powerpc: Call CPU ->restore callback earlier on secondary CPUs (ad0693ee) · Commits · 戴 / test

We do it before we loop on the PACA start flag. This way, we get a chance to set critical SPRs on all CPUs before Linux tries to start them up, which avoids problems when changing some bits such as LPCR bits that need to be identical on all threads of a core or similar things like that. Ideally, some of that should also be done before the MMU is enabled, but that's a separate issue which would require moving some of the SMP startup code earlier, let's not get there for now, it works with that change alone. Signed-off-by:

Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/head_64.S

+11 −11

Original line number	Diff line number	Diff line
		@@ -236,17 +236,6 @@ generic_secondary_common_init:

		/* From now on, r24 is expected to be logical cpuid */
		mr r24,r5
		3: HMT_LOW
		lbz r23,PACAPROCSTART(r13) /* Test if this processor should */
		/* start. */

		#ifndef CONFIG_SMP
		b 3b /* Never go on non-SMP */
		#else
		cmpwi 0,r23,0
		beq 3b /* Loop until told to go */

		sync /* order paca.run and cur_cpu_spec */

		/* See if we need to call a cpu state restore handler */
		LOAD_REG_ADDR(r23, cur_cpu_spec)
		@@ -258,6 +247,17 @@ generic_secondary_common_init:
		mtctr r23
		bctrl

		3: HMT_LOW
		lbz r23,PACAPROCSTART(r13) /* Test if this processor should */
		/* start. */
		#ifndef CONFIG_SMP
		b 3b /* Never go on non-SMP */
		#else
		cmpwi 0,r23,0
		beq 3b /* Loop until told to go */

		sync /* order paca.run and cur_cpu_spec */

		4: /* Create a temp kernel stack for use before relocation is on. */
		ld r1,PACAEMERGSP(r13)
		subi r1,r1,STACK_FRAME_OVERHEAD

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