diff options
Diffstat (limited to 'arch/arm/vfp/vfphw.S')
| -rw-r--r-- | arch/arm/vfp/vfphw.S | 143 |
1 files changed, 87 insertions, 56 deletions
diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S index 9897dcfc16d..be807625ed8 100644 --- a/arch/arm/vfp/vfphw.S +++ b/arch/arm/vfp/vfphw.S @@ -14,19 +14,25 @@ * 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 <linux/init.h> +#include <linux/linkage.h> #include <asm/thread_info.h> #include <asm/vfpmacros.h> -#include "../kernel/entry-header.S" +#include <linux/kern_levels.h> +#include <asm/assembler.h> +#include <asm/asm-offsets.h> .macro DBGSTR, str #ifdef DEBUG stmfd sp!, {r0-r3, ip, lr} - add r0, pc, #4 + ldr r0, =1f bl printk - b 1f - .asciz "<7>VFP: \str\n" - .balign 4 -1: ldmfd sp!, {r0-r3, ip, lr} + ldmfd sp!, {r0-r3, ip, lr} + + .pushsection .rodata, "a" +1: .ascii KERN_DEBUG "VFP: \str\n" + .byte 0 + .previous #endif .endm @@ -34,12 +40,14 @@ #ifdef DEBUG stmfd sp!, {r0-r3, ip, lr} mov r1, \arg - add r0, pc, #4 + ldr r0, =1f bl printk - b 1f - .asciz "<7>VFP: \str\n" - .balign 4 -1: ldmfd sp!, {r0-r3, ip, lr} + ldmfd sp!, {r0-r3, ip, lr} + + .pushsection .rodata, "a" +1: .ascii KERN_DEBUG "VFP: \str\n" + .byte 0 + .previous #endif .endm @@ -49,55 +57,62 @@ mov r3, \arg3 mov r2, \arg2 mov r1, \arg1 - add r0, pc, #4 + ldr r0, =1f bl printk - b 1f - .asciz "<7>VFP: \str\n" - .balign 4 -1: ldmfd sp!, {r0-r3, ip, lr} + ldmfd sp!, {r0-r3, ip, lr} + + .pushsection .rodata, "a" +1: .ascii KERN_DEBUG "VFP: \str\n" + .byte 0 + .previous #endif .endm @ VFP hardware support entry point. @ -@ r0 = faulted instruction -@ r2 = faulted PC+4 -@ r9 = successful return +@ r0 = instruction opcode (32-bit ARM or two 16-bit Thumb) +@ r2 = PC value to resume execution after successful emulation +@ r9 = normal "successful" return address @ r10 = vfp_state union @ r11 = CPU number -@ lr = failure return - +@ lr = unrecognised instruction return address +@ IRQs enabled. ENTRY(vfp_support_entry) DBGSTR3 "instr %08x pc %08x state %p", r0, r2, r10 + ldr r3, [sp, #S_PSR] @ Neither lazy restore nor FP exceptions + and r3, r3, #MODE_MASK @ are supported in kernel mode + teq r3, #USR_MODE + bne vfp_kmode_exception @ Returns through lr + VFPFMRX r1, FPEXC @ Is the VFP enabled? DBGSTR1 "fpexc %08x", r1 tst r1, #FPEXC_EN bne look_for_VFP_exceptions @ VFP is already enabled DBGSTR1 "enable %x", r10 - ldr r3, last_VFP_context_address + ldr r3, vfp_current_hw_state_address orr r1, r1, #FPEXC_EN @ user FPEXC has the enable bit set - ldr r4, [r3, r11, lsl #2] @ last_VFP_context pointer + ldr r4, [r3, r11, lsl #2] @ vfp_current_hw_state pointer bic r5, r1, #FPEXC_EX @ 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. + cmp r4, r10 @ this thread owns the hw context? +#ifndef CONFIG_SMP + @ For UP, checking that this thread owns the hw context is + @ sufficient to determine that the hardware state is valid. + beq vfp_hw_state_valid + + @ On UP, we lazily save the VFP context. As a different + @ thread wants ownership of the VFP hardware, save the old + @ state if there was a previous (valid) owner. VFPFMXR FPEXC, r5 @ enable VFP, disable any pending @ exceptions, so we