kext: even more perf improvements

Turns out the undef handler path is quite hot, as only one thread per core can have VFP enabled at a time.

k11_extension/Makefile

@@ -25,7 +25,8 @@ INCLUDES	:=	include include/svc
 #---------------------------------------------------------------------------------
 # options for code generation
 #---------------------------------------------------------------------------------
-ARCH	:=	-march=armv6k -mtune=mpcore -mfloat-abi=hard -mtp=soft
+# -mgeneral-regs-only so that the C code is guaranteed not to use FPU regs
+ARCH	:=	-march=armv6k -mtune=mpcore -mfloat-abi=hard -mtp=soft -mgeneral-regs-only
 DEFINES :=	-DARM11 -D_3DS
 
 FALSEPOSITIVES := -Wno-array-bounds -Wno-stringop-overflow -Wno-stringop-overread

k11_extension/source/fatalExceptionHandlers.s

@@ -24,23 +24,6 @@
 
 .fpu vfp
 
-.macro TEST_IF_MODE_AND_ARM_INST_OR_JUMP lbl, mode
-    cpsid aif
-    mrs sp, spsr
-    tst sp, #0x20
-    bne \lbl
-    and sp, #0x1f                @ get previous processor mode
-    cmp sp, #\mode
-    bne \lbl
-
-    sub sp, lr, #4
-    mcr p15, 0, sp, c7, c8, 0    @ VA to PA translation with privileged read permission check
-    mrc p15, 0, sp, c7, c4, 0    @ read PA register
-    tst sp, #1                   @ failure bit
-    bne \lbl
-.endm
-
-
 .macro GEN_USUAL_HANDLER name, index, pos
     \name\()Handler:
         ldr sp, =exceptionStackTop
@@ -180,14 +163,20 @@ _commonHandler:
 .type   FIQHandler, %function
 GEN_USUAL_HANDLER FIQ, 0, 28
 
+.align  5
 .global undefinedInstructionHandler
 .type   undefinedInstructionHandler, %function
 undefinedInstructionHandler:
-    TEST_IF_MODE_AND_ARM_INST_OR_JUMP _undefinedInstructionNormalHandler, 0x10
+    @ Most of the time, we're here to re-enable the FPU (over and over again)
+    mrs sp, spsr
+    @ We can assume bit4 is always set in SPSR. Test if if it's not thumb and if it's usermode
+    tst sp, #0x2F
+    bne _undefinedInstructionNormalHandler
 
-    ldr sp, [lr, #-4]   @ test if it's an VFP instruction that was aborted
+    @ Test if it's an VFP instruction that was aborted
+    ldr sp, [lr, #-4]
     lsl sp, #4
-    sub sp, #0xc0000000
+    sub sp, #0xC0000000
     cmp sp, #0x30000000
     bcs _undefinedInstructionNormalHandler
     fmrx sp, fpexc
@@ -212,8 +201,6 @@ undefinedInstructionHandler:
 .global prefetchAbortHandler
 .type   prefetchAbortHandler, %function
 prefetchAbortHandler:
-    TEST_IF_MODE_AND_ARM_INST_OR_JUMP _prefetchAbortNormalHandler, 0x13
-
     ldr sp, =(Break + 3*4 + 4)
     cmp lr, sp
     bne _prefetchAbortNormalHandler

k11_extension/source/svcHandler.s

@@ -24,7 +24,7 @@
 
 .text
 .arm
-.balign 4
+.align 5
 
 .global svcHandler
 .type   svcHandler, %function
@@ -45,14 +45,6 @@ svcHandler:
 
     ldr r8, =alteredSvcTable
     ldr r8, [r8, r9,lsl#2]
-    /*@ sp = page end - 0x110
-    add r0, sp, #0x110       @ page end
-    bl svcHook
-    cpsid i
-    mov r8, r0
-    ldmfd sp, {r0-r7, r12, lr}
-    */
-
     cmp r8, #0
     beq _fallback            @ invalid svc, or svc 0xff (stop point)