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Date: Fri, 18 Sep 2015 16:53:30 +0200
From: Denys Vlasenko <dvlasenk@...hat.com>
To: Ingo Molnar <mingo@...nel.org>
Cc: Denys Vlasenko <dvlasenk@...hat.com>,
Borislav Petkov <bp@...en8.de>,
"H. Peter Anvin" <hpa@...or.com>,
Andy Lutomirski <luto@...capital.net>,
Kees Cook <keescook@...omium.org>, x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH 3/3] x86/math-emu: Add support for FCMOVcc insns
Run-tested by booting with "no387 nofxsr" and running test program:
# ./test_FCMOV
[RUN] Testing fcmovCC instructions
[OK] fcmovCC
Signed-off-by: Denys Vlasenko <dvlasenk@...hat.com>
CC: Ingo Molnar <mingo@...nel.org>
CC: Borislav Petkov <bp@...en8.de>
CC: "H. Peter Anvin" <hpa@...or.com>
CC: Andy Lutomirski <luto@...capital.net>
CC: Kees Cook <keescook@...omium.org>
CC: x86@...nel.org
CC: linux-kernel@...r.kernel.org
---
arch/x86/math-emu/fpu_aux.c | 70 +++++++++++++++++++++++++++++++++++++++++++
arch/x86/math-emu/fpu_entry.c | 18 +++++------
arch/x86/math-emu/fpu_proto.h | 8 +++++
3 files changed, 87 insertions(+), 9 deletions(-)
diff --git a/arch/x86/math-emu/fpu_aux.c b/arch/x86/math-emu/fpu_aux.c
index dd76a05..024f6e9 100644
--- 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
--- 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
--- 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);
--
1.8.1.4
--
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