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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/arm/vfp/vfphw.S
downloadconfigs-2.6.12-rc2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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+/*
+ * linux/arch/arm/vfp/vfphw.S
+ *
+ * Copyright (C) 2004 ARM Limited.
+ * Written by Deep Blue Solutions Limited.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This code is called from the kernel's undefined instruction trap.
+ * r9 holds the return address for successful handling.
+ * lr holds the return address for unrecognised instructions.
+ * r10 points at the start of the private FP workspace in the thread structure
+ * sp points to a struct pt_regs (as defined in include/asm/proc/ptrace.h)
+ */
+#include <asm/thread_info.h>
+#include <asm/vfpmacros.h>
+#include "../kernel/entry-header.S"
+
+ .macro DBGSTR, str
+#ifdef DEBUG
+ stmfd sp!, {r0-r3, ip, lr}
+ add r0, pc, #4
+ bl printk
+ b 1f
+ .asciz "<7>VFP: \str\n"
+ .balign 4
+1: ldmfd sp!, {r0-r3, ip, lr}
+#endif
+ .endm
+
+ .macro DBGSTR1, str, arg
+#ifdef DEBUG
+ stmfd sp!, {r0-r3, ip, lr}
+ mov r1, \arg
+ add r0, pc, #4
+ bl printk
+ b 1f
+ .asciz "<7>VFP: \str\n"
+ .balign 4
+1: ldmfd sp!, {r0-r3, ip, lr}
+#endif
+ .endm
+
+ .macro DBGSTR3, str, arg1, arg2, arg3
+#ifdef DEBUG
+ stmfd sp!, {r0-r3, ip, lr}
+ mov r3, \arg3
+ mov r2, \arg2
+ mov r1, \arg1
+ add r0, pc, #4
+ bl printk
+ b 1f
+ .asciz "<7>VFP: \str\n"
+ .balign 4
+1: ldmfd sp!, {r0-r3, ip, lr}
+#endif
+ .endm
+
+
+@ VFP hardware support entry point.
+@
+@ r0 = faulted instruction
+@ r2 = faulted PC+4
+@ r9 = successful return
+@ r10 = vfp_state union
+@ lr = failure return
+
+ .globl vfp_support_entry
+vfp_support_entry:
+ DBGSTR3 "instr %08x pc %08x state %p", r0, r2, r10
+
+ VFPFMRX r1, FPEXC @ Is the VFP enabled?
+ DBGSTR1 "fpexc %08x", r1
+ tst r1, #FPEXC_ENABLE
+ bne look_for_VFP_exceptions @ VFP is already enabled
+
+ DBGSTR1 "enable %x", r10
+ ldr r3, last_VFP_context_address
+ orr r1, r1, #FPEXC_ENABLE @ user FPEXC has the enable bit set
+ ldr r4, [r3] @ last_VFP_context pointer
+ bic r5, r1, #FPEXC_EXCEPTION @ make sure exceptions are disabled
+ cmp r4, r10
+ beq check_for_exception @ we are returning to the same
+ @ process, so the registers are
+ @ still there. In this case, we do
+ @ not want to drop a pending exception.
+
+ VFPFMXR FPEXC, r5 @ enable VFP, disable any pending
+ @ exceptions, so we can get at the
+ @ rest of it
+
+ @ Save out the current registers to the old thread state
+
+ DBGSTR1 "save old state %p", r4
+ cmp r4, #0
+ beq no_old_VFP_process
+ VFPFMRX r5, FPSCR @ current status
+ VFPFMRX r6, FPINST @ FPINST (always there, rev0 onwards)
+ tst r1, #FPEXC_FPV2 @ is there an FPINST2 to read?
