Discussion:
[uClinux-dev] [PATCH 1/2] m68k: make support for FPU hardware configurable
gerg
2012-02-10 06:14:16 UTC
Permalink
From: Greg Ungerer <gerg at uclinux.org>

The classic m68k code has always supported an FPU (although it may have
been a software emulated one). The non-MMU m68k code has never supported FPU
hardware. To help in merging common code create a configation setting that
signifies if we are builing in FPU support or not.

This switch, CONFIG_FPU, is set as per the current use cases. So it is
always enabled if CONFIG_MMU is set, and disabled otherwise. With a little
extra code it will be possible to disable it on the classic m68k platforms
as well, and to enable it on non-MMU platforms that do have hardware FPU.

Signed-off-by: Greg Ungerer <gerg at uclinux.org>
---
arch/m68k/Kconfig | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index ae413d4..57bf848 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -7,6 +7,7 @@ config M68K
select GENERIC_IRQ_SHOW
select ARCH_HAVE_NMI_SAFE_CMPXCHG if RMW_INSNS
select GENERIC_CPU_DEVICES
+ select FPU if MMU

config RWSEM_GENERIC_SPINLOCK
bool
@@ -67,6 +68,9 @@ config CPU_HAS_NO_MULDIV64
config CPU_HAS_ADDRESS_SPACES
bool

+config FPU
+ bool
+
config HZ
int
default 1000 if CLEOPATRA
--
1.7.0.4
gerg
2012-02-10 06:14:17 UTC
Permalink
From: Greg Ungerer <gerg at uclinux.org>

The MMU and non-MMU varients of the m68k arch process.c code are pretty
much the same. Only a few minor details differ between the two. The
majority of the difference is to deal with having or wanting hardware FPU
support. So merge them back into a single process.c file.

Signed-off-by: Greg Ungerer <gerg at uclinux.org>
---
arch/m68k/kernel/{process_mm.c => process.c} | 19 +-
arch/m68k/kernel/process_no.c | 406 --------------------------
2 files changed, 15 insertions(+), 410 deletions(-)
rename arch/m68k/kernel/{process_mm.c => process.c} (97%)
delete mode 100644 arch/m68k/kernel/process_no.c

diff --git a/arch/m68k/kernel/process_mm.c b/arch/m68k/kernel/process.c
similarity index 97%
rename from arch/m68k/kernel/process_mm.c
rename to arch/m68k/kernel/process.c
index 099283e..f053e24 100644
--- a/arch/m68k/kernel/process_mm.c
+++ b/arch/m68k/kernel/process.c
@@ -144,8 +144,10 @@ int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
"trap #0\n\t" /* Linux/m68k system call */
"tstl %0\n\t" /* child or parent */
"jne 1f\n\t" /* parent - jump */
+#ifdef CONFIG_MMU
"lea %%sp@(%c7),%6\n\t" /* reload current */
"movel %6@,%6\n\t"
+#endif
"movel %3,%%sp at -\n\t" /* push argument */
"jsr %4@\n\t" /* call fn */
"movel %0,%%d1\n\t" /* pass exit value */
@@ -168,11 +170,13 @@ EXPORT_SYMBOL(kernel_thread);

void flush_thread(void)
{
- unsigned long zero = 0;
-
current->thread.fs = __USER_DS;
- if (!FPU_IS_EMU)
+#ifdef CONFIG_FPU
+ if (!FPU_IS_EMU) {
+ unsigned long zero = 0;
asm volatile("frestore %0": :"m" (zero));
+ }
+#endif
}

/*
@@ -184,7 +188,11 @@ void flush_thread(void)

asmlinkage int m68k_fork(struct pt_regs *regs)
{
+#ifdef CONFIG_MMU
return do_fork(SIGCHLD, rdusp(), regs, 0, NULL, NULL);
+#else
+ return -EINVAL;
+#endif
}

asmlinkage int m68k_vfork(struct pt_regs *regs)
@@ -242,6 +250,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
*/
p->thread.fs = get_fs().seg;

