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Date: Thu, 27 Aug 2015 20:15:29 +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 2/3] x86/math-emu: Add support for FCMOVcc and F[U]COMI[P] insns
Only compile-tested.
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 | 49 +++++++++------
arch/x86/math-emu/fpu_proto.h | 12 ++++
arch/x86/math-emu/reg_compare.c | 128 ++++++++++++++++++++++++++++++++++++++++
4 files changed, 241 insertions(+), 18 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 929b1d5..77c6505 100644
--- a/arch/x86/math-emu/fpu_entry.c
+++ b/arch/x86/math-emu/fpu_entry.c
@@ -40,10 +40,10 @@
#define __BAD__ FPU_illegal /* Illegal on an 80486, causes SIGILL */
-/* WARNING: These codes are not documented by Intel in their 80486 manual
+/* WARNING: These codes are not all documented by Intel in their 80486 manual
and may not work on FPU clones or later Intel FPUs. */
-/* Changes to support the un-doc codes provided by Linus Torvalds. */
+/* Changes to support the un-documented instructions provided by Linus Torvalds. */
#define _d9_d8_ fstp_i /* unofficial code (19) */
#define _dc_d0_ fcom_st /* unofficial code (14) */
@@ -55,15 +55,27 @@
#define _df_d0_ fstp_i /* unofficial code (17) */
#define _df_d8_ fstp_i /* unofficial code (1f) */
+/* fcmovCC and f(u)comi(p) are enabled if CPUID(1).EDX(15) "cmov" is set */
+
static FUNC const st_instr_table[64] = {
- fadd__, fld_i_, __BAD__, __BAD__, fadd_i, ffree_, faddp_, _df_c0_,
- fmul__, fxch_i, __BAD__, __BAD__, fmul_i, _dd_c8_, fmulp_, _df_c8_,
- fcom_st, fp_nop, __BAD__, __BAD__, _dc_d0_, fst_i_, _de_d0_, _df_d0_,
- fcompst, _d9_d8_, __BAD__, __BAD__, _dc_d8_, fstp_i, fcompp, _df_d8_,
- fsub__, FPU_etc, __BAD__, finit_, fsubri, fucom_, fsubrp, fstsw_,
- fsubr_, fconst, fucompp, __BAD__, fsub_i, fucomp, fsubp_, __BAD__,
- fdiv__, FPU_triga, __BAD__, __BAD__, fdivri, __BAD__, fdivrp, __BAD__,
- fdivr_, FPU_trigb, __BAD__, __BAD__, fdiv_i, __BAD__, fdivp_, __BAD__,
+/* Opcode: d8 d9 da db */
+/* dc dd de df */
+/* c0..7 */ fadd__, fld_i_, fcmovb, fcmovnb,
+/* c0..7 */ fadd_i, ffree_, faddp_, _df_c0_,
+/* c8..f */ fmul__, fxch_i, fcmove, fcmovne,
+/* c8..f */ fmul_i, _dd_c8_, fmulp_, _df_c8_,
+/* d0..7 */ fcom_st, fp_nop, fcmovbe, fcmovnbe,
+/* d0..7 */ _dc_d0_, fst_i_, _de_d0_, _df_d0_,
+/* d8..f */ fcompst, _d9_d8_, fcmovu, fcmovnu,
+/* d8..f */ _dc_d8_, fstp_i, fcompp, _df_d8_,
+/* e0..7 */ fsub__, FPU_etc, __BAD__, finit_,
+/* e0..7 */ fsubri, fucom_, fsubrp, fstsw_,
+/* e8..f */ fsubr_, fconst, fucompp, fucomi_,
+/* e8..f */ fsub_i, fucomp, fsubp_, fucomip,
+/* f0..7 */ fdiv__, FPU_triga, __BAD__, fcomi_,
+/* f0..7 */ fdivri, __BAD__, fdivrp, fcomip,
+/* f8..f */ fdivr_, FPU_trigb, __BAD__, __BAD__,
+/* f8..f */ fdiv_i, __BAD__, fdivp_, __BAD__,
};
#define _NONE_ 0 /* Take no special action */
@@ -78,14 +90,15 @@ static FUNC const st_instr_table[64] = {
#define _REGIn 0 /* Uses st(0) and st(rm), but handle checks later */
static u_char const type_table[64] = {
- _REGI_, _NONE_, _null_, _null_, _REGIi, _REGi_, _REGIp, _REGi_,
- _REGI_, _REGIn, _null_, _null_, _REGIi, _REGI_, _REGIp, _REGI_,
- _REGIc, _NONE_, _null_, _null_, _REGIc, _REG0_, _REGIc, _REG0_,
- _REGIc, _REG0_, _null_, _null_, _REGIc, _REG0_, _REGIc, _REG0_,
- _REGI_, _NONE_, _null_, _NONE_, _REGIi, _REGIc, _REGIp, _NONE_,
- _REGI_, _NONE_, _REGIc, _null_, _REGIi, _REGIc, _REGIp, _null_,
- _REGI_, _NONE_, _null_, _null_, _REGIi, _null_, _REGIp, _null_,
- _REGI_, _NONE_, _null_, _null_, _REGIi, _null_, _REGIp, _null_
+/* Opcode: d8 d9 da db dc dd de df */
+/* 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,
+/* f8..f */ _REGI_, _NONE_, _null_, _null_, _REGIi, _null_, _REGIp, _null_,