+ VFPFMRX r8, FPINST2, NE @ FPINST2 if needed - avoids reading
+ @ nonexistant reg on rev0
+ VFPFSTMIA r4 @ save the working registers
+ add r4, r4, #8*16+4
+ stmia r4, {r1, r5, r6, r8} @ save FPEXC, FPSCR, FPINST, FPINST2
+ @ and point r4 at the word at the
+ @ start of the register dump
+
+no_old_VFP_process:
+ DBGSTR1 "load state %p", r10
+ str r10, [r3] @ update the last_VFP_context pointer
+ @ Load the saved state back into the VFP
+ add r4, r10, #8*16+4
+ ldmia r4, {r1, r5, r6, r8} @ load FPEXC, FPSCR, FPINST, FPINST2
+ VFPFLDMIA r10 @ reload the working registers while
+ @ FPEXC is in a safe state
+ tst r1, #FPEXC_FPV2 @ is there an FPINST2 to write?
+ VFPFMXR FPINST2, r8, NE @ FPINST2 if needed - avoids writing
+ @ nonexistant reg on rev0
+ VFPFMXR FPINST, r6
+ VFPFMXR FPSCR, r5 @ restore status
+
+check_for_exception:
+ tst r1, #FPEXC_EXCEPTION
+ bne process_exception @ might as well handle the pending
+ @ exception before retrying branch
+ @ out before setting an FPEXC that
+ @ stops us reading stuff
+ VFPFMXR FPEXC, r1 @ restore FPEXC last
+ sub r2, r2, #4
+ str r2, [sp, #S_PC] @ retry the instruction
+ mov pc, r9 @ we think we have handled things
+
+
+look_for_VFP_exceptions:
+ tst r1, #FPEXC_EXCEPTION
+ bne process_exception
+ VFPFMRX r5, FPSCR
+ tst r5, #FPSCR_IXE @ IXE doesn't set FPEXC_EXCEPTION !
+ bne process_exception
+
+ @ Fall into hand on to next handler - appropriate coproc instr
+ @ not recognised by VFP
+
+ DBGSTR "not VFP"
+ mov pc, lr
+
+process_exception:
+ DBGSTR "bounce"
+ sub r2, r2, #4
+ str r2, [sp, #S_PC] @ retry the instruction on exit from
+ @ the imprecise exception handling in
+ @ the support code
+ mov r2, sp @ nothing stacked - regdump is at TOS
+ mov lr, r9 @ setup for a return to the user code.
+
+ @ Now call the C code to package up the bounce to the support code
+ @ r0 holds the trigger instruction
+ @ r1 holds the FPEXC value
+ @ r2 pointer to register dump
+ b VFP9_bounce @ we have handled this - the support
+ @ code will raise an exception if
+ @ required. If not, the user code will
+ @ retry the faulted instruction
+
+last_VFP_context_address:
+ .word last_VFP_context
+
+ .globl vfp_get_float
+vfp_get_float:
+ add pc, pc, r0, lsl #3
+ mov r0, r0
+ .irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
+ mrc p10, 0, r0, c\dr, c0, 0 @ fmrs r0, s0
+ mov pc, lr
+ mrc p10, 0, r0, c\dr, c0, 4 @ fmrs r0, s1
+ mov pc, lr
+ .endr
+
+ .globl vfp_put_float
+vfp_put_float:
+ add pc, pc, r0, lsl #3
+ mov r0, r0
+ .irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
+ mcr p10, 0, r1, c\dr, c0, 0 @ fmsr r0, s0
+ mov pc, lr
+ mcr p10, 0, r1, c\dr, c0, 4 @ fmsr r0, s1
+ mov pc, lr
+ .endr
+
+ .globl vfp_get_double
+vfp_get_double:
+ mov r0, r0, lsr #1
+ add pc, pc, r0, lsl #3
+ mov r0, r0
+ .irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
+ mrrc p10, 1, r0, r1, c\dr @ fmrrd r0, r1, d\dr
+ mov pc, lr
+ .endr
+
+ @ virtual register 16 for compare with zero
+ mov r0, #0
+ mov r1, #0
+ mov pc, lr
+
+ .globl vfp_put_double
+vfp_put_double:
+ mov r0, r0, lsr #1
+ add pc, pc, r0, lsl #3
+ mov r0, r0
+ .irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
+ mcrr p10, 1, r1, r2, c\dr @ fmrrd r1, r2, d\dr
+ mov pc, lr
+ .endr