+#ifdef CONFIG_FPU
if (!FPU_IS_EMU) {
/* Copy the current fpu state */
asm volatile ("fsave %0" : : "m" (p->thread.fpstate[0]) : "memory");
@@ -271,12 +280,13 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
/* Restore the state in case the fpu was busy */
asm volatile ("frestore %0" : : "m" (p->thread.fpstate[0]));
}
+#endif /* CONFIG_FPU */

return 0;
}

/* Fill in the fpu structure for a core dump. */
-
+#ifdef CONFIG_FPU
int dump_fpu (struct pt_regs *regs, struct user_m68kfp_struct *fpu)
{
char fpustate[216];
@@ -325,6 +335,7 @@ int dump_fpu (struct pt_regs *regs, struct user_m68kfp_struct *fpu)
return 1;
}
EXPORT_SYMBOL(dump_fpu);
+#endif /* CONFIG_FPU */

/*
* sys_execve() executes a new program.
diff --git a/arch/m68k/kernel/process_no.c b/arch/m68k/kernel/process_no.c
deleted file mode 100644
index 5e1078c..0000000
--- a/arch/m68k/kernel/process_no.c
+++ /dev/null
@@ -1,406 +0,0 @@
-/*
- * linux/arch/m68knommu/kernel/process.c
- *
- * Copyright (C) 1995 Hamish Macdonald
- *
- * 68060 fixes by Jesper Skov
- *
- * uClinux changes
- * Copyright (C) 2000-2002, David McCullough <davidm at snapgear.com>
- */
-
-/*
- * This file handles the architecture-dependent parts of process handling..
- */
-
-#include <linux/module.h>
-#include <linux/errno.h>
-#include <linux/sched.h>
-#include <linux/kernel.h>
-#include <linux/mm.h>
-#include <linux/smp.h>
-#include <linux/stddef.h>
-#include <linux/unistd.h>
-#include <linux/ptrace.h>
-#include <linux/user.h>
-#include <linux/interrupt.h>
-#include <linux/reboot.h>
-#include <linux/fs.h>
-#include <linux/slab.h>
-
-#include <asm/uaccess.h>
-#include <asm/system.h>
-#include <asm/traps.h>
-#include <asm/machdep.h>
-#include <asm/setup.h>
-#include <asm/pgtable.h>
-
-asmlinkage void ret_from_fork(void);
-
-/*
- * The following aren't currently used.
- */
-void (*pm_idle)(void);
-EXPORT_SYMBOL(pm_idle);
-
-void (*pm_power_off)(void);
-EXPORT_SYMBOL(pm_power_off);
-
-/*
- * The idle loop on an m68knommu..
- */
-static void default_idle(void)
-{
- local_irq_disable();
- while (!need_resched()) {
- /* This stop will re-enable interrupts */
- __asm__("stop #0x2000" : : : "cc");
- local_irq_disable();
- }
- local_irq_enable();
-}
-
-void (*idle)(void) = default_idle;
-
-/*
- * The idle thread. There's no useful work to be
- * done, so just try to conserve power and have a
- * low exit latency (ie sit in a loop waiting for
- * somebody to say that they'd like to reschedule)
- */
-void cpu_idle(void)
-{
- /* endless idle loop with no priority at all */
- while (1) {
- idle();
- preempt_enable_no_resched();
- schedule();
- preempt_disable();
- }
-}
-
-void machine_restart(char * __unused)
-{
- if (mach_reset)
- mach_reset();
- for (;;);
-}
-
-void machine_halt(void)
-{
- if (mach_halt)
- mach_halt();
- for (;;);
-}
-
-void machine_power_off(void)
-{
- if (mach_power_off)
- mach_power_off();
- for (;;);
-}
-
-void show_regs(struct pt_regs * regs)
-{
- printk(KERN_NOTICE "\n");
- printk(KERN_NOTICE "Format %02x Vector: %04x PC: %08lx Status: %04x %s\n",
- regs->format, regs->vector, regs->pc, regs->sr, print_tainted());
- printk(KERN_NOTICE "ORIG_D0: %08lx D0: %08lx A2: %08lx A1: %08lx\n",
- regs->orig_d0, regs->d0, regs->a2, regs->a1);
- printk(KERN_NOTICE "A0: %08lx D5: %08lx D4: %08lx\n",
- regs->a0, regs->d5, regs->d4);
- printk(KERN_NOTICE "D3: %08lx D2: %08lx D1: %08lx\n",
- regs->d3, regs->d2, regs->d1);
- if (!(regs->sr & PS_S))
- printk(KERN_NOTICE "USP: %08lx\n", rdusp());
-}
-
-/*
- * Create a kernel thread
- */
-int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
-{
- int retval;
- long clone_arg = flags | CLONE_VM;
- mm_segment_t fs;
-
- fs = get_fs();
- set_fs(KERNEL_DS);
-
