forked from Minki/linux
7eb25ebee8
Directives such as .long and .word do not magically cause the
assembler location counter to become aligned in gas. As a result,
using these directives in code sections can result in misaligned
data words when building a Thumb-2 kernel (CONFIG_THUMB2_KERNEL).
This is a Bad Thing, since the ABI permits the compiler to assume
that fundamental types of word size or above are word- aligned when
accessing them from C. If the data is not really word-aligned,
this can cause impaired performance and stray alignment faults in
some circumstances.
In general, the following rules should be applied when using data
word declaration directives inside code sections:
* .quad and .double:
.align 3
* .long, .word, .single, .float:
.align (or .align 2)
* .short:
No explicit alignment required, since Thumb-2
instructions are always 2 or 4 bytes in size.
immediately after an instruction.
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Dave Martin <dave.martin@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
287 lines
7.3 KiB
ArmAsm
287 lines
7.3 KiB
ArmAsm
/*
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* linux/arch/arm/vfp/vfphw.S
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*
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* Copyright (C) 2004 ARM Limited.
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* Written by Deep Blue Solutions Limited.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This code is called from the kernel's undefined instruction trap.
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* r9 holds the return address for successful handling.
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* lr holds the return address for unrecognised instructions.
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* r10 points at the start of the private FP workspace in the thread structure
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* sp points to a struct pt_regs (as defined in include/asm/proc/ptrace.h)
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*/
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#include <asm/thread_info.h>
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#include <asm/vfpmacros.h>
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#include "../kernel/entry-header.S"
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.macro DBGSTR, str
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#ifdef DEBUG
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stmfd sp!, {r0-r3, ip, lr}
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add r0, pc, #4
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bl printk
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b 1f
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.asciz "<7>VFP: \str\n"
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.balign 4
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1: ldmfd sp!, {r0-r3, ip, lr}
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#endif
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.endm
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.macro DBGSTR1, str, arg
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#ifdef DEBUG
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stmfd sp!, {r0-r3, ip, lr}
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mov r1, \arg
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add r0, pc, #4
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bl printk
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b 1f
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.asciz "<7>VFP: \str\n"
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.balign 4
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1: ldmfd sp!, {r0-r3, ip, lr}
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#endif
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.endm
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.macro DBGSTR3, str, arg1, arg2, arg3
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#ifdef DEBUG
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stmfd sp!, {r0-r3, ip, lr}
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mov r3, \arg3
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mov r2, \arg2
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mov r1, \arg1
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add r0, pc, #4
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bl printk
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b 1f
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.asciz "<7>VFP: \str\n"
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.balign 4
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1: ldmfd sp!, {r0-r3, ip, lr}
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#endif
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.endm
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@ VFP hardware support entry point.
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@
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@ r0 = faulted instruction
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@ r2 = faulted PC+4
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@ r9 = successful return
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@ r10 = vfp_state union
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@ r11 = CPU number
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@ lr = failure return
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ENTRY(vfp_support_entry)
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DBGSTR3 "instr %08x pc %08x state %p", r0, r2, r10
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VFPFMRX r1, FPEXC @ Is the VFP enabled?
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DBGSTR1 "fpexc %08x", r1
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tst r1, #FPEXC_EN
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bne look_for_VFP_exceptions @ VFP is already enabled
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DBGSTR1 "enable %x", r10
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ldr r3, last_VFP_context_address
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orr r1, r1, #FPEXC_EN @ user FPEXC has the enable bit set
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ldr r4, [r3, r11, lsl #2] @ last_VFP_context pointer
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bic r5, r1, #FPEXC_EX @ make sure exceptions are disabled
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cmp r4, r10
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beq check_for_exception @ we are returning to the same
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@ process, so the registers are
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@ still there. In this case, we do
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@ not want to drop a pending exception.
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VFPFMXR FPEXC, r5 @ enable VFP, disable any pending
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@ exceptions, so we can get at the
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@ rest of it
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#ifndef CONFIG_SMP
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@ Save out the current registers to the old thread state
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@ No need for SMP since this is not done lazily
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DBGSTR1 "save old state %p", r4
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cmp r4, #0
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beq no_old_VFP_process
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VFPFSTMIA r4, r5 @ save the working registers
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VFPFMRX r5, FPSCR @ current status
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#ifndef CONFIG_CPU_FEROCEON
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tst r1, #FPEXC_EX @ is there additional state to save?
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beq 1f
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VFPFMRX r6, FPINST @ FPINST (only if FPEXC.EX is set)
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tst r1, #FPEXC_FP2V @ is there an FPINST2 to read?
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beq 1f
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VFPFMRX r8, FPINST2 @ FPINST2 if needed (and present)
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1:
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#endif
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stmia r4, {r1, r5, r6, r8} @ save FPEXC, FPSCR, FPINST, FPINST2
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@ and point r4 at the word at the
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@ start of the register dump
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#endif
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no_old_VFP_process:
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DBGSTR1 "load state %p", r10
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str r10, [r3, r11, lsl #2] @ update the last_VFP_context pointer
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@ Load the saved state back into the VFP
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VFPFLDMIA r10, r5 @ reload the working registers while
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@ FPEXC is in a safe state
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ldmia r10, {r1, r5, r6, r8} @ load FPEXC, FPSCR, FPINST, FPINST2
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#ifndef CONFIG_CPU_FEROCEON
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tst r1, #FPEXC_EX @ is there additional state to restore?
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beq 1f
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VFPFMXR FPINST, r6 @ restore FPINST (only if FPEXC.EX is set)
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tst r1, #FPEXC_FP2V @ is there an FPINST2 to write?
