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sh: math-emu support
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This implements initial math-emu support, aimed primarily at SH-3.

Signed-off-by: Takashi YOSHII <takasi-y@ops.dti.ne.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
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Takashi YOSHII authored and Paul Mundt committed Sep 27, 2006
1 parent 317a610 commit 4b56568
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Showing 7 changed files with 918 additions and 39 deletions.
9 changes: 9 additions & 0 deletions arch/sh/Kconfig
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Expand Up @@ -339,6 +339,15 @@ config SH_FPU

This option must be set in order to enable the FPU.

config SH_FPU_EMU
bool "FPU emulation support"
depends on !SH_FPU && EXPERIMENTAL
default n
help
Selecting this option will enable support for software FPU emulation.
Most SH-3 users will want to say Y here, whereas most SH-4 users will
want to say N.

config SH_DSP
bool "DSP support"
depends on !CPU_SH4
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1 change: 1 addition & 0 deletions arch/sh/Makefile
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Expand Up @@ -79,6 +79,7 @@ head-y := arch/sh/kernel/head.o arch/sh/kernel/init_task.o
LIBGCC := $(shell $(CC) $(CFLAGS) -print-libgcc-file-name)

core-y += arch/sh/kernel/ arch/sh/mm/
core-$(CONFIG_SH_FPU_EMU) += arch/sh/math-emu/

# Boards
machdir-$(CONFIG_SH_SOLUTION_ENGINE) := se/770x
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164 changes: 125 additions & 39 deletions arch/sh/kernel/traps.c
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Expand Up @@ -36,40 +36,15 @@

#ifdef CONFIG_SH_KGDB
#include <asm/kgdb.h>
#define CHK_REMOTE_DEBUG(regs) \
{ \
if ((kgdb_debug_hook != (kgdb_debug_hook_t *) NULL) && (!user_mode(regs))) \
{ \
(*kgdb_debug_hook)(regs); \
} \
#define CHK_REMOTE_DEBUG(regs) \
{ \
if (kgdb_debug_hook && !user_mode(regs))\
(*kgdb_debug_hook)(regs); \
}
#else
#define CHK_REMOTE_DEBUG(regs)
#endif

#define DO_ERROR(trapnr, signr, str, name, tsk) \
asmlinkage void do_##name(unsigned long r4, unsigned long r5, \
unsigned long r6, unsigned long r7, \
struct pt_regs regs) \
{ \
unsigned long error_code; \
\
/* Check if it's a DSP instruction */ \
if (is_dsp_inst(&regs)) { \
/* Enable DSP mode, and restart instruction. */ \
regs.sr |= SR_DSP; \
return; \
} \
\
asm volatile("stc r2_bank, %0": "=r" (error_code)); \
local_irq_enable(); \
tsk->thread.error_code = error_code; \
tsk->thread.trap_no = trapnr; \
CHK_REMOTE_DEBUG(&regs); \
force_sig(signr, tsk); \
die_if_no_fixup(str,&regs,error_code); \
}

#ifdef CONFIG_CPU_SH2
#define TRAP_RESERVED_INST 4
#define TRAP_ILLEGAL_SLOT_INST 6
Expand Down Expand Up @@ -575,8 +550,117 @@ int is_dsp_inst(struct pt_regs *regs)
#define is_dsp_inst(regs) (0)
#endif /* CONFIG_SH_DSP */

DO_ERROR(TRAP_RESERVED_INST, SIGILL, "reserved instruction", reserved_inst, current)
DO_ERROR(TRAP_ILLEGAL_SLOT_INST, SIGILL, "illegal slot instruction", illegal_slot_inst, current)
extern int do_fpu_inst(unsigned short, struct pt_regs*);

asmlinkage void do_reserved_inst(unsigned long r4, unsigned long r5,
unsigned long r6, unsigned long r7,
struct pt_regs regs)
{
unsigned long error_code;
struct task_struct *tsk = current;

#ifdef CONFIG_SH_FPU_EMU
unsigned short inst;
int err;

get_user(inst, (unsigned short*)regs.pc);

err = do_fpu_inst(inst, &regs);
if (!err) {
regs.pc += 2;
return;
}
/* not a FPU inst. */
#endif

