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Diffstat (limited to 'arch/sh/kernel/cpu/sh4/fpu.c')
-rw-r--r--arch/sh/kernel/cpu/sh4/fpu.c335
1 files changed, 335 insertions, 0 deletions
diff --git a/arch/sh/kernel/cpu/sh4/fpu.c b/arch/sh/kernel/cpu/sh4/fpu.c
new file mode 100644
index 000000000000..f486c07e10e2
--- /dev/null
+++ b/arch/sh/kernel/cpu/sh4/fpu.c
@@ -0,0 +1,335 @@
+/* $Id: fpu.c,v 1.4 2004/01/13 05:52:11 kkojima Exp $
+ *
+ * linux/arch/sh/kernel/fpu.c
+ *
+ * Save/restore floating point context for signal handlers.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 1999, 2000 Kaz Kojima & Niibe Yutaka
+ *
+ * FIXME! These routines can be optimized in big endian case.
+ */
+
+#include <linux/sched.h>
+#include <linux/signal.h>
+#include <asm/processor.h>
+#include <asm/io.h>
+
+/* The PR (precision) bit in the FP Status Register must be clear when
+ * an frchg instruction is executed, otherwise the instruction is undefined.
+ * Executing frchg with PR set causes a trap on some SH4 implementations.
+ */
+
+#define FPSCR_RCHG 0x00000000
+
+
+/*
+ * Save FPU registers onto task structure.
+ * Assume called with FPU enabled (SR.FD=0).
+ */
+void
+save_fpu(struct task_struct *tsk, struct pt_regs *regs)
+{
+ unsigned long dummy;
+
+ clear_tsk_thread_flag(tsk, TIF_USEDFPU);
+ enable_fpu();
+ asm volatile("sts.l fpul, @-%0\n\t"
+ "sts.l fpscr, @-%0\n\t"
+ "lds %2, fpscr\n\t"
+ "frchg\n\t"
+ "fmov.s fr15, @-%0\n\t"
+ "fmov.s fr14, @-%0\n\t"
+ "fmov.s fr13, @-%0\n\t"
+ "fmov.s fr12, @-%0\n\t"
+ "fmov.s fr11, @-%0\n\t"
+ "fmov.s fr10, @-%0\n\t"
+ "fmov.s fr9, @-%0\n\t"
+ "fmov.s fr8, @-%0\n\t"
+ "fmov.s fr7, @-%0\n\t"
+ "fmov.s fr6, @-%0\n\t"
+ "fmov.s fr5, @-%0\n\t"
+ "fmov.s fr4, @-%0\n\t"
+ "fmov.s fr3, @-%0\n\t"
+ "fmov.s fr2, @-%0\n\t"
+ "fmov.s fr1, @-%0\n\t"
+ "fmov.s fr0, @-%0\n\t"
+ "frchg\n\t"
+ "fmov.s fr15, @-%0\n\t"
+ "fmov.s fr14, @-%0\n\t"
+ "fmov.s fr13, @-%0\n\t"
+ "fmov.s fr12, @-%0\n\t"
+ "fmov.s fr11, @-%0\n\t"
+ "fmov.s fr10, @-%0\n\t"
+ "fmov.s fr9, @-%0\n\t"
+ "fmov.s fr8, @-%0\n\t"
+ "fmov.s fr7, @-%0\n\t"
+ "fmov.s fr6, @-%0\n\t"
+ "fmov.s fr5, @-%0\n\t"
+ "fmov.s fr4, @-%0\n\t"
+ "fmov.s fr3, @-%0\n\t"
+ "fmov.s fr2, @-%0\n\t"
+ "fmov.s fr1, @-%0\n\t"
+ "fmov.s fr0, @-%0\n\t"
+ "lds %3, fpscr\n\t"
+ : "=r" (dummy)
+ : "0" ((char *)(&tsk->thread.fpu.hard.status)),
+ "r" (FPSCR_RCHG),
+ "r" (FPSCR_INIT)
+ : "memory");
+
+ disable_fpu();
+ release_fpu(regs);
+}
+
+static void
+restore_fpu(struct task_struct *tsk)
+{
+ unsigned long dummy;
+
+ enable_fpu();
+ asm volatile("lds %2, fpscr\n\t"
+ "fmov.s @%0+, fr0\n\t"
+ "fmov.s @%0+, fr1\n\t"
+ "fmov.s @%0+, fr2\n\t"
+ "fmov.s @%0+, fr3\n\t"
+ "fmov.s @%0+, fr4\n\t"
+ "fmov.s @%0+, fr5\n\t"
+ "fmov.s @%0+, fr6\n\t"