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beq 1f
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VFPFMXR FPINST2, r8 @ FPINST2 if needed (and present)
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1:
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#endif
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VFPFMXR FPSCR, r5 @ restore status
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check_for_exception:
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tst r1, #FPEXC_EX
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bne process_exception @ might as well handle the pending
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@ exception before retrying branch
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@ out before setting an FPEXC that
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@ stops us reading stuff
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VFPFMXR FPEXC, r1 @ restore FPEXC last
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sub r2, r2, #4
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str r2, [sp, #S_PC] @ retry the instruction
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#ifdef CONFIG_PREEMPT
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get_thread_info r10
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ldr r4, [r10, #TI_PREEMPT] @ get preempt count
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sub r11, r4, #1 @ decrement it
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str r11, [r10, #TI_PREEMPT]
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#endif
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mov pc, r9 @ we think we have handled things
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look_for_VFP_exceptions:
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@ Check for synchronous or asynchronous exception
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tst r1, #FPEXC_EX | FPEXC_DEX
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bne process_exception
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@ On some implementations of the VFP subarch 1, setting FPSCR.IXE
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@ causes all the CDP instructions to be bounced synchronously without
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@ setting the FPEXC.EX bit
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VFPFMRX r5, FPSCR
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tst r5, #FPSCR_IXE
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bne process_exception
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@ Fall into hand on to next handler - appropriate coproc instr
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@ not recognised by VFP
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DBGSTR "not VFP"
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#ifdef CONFIG_PREEMPT
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get_thread_info r10
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ldr r4, [r10, #TI_PREEMPT] @ get preempt count
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sub r11, r4, #1 @ decrement it
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str r11, [r10, #TI_PREEMPT]
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#endif
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mov pc, lr
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process_exception:
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DBGSTR "bounce"
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mov r2, sp @ nothing stacked - regdump is at TOS
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mov lr, r9 @ setup for a return to the user code.
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@ Now call the C code to package up the bounce to the support code
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@ r0 holds the trigger instruction
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@ r1 holds the FPEXC value
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@ r2 pointer to register dump
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b VFP_bounce @ we have handled this - the support
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@ code will raise an exception if
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@ required. If not, the user code will
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@ retry the faulted instruction
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ENDPROC(vfp_support_entry)
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ENTRY(vfp_save_state)
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@ Save the current VFP state
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@ r0 - save location
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@ r1 - FPEXC
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DBGSTR1 "save VFP state %p", r0
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VFPFSTMIA r0, r2 @ save the working registers
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VFPFMRX r2, FPSCR @ current status
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tst r1, #FPEXC_EX @ is there additional state to save?
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beq 1f
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VFPFMRX r3, FPINST @ FPINST (only if FPEXC.EX is set)
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tst r1, #FPEXC_FP2V @ is there an FPINST2 to read?
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beq 1f
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VFPFMRX r12, FPINST2 @ FPINST2 if needed (and present)
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1:
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stmia r0, {r1, r2, r3, r12} @ save FPEXC, FPSCR, FPINST, FPINST2
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mov pc, lr
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ENDPROC(vfp_save_state)
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.align
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last_VFP_context_address:
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.word last_VFP_context
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.macro tbl_branch, base, tmp, shift
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#ifdef CONFIG_THUMB2_KERNEL
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adr \tmp, 1f
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add \tmp, \tmp, \base, lsl \shift
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mov pc, \tmp
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#else
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add pc, pc, \base, lsl \shift
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mov r0, r0
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#endif
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1:
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.endm
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ENTRY(vfp_get_float)
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tbl_branch r0, r3, #3
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.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
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1: mrc p10, 0, r0, c\dr, c0, 0 @ fmrs r0, s0
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mov pc, lr
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.org 1b + 8
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1: mrc p10, 0, r0, c\dr, c0, 4 @ fmrs r0, s1
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mov pc, lr
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.org 1b + 8
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.endr
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ENDPROC(vfp_get_float)
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ENTRY(vfp_put_float)
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tbl_branch r1, r3, #3
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.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
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1: mcr p10, 0, r0, c\dr, c0, 0 @ fmsr r0, s0
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mov pc, lr
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.org 1b + 8
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1: mcr p10, 0, r0, c\dr, c0, 4 @ fmsr r0, s1
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mov pc, lr
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.org 1b + 8
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.endr
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ENDPROC(vfp_put_float)
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ENTRY(vfp_get_double)
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tbl_branch r0, r3, #3
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.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
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1: fmrrd r0, r1, d\dr
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mov pc, lr
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.org 1b + 8
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.endr
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#ifdef CONFIG_VFPv3
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@ d16 - d31 registers
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.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
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1: mrrc p11, 3, r0, r1, c\dr @ fmrrd r0, r1, d\dr
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mov pc, lr
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.org 1b + 8
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.endr
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#endif
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@ virtual register 16 (or 32 if VFPv3) for compare with zero
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mov r0, #0
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mov r1, #0
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mov pc, lr
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ENDPROC(vfp_get_double)
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ENTRY(vfp_put_double)
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tbl_branch r2, r3, #3
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.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
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1: fmdrr d\dr, r0, r1
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mov pc, lr
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.org 1b + 8
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.endr
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#ifdef CONFIG_VFPv3
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@ d16 - d31 registers
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.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
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1: mcrr p11, 3, r0, r1, c\dr @ fmdrr r0, r1, d\dr
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mov pc, lr
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.org 1b + 8
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.endr
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#endif
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ENDPROC(vfp_put_double)
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