emu: Add support for FCMOVcc insns

Run-tested by booting with "no387 nofxsr" and running test
program:

  [RUN]   Testing fcmovCC instructions
  [OK]    fcmovCC

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1442588010-20055-3-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/math-emu/fpu_aux.c b/arch/x86/math-emu/fpu_aux.c
index dd76a05..024f6e9 100644 (file)
--- a/arch/x86/math-emu/fpu_aux.c
+++ b/arch/x86/math-emu/fpu_aux.c
@@ -169,6 +169,76 @@ void fxch_i(void)
        fpu_tag_word = tag_word;
 }
 
+static void fcmovCC(void)
+{
+       /* fcmovCC st(i) */
+       int i = FPU_rm;
+       FPU_REG *st0_ptr = &st(0);
+       FPU_REG *sti_ptr = &st(i);
+       long tag_word = fpu_tag_word;
+       int regnr = top & 7;
+       int regnri = (top + i) & 7;
+       u_char sti_tag = (tag_word >> (regnri * 2)) & 3;
+
+       if (sti_tag == TAG_Empty) {
+               FPU_stack_underflow();
+               clear_C1();
+               return;
+       }
+       reg_copy(sti_ptr, st0_ptr);
+       tag_word &= ~(3 << (regnr * 2));
+       tag_word |= (sti_tag << (regnr * 2));
+       fpu_tag_word = tag_word;
+}
+
+void fcmovb(void)
+{
+       if (FPU_EFLAGS & X86_EFLAGS_CF)
+               fcmovCC();
+}
+
+void fcmove(void)
+{
+       if (FPU_EFLAGS & X86_EFLAGS_ZF)
+               fcmovCC();
+}
+
+void fcmovbe(void)
+{
+       if (FPU_EFLAGS & (X86_EFLAGS_CF|X86_EFLAGS_ZF))
+               fcmovCC();
+}
+
+void fcmovu(void)
+{
+       if (FPU_EFLAGS & X86_EFLAGS_PF)
+               fcmovCC();
+}
+
+void fcmovnb(void)
+{
+       if (!(FPU_EFLAGS & X86_EFLAGS_CF))
+               fcmovCC();
+}
+
+void fcmovne(void)
+{
+       if (!(FPU_EFLAGS & X86_EFLAGS_ZF))
+               fcmovCC();
+}
+
+void fcmovnbe(void)
+{
+       if (!(FPU_EFLAGS & (X86_EFLAGS_CF|X86_EFLAGS_ZF)))
+               fcmovCC();
+}
+
+void fcmovnu(void)
+{
+       if (!(FPU_EFLAGS & X86_EFLAGS_PF))
+               fcmovCC();
+}
+
 void ffree_(void)
 {
        /* ffree st(i) */

diff --git a/arch/x86/math-emu/fpu_entry.c b/arch/x86/math-emu/fpu_entry.c
index 4ecf683..e945fed 100644 (file)
--- a/arch/x86/math-emu/fpu_entry.c
+++ b/arch/x86/math-emu/fpu_entry.c
@@ -40,7 +40,7 @@
 
 #define __BAD__ FPU_illegal    /* Illegal on an 80486, causes SIGILL */
 
-/* f(u)comi(p) are enabled if CPUID(1).EDX(15) "cmov" is set */
+/* fcmovCC and f(u)comi(p) are enabled if CPUID(1).EDX(15) "cmov" is set */
 
 /* WARNING: "u" entries are not documented by Intel in their 80486 manual
    and may not work on FPU clones or later Intel FPUs.
@@ -49,13 +49,13 @@
 static FUNC const st_instr_table[64] = {
 /* Opcode:     d8              d9              da              db */
 /*             dc              dd              de              df */
-/* c0..7 */    fadd__,         fld_i_,         __BAD__,        __BAD__,
+/* c0..7 */    fadd__,         fld_i_,         fcmovb,         fcmovnb,
 /* c0..7 */    fadd_i,         ffree_,         faddp_,         ffreep,/*u*/
-/* c8..f */    fmul__,         fxch_i,         __BAD__,        __BAD__,
+/* c8..f */    fmul__,         fxch_i,         fcmove,         fcmovne,
 /* c8..f */    fmul_i,         fxch_i,/*u*/    fmulp_,         fxch_i,/*u*/
-/* d0..7 */    fcom_st,        fp_nop,         __BAD__,        __BAD__,
+/* d0..7 */    fcom_st,        fp_nop,         fcmovbe,        fcmovnbe,
 /* d0..7 */    fcom_st,/*u*/   fst_i_,         fcompst,/*u*/   fstp_i,/*u*/
-/* d8..f */    fcompst,        fstp_i,/*u*/    __BAD__,        __BAD__,
+/* d8..f */    fcompst,        fstp_i,/*u*/    fcmovu,         fcmovnu,
 /* d8..f */    fcompst,/*u*/   fstp_i,         fcompp,         fstp_i,/*u*/
 /* e0..7 */    fsub__,         FPU_etc,        __BAD__,        finit_,
 /* e0..7 */    fsubri,         fucom_,         fsubrp,         fstsw_,
@@ -80,10 +80,10 @@ static FUNC const st_instr_table[64] = {
 
 static u_char const type_table[64] = {
 /* Opcode:     d8      d9      da      db      dc      dd      de      df */
-/* c0..7 */    _REGI_, _NONE_, _null_, _null_, _REGIi, _REGi_, _REGIp, _REGi_,
-/* c8..f */    _REGI_, _REGIn, _null_, _null_, _REGIi, _REGI_, _REGIp, _REGI_,
-/* d0..7 */    _REGIc, _NONE_, _null_, _null_, _REGIc, _REG0_, _REGIc, _REG0_,
-/* d8..f */    _REGIc, _REG0_, _null_, _null_, _REGIc, _REG0_, _REGIc, _REG0_,
+/* c0..7 */    _REGI_, _NONE_, _REGIn, _REGIn, _REGIi, _REGi_, _REGIp, _REGi_,
+/* c8..f */    _REGI_, _REGIn, _REGIn, _REGIn, _REGIi, _REGI_, _REGIp, _REGI_,
+/* d0..7 */    _REGIc, _NONE_, _REGIn, _REGIn, _REGIc, _REG0_, _REGIc, _REG0_,
+/* d8..f */    _REGIc, _REG0_, _REGIn, _REGIn, _REGIc, _REG0_, _REGIc, _REG0_,
 /* e0..7 */    _REGI_, _NONE_, _null_, _NONE_, _REGIi, _REGIc, _REGIp, _NONE_,
 /* e8..f */    _REGI_, _NONE_, _REGIc, _REGIc, _REGIi, _REGIc, _REGIp, _REGIc,
 /* f0..7 */    _REGI_, _NONE_, _null_, _REGIc, _REGIi, _null_, _REGIp, _REGIc,

diff --git a/arch/x86/math-emu/fpu_proto.h b/arch/x86/math-emu/fpu_proto.h
index 1f8d130..caff438 100644 (file)
--- a/arch/x86/math-emu/fpu_proto.h
+++ b/arch/x86/math-emu/fpu_proto.h
@@ -46,6 +46,14 @@ extern void fstsw_(void);
 extern void fp_nop(void);
 extern void fld_i_(void);
 extern void fxch_i(void);
+extern void fcmovb(void);
+extern void fcmove(void);
+extern void fcmovbe(void);
+extern void fcmovu(void);
+extern void fcmovnb(void);
+extern void fcmovne(void);
+extern void fcmovnbe(void);
+extern void fcmovnu(void);
 extern void ffree_(void);
 extern void ffreep(void);
 extern void fst_i_(void);