- __asm__ __volatile__ (
- "movel %%sp, %%d2\n\t"
- "movel %5, %%d1\n\t"
- "movel %1, %%d0\n\t"
- "trap #0\n\t"
- "cmpl %%sp, %%d2\n\t"
- "jeq 1f\n\t"
- "movel %3, %%sp at -\n\t"
- "jsr %4@\n\t"
- "movel %2, %%d0\n\t"
- "trap #0\n"
- "1:\n\t"
- "movel %%d0, %0\n"
- : "=d" (retval)
- : "i" (__NR_clone),
- "i" (__NR_exit),
- "a" (arg),
- "a" (fn),
- "a" (clone_arg)
- : "cc", "%d0", "%d1", "%d2");
-
- set_fs(fs);
- return retval;
-}
-EXPORT_SYMBOL(kernel_thread);
-
-void flush_thread(void)
-{
-#ifdef CONFIG_FPU
- unsigned long zero = 0;
-#endif
-
- current->thread.fs = __USER_DS;
-#ifdef CONFIG_FPU
- if (!FPU_IS_EMU)
- asm volatile (".chip 68k/68881\n\t"
- "frestore %0\n\t"
- ".chip 68k" : : "m" (zero));
-#endif
-}
-
-/*
- * "m68k_fork()".. By the time we get here, the
- * non-volatile registers have also been saved on the
- * stack. We do some ugly pointer stuff here.. (see
- * also copy_thread)
- */
-
-asmlinkage int m68k_fork(struct pt_regs *regs)
-{
- /* fork almost works, enough to trick you into looking elsewhere :-( */
- return(-EINVAL);
-}
-
-asmlinkage int m68k_vfork(struct pt_regs *regs)
-{
- return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(), regs, 0, NULL, NULL);
-}
-
-asmlinkage int m68k_clone(struct pt_regs *regs)
-{
- unsigned long clone_flags;
- unsigned long newsp;
-
- /* syscall2 puts clone_flags in d1 and usp in d2 */
- clone_flags = regs->d1;
- newsp = regs->d2;
- if (!newsp)
- newsp = rdusp();
- return do_fork(clone_flags, newsp, regs, 0, NULL, NULL);
-}
-
-int copy_thread(unsigned long clone_flags,
- unsigned long usp, unsigned long topstk,
- struct task_struct * p, struct pt_regs * regs)
-{
- struct pt_regs * childregs;
- struct switch_stack * childstack, *stack;
- unsigned long *retp;
-
- childregs = (struct pt_regs *) (task_stack_page(p) + THREAD_SIZE) - 1;
-
- *childregs = *regs;
- childregs->d0 = 0;
-
- retp = ((unsigned long *) regs);
- stack = ((struct switch_stack *) retp) - 1;
-
- childstack = ((struct switch_stack *) childregs) - 1;
- *childstack = *stack;
- childstack->retpc = (unsigned long)ret_from_fork;
-
- p->thread.usp = usp;
- p->thread.ksp = (unsigned long)childstack;
-
- if (clone_flags & CLONE_SETTLS)
- task_thread_info(p)->tp_value = regs->d5;
-
- /*
- * Must save the current SFC/DFC value, NOT the value when
- * the parent was last descheduled - RGH 10-08-96
- */
- p->thread.fs = get_fs().seg;
-
-#ifdef CONFIG_FPU
- if (!FPU_IS_EMU) {
- /* Copy the current fpu state */
- asm volatile ("fsave %0" : : "m" (p->thread.fpstate[0]) : "memory");
-
- if (p->thread.fpstate[0])
- asm volatile ("fmovemx %/fp0-%/fp7,%0\n\t"
- "fmoveml %/fpiar/%/fpcr/%/fpsr,%1"
- : : "m" (p->thread.fp[0]), "m" (p->thread.fpcntl[0])
- : "memory");
- /* Restore the state in case the fpu was busy */
- asm volatile ("frestore %0" : : "m" (p->thread.fpstate[0]));
- }
-#endif
-
- return 0;
-}
-
-/* Fill in the fpu structure for a core dump. */
-
-int dump_fpu(struct pt_regs *regs, struct user_m68kfp_struct *fpu)
-{
-#ifdef CONFIG_FPU
- char fpustate[216];
-
- if (FPU_IS_EMU) {
- int i;
-
- memcpy(fpu->fpcntl, current->thread.fpcntl, 12);
- memcpy(fpu->fpregs, current->thread.fp, 96);
- /* Convert internal fpu reg representation
- * into long double format
- */
- for (i = 0; i < 24; i += 3)
- fpu->fpregs[i] = ((fpu->fpregs[i] & 0xffff0000) << 15) |
- ((fpu->fpregs[i] & 0x0000ffff) << 16);
- return 1;
- }
-
- /* First dump the fpu context to avoid protocol violation. */
- asm volatile ("fsave %0" :: "m" (fpustate[0]) : "memory");
- if (!fpustate[0])
- return 0;
-
- asm volatile ("fmovem %/fpiar/%/fpcr/%/fpsr,%0"
- :: "m" (fpu->fpcntl[0])
- : "memory");
- asm volatile ("fmovemx %/fp0-%/fp7,%0"
- :: "m" (fpu->fpregs[0])
