diff options
Diffstat (limited to 'arch/arm/vfp/vfphw.S')
| -rw-r--r-- | arch/arm/vfp/vfphw.S | 63 |
1 files changed, 43 insertions, 20 deletions
diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S index 9897dcfc16d6..2d30c7f6edd3 100644 --- a/arch/arm/vfp/vfphw.S +++ b/arch/arm/vfp/vfphw.S @@ -77,27 +77,27 @@ ENTRY(vfp_support_entry) 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 +110,35 @@ 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 @@ -132,7 +154,8 @@ 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 @@ -207,8 +230,8 @@ 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 |