[ARM] 4111/1: Allow VFP to work with thread migration on SMP (c6428464) · Commits · 戴 / test

arch/arm/vfp/entry.S

+1 −0

Original line number	Diff line number	Diff line
		@@ -25,6 +25,7 @@
		do_vfp:
		enable_irq
		ldr r4, .LCvfp
		ldr r11, [r10, #TI_CPU] @ CPU number
		add r10, r10, #TI_VFPSTATE @ r10 = workspace
		ldr pc, [r4] @ call VFP entry point

arch/arm/vfp/vfp.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -370,3 +370,7 @@ struct op {
		u32 (* const fn)(int dd, int dn, int dm, u32 fpscr);
		u32 flags;
		};

		#ifdef CONFIG_SMP
		extern void vfp_save_state(void *location, u32 fpexc);
		#endif

arch/arm/vfp/vfphw.S

+24 −2

Original line number	Diff line number	Diff line
		@@ -65,6 +65,7 @@
		@ r2 = faulted PC+4
		@ r9 = successful return
		@ r10 = vfp_state union
		@ r11 = CPU number
		@ lr = failure return

		.globl vfp_support_entry
		@@ -79,7 +80,7 @@ vfp_support_entry:
		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
		ldr r4, [r3, r11, lsl #2] @ 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
		@@ -91,7 +92,9 @@ vfp_support_entry:
		@ 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
		@@ -105,10 +108,11 @@ vfp_support_entry:
		stmia r4, {r1, r5, r6, r8} @ save FPEXC, FPSCR, FPINST, FPINST2
		@ and point r4 at the word at the
		@ start of the register dump
		#endif

		no_old_VFP_process:
		DBGSTR1 "load state %p", r10
		str r10, [r3] @ update the last_VFP_context pointer
		str r10, [r3, r11, lsl #2] @ update the last_VFP_context pointer
		@ Load the saved state back into the VFP
		VFPFLDMIA r10 @ reload the working registers while
		@ FPEXC is in a safe state
		@@ -162,6 +166,24 @@ process_exception:
		@ required. If not, the user code will
		@ retry the faulted instruction

		#ifdef CONFIG_SMP
		.globl vfp_save_state
		.type vfp_save_state, %function
		vfp_save_state:
		@ Save the current VFP state
		@ r0 - save location
		@ r1 - FPEXC
		DBGSTR1 "save VFP state %p", r0
		VFPFMRX r2, FPSCR @ current status
		VFPFMRX r3, FPINST @ FPINST (always there, rev0 onwards)
		tst r1, #FPEXC_FPV2 @ is there an FPINST2 to read?
		VFPFMRX r12, FPINST2, NE @ FPINST2 if needed - avoids reading
		@ nonexistant reg on rev0
		VFPFSTMIA r0 @ save the working registers
		stmia r0, {r1, r2, r3, r12} @ save FPEXC, FPSCR, FPINST, FPINST2
		mov pc, lr
		#endif

		last_VFP_context_address:
		.word last_VFP_context

arch/arm/vfp/vfpmodule.c

+26 −4

Original line number	Diff line number	Diff line
		@@ -28,7 +28,7 @@ void vfp_testing_entry(void);
		void vfp_support_entry(void);

		void (*vfp_vector)(void) = vfp_testing_entry;
		union vfp_state *last_VFP_context;
		union vfp_state *last_VFP_context[NR_CPUS];

		/*
		* Dual-use variable.
		@@ -41,13 +41,35 @@ static int vfp_notifier(struct notifier_block self, unsigned long cmd, void v)
		{
		struct thread_info *thread = v;
		union vfp_state *vfp;
		__u32 cpu = thread->cpu;

		if (likely(cmd == THREAD_NOTIFY_SWITCH)) {
		u32 fpexc = fmrx(FPEXC);

		#ifdef CONFIG_SMP
		/*
		* On SMP, if VFP is enabled, save the old state in
		* case the thread migrates to a different CPU. The
		* restoring is done lazily.
		*/
		if ((fpexc & FPEXC_ENABLE) && last_VFP_context[cpu]) {
		vfp_save_state(last_VFP_context[cpu], fpexc);
		last_VFP_context[cpu]->hard.cpu = cpu;
		}
		/*
		* Thread migration, just force the reloading of the
		* state on the new CPU in case the VFP registers
		* contain stale data.
		*/
		if (thread->vfpstate.hard.cpu != cpu)
		last_VFP_context[cpu] = NULL;
		#endif

		/*
		* Always disable VFP so we can lazily save/restore the
		* old state.
		*/
		fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_ENABLE);
		fmxr(FPEXC, fpexc & ~FPEXC_ENABLE);
		return NOTIFY_DONE;
		}

		@@ -68,8 +90,8 @@ static int vfp_notifier(struct notifier_block self, unsigned long cmd, void v)
		}

		/* flush and release case: Per-thread VFP cleanup. */
		if (last_VFP_context == vfp)
		last_VFP_context = NULL;
		if (last_VFP_context[cpu] == vfp)
		last_VFP_context[cpu] = NULL;

		return NOTIFY_DONE;
		}

include/asm-arm/fpstate.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -35,6 +35,9 @@ struct vfp_hard_struct {
		*/
		__u32 fpinst;
		__u32 fpinst2;
		#ifdef CONFIG_SMP
		__u32 cpu;
		#endif
		};

		union vfp_state {

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