#ifdef CONFIG_SH_DSP
/* Check if it's a DSP instruction */
if (is_dsp_inst(&regs)) {
/* Enable DSP mode, and restart instruction. */
regs.sr |= SR_DSP;
return;
}
#endif

asm volatile("stc r2_bank, %0": "=r" (error_code));
local_irq_enable();
tsk->thread.error_code = error_code;
tsk->thread.trap_no = TRAP_RESERVED_INST;
CHK_REMOTE_DEBUG(&regs);
force_sig(SIGILL, tsk);
die_if_no_fixup("reserved instruction", &regs, error_code);
}

#ifdef CONFIG_SH_FPU_EMU
static int emulate_branch(unsigned short inst, struct pt_regs* regs)
{
/*
* bfs: 8fxx: PC+=d*2+4;
* bts: 8dxx: PC+=d*2+4;
* bra: axxx: PC+=D*2+4;
* bsr: bxxx: PC+=D*2+4 after PR=PC+4;
* braf:0x23: PC+=Rn*2+4;
* bsrf:0x03: PC+=Rn*2+4 after PR=PC+4;
* jmp: 4x2b: PC=Rn;
* jsr: 4x0b: PC=Rn after PR=PC+4;
* rts: 000b: PC=PR;
*/
if ((inst & 0xfd00) == 0x8d00) {
regs->pc += SH_PC_8BIT_OFFSET(inst);
return 0;
}

if ((inst & 0xe000) == 0xa000) {
regs->pc += SH_PC_12BIT_OFFSET(inst);
return 0;
}

if ((inst & 0xf0df) == 0x0003) {
regs->pc += regs->regs[(inst & 0x0f00) >> 8] + 4;
return 0;
}

if ((inst & 0xf0df) == 0x400b) {
regs->pc = regs->regs[(inst & 0x0f00) >> 8];
return 0;
}

if ((inst & 0xffff) == 0x000b) {
regs->pc = regs->pr;
return 0;
}

return 1;
}
#endif

asmlinkage void do_illegal_slot_inst(unsigned long r4, unsigned long r5,
unsigned long r6, unsigned long r7,
struct pt_regs regs)
{
unsigned long error_code;
struct task_struct *tsk = current;
#ifdef CONFIG_SH_FPU_EMU
unsigned short inst;

get_user(inst, (unsigned short *)regs.pc + 1);
if (!do_fpu_inst(inst, &regs)) {
get_user(inst, (unsigned short *)regs.pc);
if (!emulate_branch(inst, &regs))
return;
/* fault in branch.*/
}
/* not a FPU inst. */
#endif

asm volatile("stc r2_bank, %0": "=r" (error_code));
local_irq_enable();
tsk->thread.error_code = error_code;
tsk->thread.trap_no = TRAP_RESERVED_INST;
CHK_REMOTE_DEBUG(&regs);
force_sig(SIGILL, tsk);
die_if_no_fixup("illegal slot instruction", &regs, error_code);
}

asmlinkage void do_exception_error(unsigned long r4, unsigned long r5,
unsigned long r6, unsigned long r7,
Expand Down Expand Up @@ -634,14 +718,16 @@ void __init trap_init(void)
exception_handling_table[TRAP_ILLEGAL_SLOT_INST]
= (void *)do_illegal_slot_inst;

#ifdef CONFIG_CPU_SH4
if (!(cpu_data->flags & CPU_HAS_FPU)) {
/* For SH-4 lacking an FPU, treat floating point instructions
as reserved. */
/* entry 64 corresponds to EXPEVT=0x800 */
exception_handling_table[64] = (void *)do_reserved_inst;
exception_handling_table[65] = (void *)do_illegal_slot_inst;
}
#if defined(CONFIG_CPU_SH4) && !defined(CONFIG_SH_FPU) || \
defined(CONFIG_SH_FPU_EMU)
/*
* For SH-4 lacking an FPU, treat floating point instructions as
* reserved. They'll be handled in the math-emu case, or faulted on
* otherwise.
*/
/* entry 64 corresponds to EXPEVT=0x800 */
exception_handling_table[64] = (void *)do_reserved_inst;
exception_handling_table[65] = (void *)do_illegal_slot_inst;
#endif

/* Setup VBR for boot cpu */
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1 change: 1 addition & 0 deletions arch/sh/math-emu/Makefile
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
obj-y := math.o
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