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authorRalf Baechle <ralf@linux-mips.org>2008-10-28 13:38:42 -0400
committerRalf Baechle <ralf@linux-mips.org>2008-10-30 10:44:34 -0400
commitba3049ed4086737dab200b6087138a4b8e06915d (patch)
tree78a665064e6cc288bb34ef20cd543c2feb204838 /arch/mips
parent076c6e4f4d81113615f50e5bc2c569f628bcd54a (diff)
MIPS: Switch FPU emulator trap to BREAK instruction.
Arguably using the address error handler has always been ugly. But with processors that handle unaligned loads and stores in hardware the current mechanism ceases to work so switch it to a BREAK instruction and allocate break code 514 to the FPU emulator. Yoichi Yuasa provided a build fix for CONFIG_BUG=n. Signed-off-by: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
Diffstat (limited to 'arch/mips')
-rw-r--r--arch/mips/include/asm/break.h1
-rw-r--r--arch/mips/include/asm/fpu_emulator.h17
-rw-r--r--arch/mips/kernel/traps.c16
-rw-r--r--arch/mips/kernel/unaligned.c12
-rw-r--r--arch/mips/math-emu/cp1emu.c4
-rw-r--r--arch/mips/math-emu/dsemul.c7
-rw-r--r--arch/mips/math-emu/dsemul.h17
7 files changed, 37 insertions, 37 deletions
diff --git a/arch/mips/include/asm/break.h b/arch/mips/include/asm/break.h
index 25b980c91e7e..44437ed765e8 100644
--- a/arch/mips/include/asm/break.h
+++ b/arch/mips/include/asm/break.h
@@ -29,6 +29,7 @@
29#define _BRK_THREADBP 11 /* For threads, user bp (used by debuggers) */ 29#define _BRK_THREADBP 11 /* For threads, user bp (used by debuggers) */
30#define BRK_BUG 512 /* Used by BUG() */ 30#define BRK_BUG 512 /* Used by BUG() */
31#define BRK_KDB 513 /* Used in KDB_ENTER() */ 31#define BRK_KDB 513 /* Used in KDB_ENTER() */
32#define BRK_MEMU 514 /* Used by FPU emulator */
32#define BRK_MULOVF 1023 /* Multiply overflow */ 33#define BRK_MULOVF 1023 /* Multiply overflow */
33 34
34#endif /* __ASM_BREAK_H */ 35#endif /* __ASM_BREAK_H */
diff --git a/arch/mips/include/asm/fpu_emulator.h b/arch/mips/include/asm/fpu_emulator.h
index 2731c38bd7ae..e5189572956c 100644
--- a/arch/mips/include/asm/fpu_emulator.h
+++ b/arch/mips/include/asm/fpu_emulator.h
@@ -23,6 +23,9 @@
23#ifndef _ASM_FPU_EMULATOR_H 23#ifndef _ASM_FPU_EMULATOR_H
24#define _ASM_FPU_EMULATOR_H 24#define _ASM_FPU_EMULATOR_H
25 25
26#include <asm/break.h>
27#include <asm/inst.h>
28
26struct mips_fpu_emulator_stats { 29struct mips_fpu_emulator_stats {
27 unsigned int emulated; 30 unsigned int emulated;
28 unsigned int loads; 31 unsigned int loads;
@@ -34,4 +37,18 @@ struct mips_fpu_emulator_stats {
34 37
35extern struct mips_fpu_emulator_stats fpuemustats; 38extern struct mips_fpu_emulator_stats fpuemustats;
36 39
40extern int mips_dsemul(struct pt_regs *regs, mips_instruction ir,
41 unsigned long cpc);
42extern int do_dsemulret(struct pt_regs *xcp);
43
44/*