- : "memory");
-#endif
- return 1;
-}
-EXPORT_SYMBOL(dump_fpu);
-
-/*
- * Generic dumping code. Used for panic and debug.
- */
-void dump(struct pt_regs *fp)
-{
- unsigned long *sp;
- unsigned char *tp;
- int i;
-
- printk(KERN_EMERG "\nCURRENT PROCESS:\n\n");
- printk(KERN_EMERG "COMM=%s PID=%d\n", current->comm, current->pid);
-
- if (current->mm) {
- printk(KERN_EMERG "TEXT=%08x-%08x DATA=%08x-%08x BSS=%08x-%08x\n",
- (int) current->mm->start_code,
- (int) current->mm->end_code,
- (int) current->mm->start_data,
- (int) current->mm->end_data,
- (int) current->mm->end_data,
- (int) current->mm->brk);
- printk(KERN_EMERG "USER-STACK=%08x KERNEL-STACK=%08x\n\n",
- (int) current->mm->start_stack,
- (int)(((unsigned long) current) + THREAD_SIZE));
- }
-
- printk(KERN_EMERG "PC: %08lx\n", fp->pc);
- printk(KERN_EMERG "SR: %08lx SP: %08lx\n", (long) fp->sr, (long) fp);
- printk(KERN_EMERG "d0: %08lx d1: %08lx d2: %08lx d3: %08lx\n",
- fp->d0, fp->d1, fp->d2, fp->d3);
- printk(KERN_EMERG "d4: %08lx d5: %08lx a0: %08lx a1: %08lx\n",
- fp->d4, fp->d5, fp->a0, fp->a1);
- printk(KERN_EMERG "\nUSP: %08x TRAPFRAME: %p\n",
- (unsigned int) rdusp(), fp);
-
- printk(KERN_EMERG "\nCODE:");
- tp = ((unsigned char *) fp->pc) - 0x20;
- for (sp = (unsigned long *) tp, i = 0; (i < 0x40); i += 4) {
- if ((i % 0x10) == 0)
- printk(KERN_EMERG "%p: ", tp + i);
- printk("%08x ", (int) *sp++);
- }
- printk(KERN_EMERG "\n");
-
- printk(KERN_EMERG "KERNEL STACK:");
- tp = ((unsigned char *) fp) - 0x40;
- for (sp = (unsigned long *) tp, i = 0; (i < 0xc0); i += 4) {
- if ((i % 0x10) == 0)
- printk(KERN_EMERG "%p: ", tp + i);
- printk("%08x ", (int) *sp++);
- }
- printk(KERN_EMERG "\n");
-
- printk(KERN_EMERG "USER STACK:");
- tp = (unsigned char *) (rdusp() - 0x10);
- for (sp = (unsigned long *) tp, i = 0; (i < 0x80); i += 4) {
- if ((i % 0x10) == 0)
- printk(KERN_EMERG "%p: ", tp + i);
- printk("%08x ", (int) *sp++);
- }
- printk(KERN_EMERG "\n");
-}
-
-/*
- * sys_execve() executes a new program.
- */
-asmlinkage int sys_execve(const char *name,
- const char *const *argv,
- const char *const *envp)
-{
- int error;
- char * filename;
- struct pt_regs *regs = (struct pt_regs *) &name;
-
- filename = getname(name);
- error = PTR_ERR(filename);
- if (IS_ERR(filename))
- return error;
- error = do_execve(filename, argv, envp, regs);
- putname(filename);
- return error;
-}
-
-unsigned long get_wchan(struct task_struct *p)
-{
- unsigned long fp, pc;
- unsigned long stack_page;
- int count = 0;
- if (!p || p == current || p->state == TASK_RUNNING)
- return 0;
-
- stack_page = (unsigned long)p;
- fp = ((struct switch_stack *)p->thread.ksp)->a6;
- do {
- if (fp < stack_page+sizeof(struct thread_info) ||
- fp >= THREAD_SIZE-8+stack_page)
- return 0;
- pc = ((unsigned long *)fp)[1];
- if (!in_sched_functions(pc))
- return pc;
- fp = *(unsigned long *) fp;
- } while (count++ < 16);
- return 0;
-}
-
-/*
- * Return saved PC of a blocked thread.
- */
-unsigned long thread_saved_pc(struct task_struct *tsk)
-{
- struct switch_stack *sw = (struct switch_stack *)tsk->thread.ksp;
-
- /* Check whether the thread is blocked in resume() */
- if (in_sched_functions(sw->retpc))
- return ((unsigned long *)sw->a6)[1];
- else
- return sw->retpc;
-}
-
--
1.7.0.4
Geert Uytterhoeven
2012-02-19 10:18:18 UTC
Permalink
Post by gerg
The MMU and non-MMU varients of the m68k arch process.c code are pretty
much the same. Only a few minor details differ between the two. The
majority of the difference is to deal with having or wanting hardware FPU
support. So merge them back into a single process.c file.
Signed-off-by: Greg Ungerer <gerg at uclinux.org>
Acked-by: Geert Uytterhoeven <geert at linux-m68k.org>