+ "fmov.s @%0+, fr7\n\t"
+ "fmov.s @%0+, fr8\n\t"
+ "fmov.s @%0+, fr9\n\t"
+ "fmov.s @%0+, fr10\n\t"
+ "fmov.s @%0+, fr11\n\t"
+ "fmov.s @%0+, fr12\n\t"
+ "fmov.s @%0+, fr13\n\t"
+ "fmov.s @%0+, fr14\n\t"
+ "fmov.s @%0+, fr15\n\t"
+ "frchg\n\t"
+ "fmov.s @%0+, fr0\n\t"
+ "fmov.s @%0+, fr1\n\t"
+ "fmov.s @%0+, fr2\n\t"
+ "fmov.s @%0+, fr3\n\t"
+ "fmov.s @%0+, fr4\n\t"
+ "fmov.s @%0+, fr5\n\t"
+ "fmov.s @%0+, fr6\n\t"
+ "fmov.s @%0+, fr7\n\t"
+ "fmov.s @%0+, fr8\n\t"
+ "fmov.s @%0+, fr9\n\t"
+ "fmov.s @%0+, fr10\n\t"
+ "fmov.s @%0+, fr11\n\t"
+ "fmov.s @%0+, fr12\n\t"
+ "fmov.s @%0+, fr13\n\t"
+ "fmov.s @%0+, fr14\n\t"
+ "fmov.s @%0+, fr15\n\t"
+ "frchg\n\t"
+ "lds.l @%0+, fpscr\n\t"
+ "lds.l @%0+, fpul\n\t"
+ : "=r" (dummy)
+ : "0" (&tsk->thread.fpu), "r" (FPSCR_RCHG)
+ : "memory");
+ disable_fpu();
+}
+
+/*
+ * Load the FPU with signalling NANS. This bit pattern we're using
+ * has the property that no matter wether considered as single or as
+ * double precission represents signaling NANS.
+ */
+
+static void
+fpu_init(void)
+{
+ enable_fpu();
+ asm volatile("lds %0, fpul\n\t"
+ "lds %1, fpscr\n\t"
+ "fsts fpul, fr0\n\t"
+ "fsts fpul, fr1\n\t"
+ "fsts fpul, fr2\n\t"
+ "fsts fpul, fr3\n\t"
+ "fsts fpul, fr4\n\t"
+ "fsts fpul, fr5\n\t"
+ "fsts fpul, fr6\n\t"
+ "fsts fpul, fr7\n\t"
+ "fsts fpul, fr8\n\t"
+ "fsts fpul, fr9\n\t"
+ "fsts fpul, fr10\n\t"
+ "fsts fpul, fr11\n\t"
+ "fsts fpul, fr12\n\t"
+ "fsts fpul, fr13\n\t"
+ "fsts fpul, fr14\n\t"
+ "fsts fpul, fr15\n\t"
+ "frchg\n\t"
+ "fsts fpul, fr0\n\t"
+ "fsts fpul, fr1\n\t"
+ "fsts fpul, fr2\n\t"
+ "fsts fpul, fr3\n\t"
+ "fsts fpul, fr4\n\t"
+ "fsts fpul, fr5\n\t"
+ "fsts fpul, fr6\n\t"
+ "fsts fpul, fr7\n\t"
+ "fsts fpul, fr8\n\t"
+ "fsts fpul, fr9\n\t"
+ "fsts fpul, fr10\n\t"
+ "fsts fpul, fr11\n\t"
+ "fsts fpul, fr12\n\t"
+ "fsts fpul, fr13\n\t"
+ "fsts fpul, fr14\n\t"
+ "fsts fpul, fr15\n\t"
+ "frchg\n\t"
+ "lds %2, fpscr\n\t"
+ : /* no output */
+ : "r" (0), "r" (FPSCR_RCHG), "r" (FPSCR_INIT));
+ disable_fpu();
+}
+
+/**
+ * denormal_to_double - Given denormalized float number,
+ * store double float
+ *
+ * @fpu: Pointer to sh_fpu_hard structure
+ * @n: Index to FP register
+ */
+static void
+denormal_to_double (struct sh_fpu_hard_struct *fpu, int n)
+{
+ unsigned long du, dl;
+ unsigned long x = fpu->fpul;
+ int exp = 1023 - 126;
+
+ if (x != 0 && (x & 0x7f800000) == 0) {
+ du = (x & 0x80000000);
+ while ((x & 0x00800000) == 0) {
+ x <<= 1;
+ exp--;
+ }
+ x &= 0x007fffff;
+ du |= (exp << 20) | (x >> 3);
+ dl = x << 29;
+
+ fpu->fp_regs[n] = du;
+ fpu->fp_regs[n+1] = dl;
+ }
+}
+
+/**
+ * ieee_fpe_handler - Handle denormalized number exception
+ *
+ * @regs: Pointer to register structure
+ *
+ * Returns 1 when it's handled (should not cause exception).