45 * Instruction inserted following the badinst to further tag the sequence
46 */
47#define BD_COOKIE 0x0000bd36 /* tne $0, $0 with baggage */
48
49/*
50 * Break instruction with special math emu break code set
51 */
52#define BREAK_MATH (0x0000000d | (BRK_MEMU << 16))
53
37#endif /* _ASM_FPU_EMULATOR_H */ 54#endif /* _ASM_FPU_EMULATOR_H */
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 3f6de76d485d..353056110f2b 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -32,6 +32,7 @@
32#include <asm/cpu.h> 32#include <asm/cpu.h>
33#include <asm/dsp.h> 33#include <asm/dsp.h>
34#include <asm/fpu.h> 34#include <asm/fpu.h>
35#include <asm/fpu_emulator.h>
35#include <asm/mipsregs.h> 36#include <asm/mipsregs.h>
36#include <asm/mipsmtregs.h> 37#include <asm/mipsmtregs.h>
37#include <asm/module.h> 38#include <asm/module.h>
@@ -722,6 +723,21 @@ static void do_trap_or_bp(struct pt_regs *regs, unsigned int code,
722 die_if_kernel("Kernel bug detected", regs); 723 die_if_kernel("Kernel bug detected", regs);
723 force_sig(SIGTRAP, current); 724 force_sig(SIGTRAP, current);
724 break; 725 break;
726 case BRK_MEMU:
727 /*
728 * Address errors may be deliberately induced by the FPU
729 * emulator to retake control of the CPU after executing the
730 * instruction in the delay slot of an emulated branch.
731 *
732 * Terminate if exception was recognized as a delay slot return
733 * otherwise handle as normal.
734 */
735 if (do_dsemulret(regs))
736 return;
737
738 die_if_kernel("Math emu break/trap", regs);
739 force_sig(SIGTRAP, current);
740 break;
725 default: 741 default:
726 scnprintf(b, sizeof(b), "%s instruction in kernel code", str); 742 scnprintf(b, sizeof(b), "%s instruction in kernel code", str);
727 die_if_kernel(b, regs); 743 die_if_kernel(b, regs);
diff --git a/arch/mips/kernel/unaligned.c b/arch/mips/kernel/unaligned.c
index 20709669e592..bf4c4a979abb 100644
--- a/arch/mips/kernel/unaligned.c
+++ b/arch/mips/kernel/unaligned.c
@@ -499,22 +499,10 @@ sigill:
499 499
500asmlinkage void do_ade(struct pt_regs *regs) 500asmlinkage void do_ade(struct pt_regs *regs)
501{ 501{
502 extern int do_dsemulret(struct pt_regs *);
503 unsigned int __user *pc; 502 unsigned int __user *pc;
504 mm_segment_t seg; 503 mm_segment_t seg;
505 504
506 /* 505 /*
507 * Address errors may be deliberately induced by the FPU emulator to
508 * retake control of the CPU after executing the instruction in the
509 * delay slot of an emulated branch.
510 */
511 /* Terminate if exception was recognized as a delay slot return */
512 if (do_dsemulret(regs))
513 return;
514
515 /* Otherwise handle as normal */
516
517 /*
518 * Did we catch a fault trying to load an instruction? 506 * Did we catch a fault trying to load an instruction?
519 * Or are we running in MIPS16 mode? 507 * Or are we running in MIPS16 mode?