};
#ifdef RE_ENTRANT_CHECKING
diff --git a/arch/x86/math-emu/fpu_proto.h b/arch/x86/math-emu/fpu_proto.h
index 9779df4..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);
@@ -108,6 +116,10 @@ extern void fcompp(void);
extern void fucom_(void);
extern void fucomp(void);
extern void fucompp(void);
+extern void fcomi_(void);
+extern void fcomip(void);
+extern void fucomi_(void);
+extern void fucomip(void);
/* reg_constant.c */
extern void fconst(void);
/* reg_ld_str.c */
diff --git a/arch/x86/math-emu/reg_compare.c b/arch/x86/math-emu/reg_compare.c
index ecce55f..b77360f 100644
--- a/arch/x86/math-emu/reg_compare.c
+++ b/arch/x86/math-emu/reg_compare.c
@@ -249,6 +249,54 @@ static int compare_st_st(int nr)
return 0;
}
+static int compare_i_st_st(int nr)
+{
+ int f, c;
+ FPU_REG *st_ptr;
+
+ if (!NOT_EMPTY(0) || !NOT_EMPTY(nr)) {
+ FPU_EFLAGS |= (X86_EFLAGS_ZF | X86_EFLAGS_PF | X86_EFLAGS_CF);
+ /* Stack fault */
+ EXCEPTION(EX_StackUnder);
+ return !(control_word & CW_Invalid);
+ }
+
+ partial_status &= ~SW_C0;
+ st_ptr = &st(nr);
+ c = compare(st_ptr, FPU_gettagi(nr));
+ if (c & COMP_NaN) {
+ FPU_EFLAGS |= (X86_EFLAGS_ZF | X86_EFLAGS_PF | X86_EFLAGS_CF);
+ EXCEPTION(EX_Invalid);
+ return !(control_word & CW_Invalid);
+ }
+
+ switch (c & 7) {
+ case COMP_A_lt_B:
+ f = X86_EFLAGS_CF;
+ break;
+ case COMP_A_eq_B:
+ f = X86_EFLAGS_ZF;
+ break;
+ case COMP_A_gt_B:
+ f = 0;
+ break;
+ case COMP_No_Comp:
+ f = X86_EFLAGS_ZF | X86_EFLAGS_PF | X86_EFLAGS_CF;
+ break;
+#ifdef PARANOID
+ default:
+ EXCEPTION(EX_INTERNAL | 0x122);
+ f = 0;
+ break;
+#endif /* PARANOID */
+ }
+ FPU_EFLAGS = (FPU_EFLAGS & ~(X86_EFLAGS_ZF | X86_EFLAGS_PF | X86_EFLAGS_CF)) | f;
+ if (c & COMP_Denormal) {
+ return denormal_operand() < 0;
+ }
+ return 0;
+}
+
static int compare_u_st_st(int nr)
{
int f = 0, c;
@@ -299,6 +347,58 @@ static int compare_u_st_st(int nr)
return 0;
}
+static int compare_ui_st_st(int nr)
+{
+ int f = 0, c;
+ FPU_REG *st_ptr;
+
+ if (!NOT_EMPTY(0) || !NOT_EMPTY(nr)) {
+ FPU_EFLAGS |= (X86_EFLAGS_ZF | X86_EFLAGS_PF | X86_EFLAGS_CF);
+ /* Stack fault */
+ EXCEPTION(EX_StackUnder);
+ return !(control_word & CW_Invalid);
+ }
+
+ partial_status &= ~SW_C0;
+ st_ptr = &st(nr);
+ c = compare(st_ptr, FPU_gettagi(nr));
+ if (c & COMP_NaN) {
+ FPU_EFLAGS |= (X86_EFLAGS_ZF | X86_EFLAGS_PF | X86_EFLAGS_CF);
+ if (c & COMP_SNaN) { /* This is the only difference between
+ un-ordered and ordinary comparisons */
+ EXCEPTION(EX_Invalid);
+ return !(control_word & CW_Invalid);
+ }
+ return 0;
+ }
+
+ switch (c & 7) {
+ case COMP_A_lt_B:
+ f = X86_EFLAGS_CF;
+ break;
+ case COMP_A_eq_B:
+ f = X86_EFLAGS_ZF;
+ break;
+ case COMP_A_gt_B:
+ f = 0;
+ break;
+ case COMP_No_Comp:
+ f = X86_EFLAGS_ZF | X86_EFLAGS_PF | X86_EFLAGS_CF;
+ break;
+#ifdef PARANOID
+ default:
+ EXCEPTION(EX_INTERNAL | 0x123);
+ f = 0;
+ break;
+#endif /* PARANOID */
+ }
+ FPU_EFLAGS = (FPU_EFLAGS & ~(X86_EFLAGS_ZF | X86_EFLAGS_PF | X86_EFLAGS_CF)) | f;
+ if (c & COMP_Denormal) {
+ return denormal_operand() < 0;
+ }
+ return 0;
+}
+
/*---------------------------------------------------------------------------*/
void fcom_st(void)
@@ -348,3 +448,31 @@ void fucompp(void)
} else
FPU_illegal();
}
+
+/* P6+ compare-to-EFLAGS ops */
+
+void fcomi_(void)
+{
+ /* fcomi st(i) */
+ compare_i_st_st(FPU_rm);
+}
+
+void fcomip(void)
+{
+ /* fcomip st(i) */
+ if (!compare_i_st_st(FPU_rm))
+ FPU_pop();
+}
+
+void fucomi_(void)
+{
+ /* fucomi st(i) */
+ compare_ui_st_st(FPU_rm);
+}
+
+void fucomip(void)
+{
+ /* fucomip st(i) */
+ if (!compare_ui_st_st(FPU_rm))
+ FPU_pop();
+}
--
1.8.1.4
--
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