+ */
+static int
+ieee_fpe_handler (struct pt_regs *regs)
+{
+ unsigned short insn = *(unsigned short *) regs->pc;
+ unsigned short finsn;
+ unsigned long nextpc;
+ int nib[4] = {
+ (insn >> 12) & 0xf,
+ (insn >> 8) & 0xf,
+ (insn >> 4) & 0xf,
+ insn & 0xf};
+
+ if (nib[0] == 0xb ||
+ (nib[0] == 0x4 && nib[2] == 0x0 && nib[3] == 0xb)) /* bsr & jsr */
+ regs->pr = regs->pc + 4;
+
+ if (nib[0] == 0xa || nib[0] == 0xb) { /* bra & bsr */
+ nextpc = regs->pc + 4 + ((short) ((insn & 0xfff) << 4) >> 3);
+ finsn = *(unsigned short *) (regs->pc + 2);
+ } else if (nib[0] == 0x8 && nib[1] == 0xd) { /* bt/s */
+ if (regs->sr & 1)
+ nextpc = regs->pc + 4 + ((char) (insn & 0xff) << 1);
+ else
+ nextpc = regs->pc + 4;
+ finsn = *(unsigned short *) (regs->pc + 2);
+ } else if (nib[0] == 0x8 && nib[1] == 0xf) { /* bf/s */
+ if (regs->sr & 1)
+ nextpc = regs->pc + 4;
+ else
+ nextpc = regs->pc + 4 + ((char) (insn & 0xff) << 1);
+ finsn = *(unsigned short *) (regs->pc + 2);
+ } else if (nib[0] == 0x4 && nib[3] == 0xb &&
+ (nib[2] == 0x0 || nib[2] == 0x2)) { /* jmp & jsr */
+ nextpc = regs->regs[nib[1]];
+ finsn = *(unsigned short *) (regs->pc + 2);
+ } else if (nib[0] == 0x0 && nib[3] == 0x3 &&
+ (nib[2] == 0x0 || nib[2] == 0x2)) { /* braf & bsrf */
+ nextpc = regs->pc + 4 + regs->regs[nib[1]];
+ finsn = *(unsigned short *) (regs->pc + 2);
+ } else if (insn == 0x000b) { /* rts */
+ nextpc = regs->pr;
+ finsn = *(unsigned short *) (regs->pc + 2);
+ } else {
+ nextpc = regs->pc + 2;
+ finsn = insn;
+ }
+
+ if ((finsn & 0xf1ff) == 0xf0ad) { /* fcnvsd */
+ struct task_struct *tsk = current;
+
+ save_fpu(tsk, regs);
+ if ((tsk->thread.fpu.hard.fpscr & (1 << 17))) {
+ /* FPU error */
+ denormal_to_double (&tsk->thread.fpu.hard,
+ (finsn >> 8) & 0xf);
+ tsk->thread.fpu.hard.fpscr &=
+ ~(FPSCR_CAUSE_MASK | FPSCR_FLAG_MASK);
+ grab_fpu(regs);
+ restore_fpu(tsk);
+ set_tsk_thread_flag(tsk, TIF_USEDFPU);
+ } else {
+ tsk->thread.trap_no = 11;
+ tsk->thread.error_code = 0;
+ force_sig(SIGFPE, tsk);
+ }
+
+ regs->pc = nextpc;
+ return 1;
+ }
+
+ return 0;
+}
+
+asmlinkage void
+do_fpu_error(unsigned long r4, unsigned long r5, unsigned long r6, unsigned long r7,
+ struct pt_regs regs)
+{
+ struct task_struct *tsk = current;
+
+ if (ieee_fpe_handler (&regs))
+ return;
+
+ regs.pc += 2;
+ save_fpu(tsk, &regs);
+ tsk->thread.trap_no = 11;
+ tsk->thread.error_code = 0;
+ force_sig(SIGFPE, tsk);
+}
+
+asmlinkage void
+do_fpu_state_restore(unsigned long r4, unsigned long r5, unsigned long r6,
+ unsigned long r7, struct pt_regs regs)
+{
+ struct task_struct *tsk = current;
+
+ grab_fpu(&regs);
+ if (!user_mode(&regs)) {
+ printk(KERN_ERR "BUG: FPU is used in kernel mode.\n");
+ return;
+ }
+
+ if (used_math()) {
+ /* Using the FPU again. */
+ restore_fpu(tsk);
+ } else {
+ /* First time FPU user. */
+ fpu_init();
+ set_used_math();
+ }
+ set_tsk_thread_flag(tsk, TIF_USEDFPU);
+}
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