MIPS: Correct MIPS I FP sigcontext layout

Complement commit 80cbfad79096 ("MIPS: Correct MIPS I FP context
layout") and correct the way Floating Point General registers are stored
in a signal context with MIPS I hardware.

Use the S.D and L.D assembly macros to have pairs of SWC1 instructions
and pairs of LWC1 instructions produced, respectively, in an arrangement
which makes the memory representation of floating-point data passed
compatible with that used by hardware SDC1 and LDC1 instructions, where
available, regardless of the hardware endianness used.  This matches the
layout used by r4k_fpu.S, ensuring run-time compatibility for MIPS I
software across all o32 hardware platforms.

Define an EX2 macro to handle exceptions from both hardware instructions
implicitly produced from S.D and L.D assembly macros.

Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14477/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/kernel/r2300_fpu.S b/arch/mips/kernel/r2300_fpu.S
index 70ca637..918f2f6 100644 (file)
--- a/arch/mips/kernel/r2300_fpu.S
+++ b/arch/mips/kernel/r2300_fpu.S
@@ -24,6 +24,13 @@
        PTR     9b,fault;                                       \
        .previous
 
+#define EX2(a,b)                                               \
+9:     a,##b;                                                  \
+       .section __ex_table,"a";                                \
+       PTR     9b,bad_stack;                                   \
+       PTR     9b+4,bad_stack;                                 \
+       .previous
+
        .set    noreorder
        .set    mips1
 
@@ -40,38 +47,22 @@ LEAF(_save_fp_context)
        SET_HARDFLOAT
        li      v0, 0                                   # assume success
        cfc1    t1, fcr31
-       EX(swc1 $f0, 0(a0))
-       EX(swc1 $f1, 8(a0))
-       EX(swc1 $f2, 16(a0))
-       EX(swc1 $f3, 24(a0))
-       EX(swc1 $f4, 32(a0))
-       EX(swc1 $f5, 40(a0))
-       EX(swc1 $f6, 48(a0))
-       EX(swc1 $f7, 56(a0))
-       EX(swc1 $f8, 64(a0))
-       EX(swc1 $f9, 72(a0))
-       EX(swc1 $f10, 80(a0))
-       EX(swc1 $f11, 88(a0))
-       EX(swc1 $f12, 96(a0))
-       EX(swc1 $f13, 104(a0))
-       EX(swc1 $f14, 112(a0))
-       EX(swc1 $f15, 120(a0))
-       EX(swc1 $f16, 128(a0))
-       EX(swc1 $f17, 136(a0))
-       EX(swc1 $f18, 144(a0))
-       EX(swc1 $f19, 152(a0))
-       EX(swc1 $f20, 160(a0))
-       EX(swc1 $f21, 168(a0))
-       EX(swc1 $f22, 176(a0))
-       EX(swc1 $f23, 184(a0))
-       EX(swc1 $f24, 192(a0))
-       EX(swc1 $f25, 200(a0))
-       EX(swc1 $f26, 208(a0))
-       EX(swc1 $f27, 216(a0))
-       EX(swc1 $f28, 224(a0))
-       EX(swc1 $f29, 232(a0))
-       EX(swc1 $f30, 240(a0))
-       EX(swc1 $f31, 248(a0))
+       EX2(s.d $f0, 0(a0))
+       EX2(s.d $f2, 16(a0))
+       EX2(s.d $f4, 32(a0))
+       EX2(s.d $f6, 48(a0))
+       EX2(s.d $f8, 64(a0))
+       EX2(s.d $f10, 80(a0))
+       EX2(s.d $f12, 96(a0))
+       EX2(s.d $f14, 112(a0))
+       EX2(s.d $f16, 128(a0))
+       EX2(s.d $f18, 144(a0))
+       EX2(s.d $f20, 160(a0))
+       EX2(s.d $f22, 176(a0))
+       EX2(s.d $f24, 192(a0))
+       EX2(s.d $f26, 208(a0))
+       EX2(s.d $f28, 224(a0))
+       EX2(s.d $f30, 240(a0))
        jr      ra
         EX(sw  t1, (a1))
        .set    pop
@@ -90,38 +81,22 @@ LEAF(_restore_fp_context)
        SET_HARDFLOAT
        li      v0, 0                                   # assume success
        EX(lw t0, (a1))
-       EX(lwc1 $f0, 0(a0))
-       EX(lwc1 $f1, 8(a0))
-       EX(lwc1 $f2, 16(a0))
-       EX(lwc1 $f3, 24(a0))
-       EX(lwc1 $f4, 32(a0))
-       EX(lwc1 $f5, 40(a0))
-       EX(lwc1 $f6, 48(a0))
-       EX(lwc1 $f7, 56(a0))
-       EX(lwc1 $f8, 64(a0))
-       EX(lwc1 $f9, 72(a0))
-       EX(lwc1 $f10, 80(a0))
-       EX(lwc1 $f11, 88(a0))
-       EX(lwc1 $f12, 96(a0))
-       EX(lwc1 $f13, 104(a0))
-       EX(lwc1 $f14, 112(a0))
-       EX(lwc1 $f15, 120(a0))
-       EX(lwc1 $f16, 128(a0))
-       EX(lwc1 $f17, 136(a0))
-       EX(lwc1 $f18, 144(a0))
-       EX(lwc1 $f19, 152(a0))
-       EX(lwc1 $f20, 160(a0))
-       EX(lwc1 $f21, 168(a0))
-       EX(lwc1 $f22, 176(a0))
-       EX(lwc1 $f23, 184(a0))
-       EX(lwc1 $f24, 192(a0))
-       EX(lwc1 $f25, 200(a0))
-       EX(lwc1 $f26, 208(a0))
-       EX(lwc1 $f27, 216(a0))
-       EX(lwc1 $f28, 224(a0))
-       EX(lwc1 $f29, 232(a0))
-       EX(lwc1 $f30, 240(a0))
-       EX(lwc1 $f31, 248(a0))
+       EX2(l.d $f0, 0(a0))
+       EX2(l.d $f2, 16(a0))
+       EX2(l.d $f4, 32(a0))
+       EX2(l.d $f6, 48(a0))
+       EX2(l.d $f8, 64(a0))
+       EX2(l.d $f10, 80(a0))
+       EX2(l.d $f12, 96(a0))
+       EX2(l.d $f14, 112(a0))
+       EX2(l.d $f16, 128(a0))
+       EX2(l.d $f18, 144(a0))
+       EX2(l.d $f20, 160(a0))
+       EX2(l.d $f22, 176(a0))
+       EX2(l.d $f24, 192(a0))
+       EX2(l.d $f26, 208(a0))
+       EX2(l.d $f28, 224(a0))
+       EX2(l.d $f30, 240(a0))
        jr      ra
         ctc1   t0, fcr31
        .set    pop