520 */ 508 */
diff --git a/arch/mips/math-emu/cp1emu.c b/arch/mips/math-emu/cp1emu.c
index 7ec0b217dfd3..890f77927d62 100644
--- a/arch/mips/math-emu/cp1emu.c
+++ b/arch/mips/math-emu/cp1emu.c
@@ -48,7 +48,6 @@
48#include <asm/branch.h> 48#include <asm/branch.h>
49 49
50#include "ieee754.h" 50#include "ieee754.h"
51#include "dsemul.h"
52 51
53/* Strap kernel emulator for full MIPS IV emulation */ 52/* Strap kernel emulator for full MIPS IV emulation */
54 53
@@ -346,9 +345,6 @@ static int cop1Emulate(struct pt_regs *xcp, struct mips_fpu_struct *ctx)
346 /* cop control register rd -> gpr[rt] */ 345 /* cop control register rd -> gpr[rt] */
347 u32 value; 346 u32 value;
348 347
349 if (ir == CP1UNDEF) {
350 return do_dsemulret(xcp);
351 }
352 if (MIPSInst_RD(ir) == FPCREG_CSR) { 348 if (MIPSInst_RD(ir) == FPCREG_CSR) {
353 value = ctx->fcr31; 349 value = ctx->fcr31;
354 value = (value & ~0x3) | mips_rm[value & 0x3]; 350 value = (value & ~0x3) | mips_rm[value & 0x3];
diff --git a/arch/mips/math-emu/dsemul.c b/arch/mips/math-emu/dsemul.c
index 653e325849e4..df7b9d928efc 100644
--- a/arch/mips/math-emu/dsemul.c
+++ b/arch/mips/math-emu/dsemul.c
@@ -18,7 +18,6 @@
18#include <asm/fpu_emulator.h> 18#include <asm/fpu_emulator.h>
19 19
20#include "ieee754.h" 20#include "ieee754.h"
21#include "dsemul.h"
22 21
23/* Strap kernel emulator for full MIPS IV emulation */ 22/* Strap kernel emulator for full MIPS IV emulation */
24 23
@@ -94,7 +93,7 @@ int mips_dsemul(struct pt_regs *regs, mips_instruction ir, unsigned long cpc)
94 return SIGBUS; 93 return SIGBUS;
95 94
96 err = __put_user(ir, &fr->emul); 95 err = __put_user(ir, &fr->emul);
97 err |= __put_user((mips_instruction)BADINST, &fr->badinst); 96 err |= __put_user((mips_instruction)BREAK_MATH, &fr->badinst);
98 err |= __put_user((mips_instruction)BD_COOKIE, &fr->cookie); 97 err |= __put_user((mips_instruction)BD_COOKIE, &fr->cookie);
99 err |= __put_user(cpc, &fr->epc); 98 err |= __put_user(cpc, &fr->epc);
100 99
@@ -130,13 +129,13 @@ int do_dsemulret(struct pt_regs *xcp)
130 /* 129 /*
131 * Do some sanity checking on the stackframe: 130 * Do some sanity checking on the stackframe:
132 * 131 *
133 * - Is the instruction pointed to by the EPC an BADINST? 132 * - Is the instruction pointed to by the EPC an BREAK_MATH?
134 * - Is the following memory word the BD_COOKIE? 133 * - Is the following memory word the BD_COOKIE?
135 */ 134 */
136 err = __get_user(insn, &fr->badinst); 135 err = __get_user(insn, &fr->badinst);
137 err |= __get_user(cookie, &fr->cookie); 136 err |= __get_user(cookie, &fr->cookie);
138 137
139 if (unlikely(err || (insn != BADINST) || (cookie != BD_COOKIE))) { 138 if (unlikely(err || (insn != BREAK_MATH) || (cookie != BD_COOKIE))) {
140 fpuemustats.errors++; 139 fpuemustats.errors++;
141 return 0; 140 return 0;
142 } 141 }
diff --git a/arch/mips/math-emu/dsemul.h b/arch/mips/math-emu/dsemul.h
deleted file mode 100644
index 091f0e76730f..000000000000
--- a/arch/mips/math-emu/dsemul.h
+++ /dev/null
@@ -1,17 +0,0 @@
1extern int mips_dsemul(struct pt_regs *regs, mips_instruction ir, unsigned long cpc);
2extern int do_dsemulret(struct pt_regs *xcp);
3
4/* Instruction which will always cause an address error */
5#define AdELOAD 0x8c000001 /* lw $0,1($0) */
6/* Instruction which will plainly cause a CP1 exception when FPU is disabled */
7#define CP1UNDEF 0x44400001 /* cfc1 $0,$0 undef */
8
9/* Instruction inserted following the badinst to further tag the sequence */
10#define BD_COOKIE 0x0000bd36 /* tne $0,$0 with baggage */
11
12/* Setup which instruction to use for trampoline */
13#ifdef STANDALONE_EMULATOR
14#define BADINST CP1UNDEF
15#else
16#define BADINST AdELOAD
17#endif