can get at the @ rest of it -#ifndef CONFIG_SMP - @ Save out the current registers to the old thread state - @ No need for SMP since this is not done lazily - DBGSTR1 "save old state %p", r4 - cmp r4, #0 - beq no_old_VFP_process + cmp r4, #0 @ if the vfp_current_hw_state is NULL + beq vfp_reload_hw @ then the hw state needs reloading VFPFSTMIA r4, r5 @ save the working registers VFPFMRX r5, FPSCR @ current status #ifndef CONFIG_CPU_FEROCEON @@ -110,13 +125,35 @@ ENTRY(vfp_support_entry) 1: #endif stmia r4, {r1, r5, r6, r8} @ save FPEXC, FPSCR, FPINST, FPINST2 - @ and point r4 at the word at the - @ start of the register dump +vfp_reload_hw: + +#else + @ For SMP, if this thread does not own the hw context, then we + @ need to reload it. No need to save the old state as on SMP, + @ we always save the state when we switch away from a thread. + bne vfp_reload_hw + + @ This thread has ownership of the current hardware context. + @ However, it may have been migrated to another CPU, in which + @ case the saved state is newer than the hardware context. + @ Check this by looking at the CPU number which the state was + @ last loaded onto. + ldr ip, [r10, #VFP_CPU] + teq ip, r11 + beq vfp_hw_state_valid + +vfp_reload_hw: + @ We're loading this threads state into the VFP hardware. Update + @ the CPU number which contains the most up to date VFP context. + str r11, [r10, #VFP_CPU] + + VFPFMXR FPEXC, r5 @ enable VFP, disable any pending + @ exceptions, so we can get at the + @ rest of it #endif -no_old_VFP_process: DBGSTR1 "load state %p", r10 - str r10, [r3, r11, lsl #2] @ update the last_VFP_context pointer + str r10, [r3, r11, lsl #2] @ update the vfp_current_hw_state pointer @ Load the saved state back into the VFP VFPFLDMIA r10, r5 @ reload the working registers while @ FPEXC is in a safe state @@ -132,21 +169,20 @@ no_old_VFP_process: #endif VFPFMXR FPSCR, r5 @ restore status -check_for_exception: +@ The context stored in the VFP hardware is up to date with this thread +vfp_hw_state_valid: tst r1, #FPEXC_EX 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 -#ifdef CONFIG_PREEMPT - get_thread_info r10 - ldr r4, [r10, #TI_PREEMPT] @ get preempt count - sub r11, r4, #1 @ decrement it - str r11, [r10, #TI_PREEMPT] -#endif + VFPFMXR FPEXC, r1 @ Restore FPEXC last + sub r2, r2, #4 @ Retry current instruction - if Thumb + str r2, [sp, #S_PC] @ mode it's two 16-bit instructions, + @ else it's one 32-bit instruction, so + @ always subtract 4 from the following + @ instruction address. + dec_preempt_count_ti r10, r4 mov pc, r9 @ we think we have handled things @@ -165,12 +201,7 @@ look_for_VFP_exceptions: @ not recognised by VFP DBGSTR "not VFP" -#ifdef CONFIG_PREEMPT - get_thread_info r10 - ldr r4, [r10, #TI_PREEMPT] @ get preempt count - sub r11, r4, #1 @ decrement it - str r11, [r10, #TI_PREEMPT] -#endif + dec_preempt_count_ti r10, r4 mov pc, lr process_exception: @@ -207,8 +238,8 @@ ENTRY(vfp_save_state) ENDPROC(vfp_save_state) .align -last_VFP_context_address: - .word last_VFP_context +vfp_current_hw_state_address: + .word vfp_current_hw_state .macro tbl_branch, base, tmp, shift #ifdef CONFIG_THUMB2_KERNEL |