Gr{oetje,eeting}s,

? ? ? ? ? ? ? ? ? ? ? ? Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
? ? ? ? ? ? ? ? ? ? ? ? ? ?? ?? -- Linus Torvalds
Geert Uytterhoeven
2012-02-19 10:17:08 UTC
Permalink
Post by gerg
The classic m68k code has always supported an FPU (although it may have
been a software emulated one). The non-MMU m68k code has never supported FPU
hardware. To help in merging common code create a configation setting that
signifies if we are builing in FPU support or not.
This switch, CONFIG_FPU, is set as per the current use cases. So it is
always enabled if CONFIG_MMU is set, and disabled otherwise. With a little
extra code it will be possible to disable it on the classic m68k platforms
as well, and to enable it on non-MMU platforms that do have hardware FPU.
Signed-off-by: Greg Ungerer <gerg at uclinux.org>
Acked-by: Geert Uytterhoeven <geert at linux-m68k.org>

Gr{oetje,eeting}s,

? ? ? ? ? ? ? ? ? ? ? ? Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
? ? ? ? ? ? ? ? ? ? ? ? ? ?? ?? -- Linus Torvalds
Greg Ungerer
2012-02-21 05:56:30 UTC
Permalink
Hi Geert,
Post by gerg
The classic m68k code has always supported an FPU (although it may have
been a software emulated one). The non-MMU m68k code has never supported FPU
hardware. To help in merging common code create a configation setting that
signifies if we are builing in FPU support or not.
This switch, CONFIG_FPU, is set as per the current use cases. So it is
always enabled if CONFIG_MMU is set, and disabled otherwise. With a little
extra code it will be possible to disable it on the classic m68k platforms
as well, and to enable it on non-MMU platforms that do have hardware FPU.
Signed-off-by: Greg Ungerer<gerg at uclinux.org>
Acked-by: Geert Uytterhoeven<geert at linux-m68k.org>
Thanks!

Regards
Greg


------------------------------------------------------------------------
Greg Ungerer -- Principal Engineer EMAIL: gerg at snapgear.com
SnapGear Group, McAfee PHONE: +61 7 3435 2888
8 Gardner Close FAX: +61 7 3217 5323
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