[PATCH 1/2] powerpc/64e: Add __ref to early_alloc_pgtable()

This silences a section mismatch warning.  early_alloc_pgtable() is
called from map_kernel_page() which cannot be __init, but only when
slab_is_available() returns false which can only happen during early
boot.

Signed-off-by: Scott Wood <redacted>
---
 arch/powerpc/mm/pgtable_64.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c
index f6ce1f1..3b3c4d3 100644
--- a/arch/powerpc/mm/pgtable_64.c
+++ b/arch/powerpc/mm/pgtable_64.c

@@ -68,7 +68,7 @@
 unsigned long ioremap_bot = IOREMAP_BASE;
 
 #ifdef CONFIG_PPC_MMU_NOHASH
-static void *early_alloc_pgtable(unsigned long size)
+static __ref void *early_alloc_pgtable(unsigned long size)
 {
 	void *pt;
 

-- 
1.9.1

__early_init_mmu() does some things that are really only needed by the
boot cpu.  On FSL booke, This includes calling
memblock_enforce_memory_limit(), which is labelled __init.  Secondary
cpu init code can't be __init as that would break CPU hotplug.

While it's probably a bug that memblock_enforce_memory_limit() isn't
__init_memblock instead, there's no reason why we should be doing this
stuff for secondary cpus in the first place.

Signed-off-by: Scott Wood <redacted>
---
 arch/powerpc/mm/tlb_nohash.c | 90 ++++++++++++++++++++++----------------------
 1 file changed, 46 insertions(+), 44 deletions(-)

diff --git a/arch/powerpc/mm/tlb_nohash.c b/arch/powerpc/mm/tlb_nohash.c
index 92cb18d..11ece11 100644
--- a/arch/powerpc/mm/tlb_nohash.c
+++ b/arch/powerpc/mm/tlb_nohash.c

@@ -581,42 +581,10 @@ static void setup_mmu_htw(void)
 /*
  * Early initialization of the MMU TLB code
  */
-static void __early_init_mmu(int boot_cpu)
+static void early_init_mmu_allcpus(void)
 {
 	unsigned int mas4;
 
-	/* XXX This will have to be decided at runtime, but right
-	 * now our boot and TLB miss code hard wires it. Ideally
-	 * we should find out a suitable page size and patch the
-	 * TLB miss code (either that or use the PACA to store
-	 * the value we want)
-	 */
-	mmu_linear_psize = MMU_PAGE_1G;
-
-	/* XXX This should be decided at runtime based on supported
-	 * page sizes in the TLB, but for now let's assume 16M is
-	 * always there and a good fit (which it probably is)
-	 *
-	 * Freescale booke only supports 4K pages in TLB0, so use that.
-	 */
-	if (mmu_has_feature(MMU_FTR_TYPE_FSL_E))
-		mmu_vmemmap_psize = MMU_PAGE_4K;
-	else
-		mmu_vmemmap_psize = MMU_PAGE_16M;
-
-	/* XXX This code only checks for TLB 0 capabilities and doesn't
-	 *     check what page size combos are supported by the HW. It
-	 *     also doesn't handle the case where a separate array holds
-	 *     the IND entries from the array loaded by the PT.
-	 */
-	if (boot_cpu) {
-		/* Look for supported page sizes */
-		setup_page_sizes();
-
-		/* Look for HW tablewalk support */
-		setup_mmu_htw();
-	}
-
 	/* Set MAS4 based on page table setting */
 
 	mas4 = 0x4 << MAS4_WIMGED_SHIFT;

@@ -650,11 +618,6 @@ static void __early_init_mmu(int boot_cpu)
 	}
 	mtspr(SPRN_MAS4, mas4);
 
-	/* Set the global containing the top of the linear mapping
-	 * for use by the TLB miss code
-	 */
-	linear_map_top = memblock_end_of_DRAM();
-
 #ifdef CONFIG_PPC_FSL_BOOK3E
 	if (mmu_has_feature(MMU_FTR_TYPE_FSL_E)) {
 		unsigned int num_cams;

@@ -662,7 +625,51 @@ static void __early_init_mmu(int boot_cpu)
 		/* use a quarter of the TLBCAM for bolted linear map */
 		num_cams = (mfspr(SPRN_TLB1CFG) & TLBnCFG_N_ENTRY) / 4;
 		linear_map_top = map_mem_in_cams(linear_map_top, num_cams);
+	}
+#endif
+}
 
+void __init early_init_mmu(void)
+{
+	/* XXX This will have to be decided at runtime, but right
+	 * now our boot and TLB miss code hard wires it. Ideally
+	 * we should find out a suitable page size and patch the
+	 * TLB miss code (either that or use the PACA to store
+	 * the value we want)
+	 */
+	mmu_linear_psize = MMU_PAGE_1G;
+
+	/* XXX This should be decided at runtime based on supported
+	 * page sizes in the TLB, but for now let's assume 16M is
+	 * always there and a good fit (which it probably is)
+	 *
+	 * Freescale booke only supports 4K pages in TLB0, so use that.
+	 */
+	if (mmu_has_feature(MMU_FTR_TYPE_FSL_E))
+		mmu_vmemmap_psize = MMU_PAGE_4K;
+	else
+		mmu_vmemmap_psize = MMU_PAGE_16M;
+
+	/* XXX This code only checks for TLB 0 capabilities and doesn't
+	 *     check what page size combos are supported by the HW. It
+	 *     also doesn't handle the case where a separate array holds
+	 *     the IND entries from the array loaded by the PT.
+	 */
+	/* Look for supported page sizes */
+	setup_page_sizes();
+
+	/* Look for HW tablewalk support */
+	setup_mmu_htw();
+
+	/* Set the global containing the top of the linear mapping
+	 * for use by the TLB miss code
+	 */
+	linear_map_top = memblock_end_of_DRAM();
+
+	early_init_mmu_allcpus();
+
+#ifdef CONFIG_PPC_FSL_BOOK3E
+	if (mmu_has_feature(MMU_FTR_TYPE_FSL_E)) {
 		/* limit memory so we dont have linear faults */
 		memblock_enforce_memory_limit(linear_map_top);
 

@@ -683,14 +690,9 @@ static void __early_init_mmu(int boot_cpu)
 	memblock_set_current_limit(linear_map_top);
 }
 
-void __init early_init_mmu(void)
-{
-	__early_init_mmu(1);
-}
-
 void early_init_mmu_secondary(void)
 {
-	__early_init_mmu(0);
+	early_init_mmu_allcpus();
 }
 
 void setup_initial_memory_limit(phys_addr_t first_memblock_base,

-- 
1.9.1

On Fri, 2014-08-01 at 22:07 -0500, Scott Wood wrote:

 
-void __init early_init_mmu(void)
-{
-	__early_init_mmu(1);
-}
-
 void early_init_mmu_secondary(void)
 {
-	__early_init_mmu(0);
+	early_init_mmu_allcpus();
 }

Small nit, it took me 30s too long to figure out what you were doing due
to the naming above :)

Call the latter early_init_this_mmu() and keep the global one separate
such that early_init_mmu() does:

	early_init_mmu_common();
	early_init_this_mmu();

Cheers,
Ben.

On Tue, 2014-08-05 at 14:36 +1000, Benjamin Herrenschmidt wrote:

On Fri, 2014-08-01 at 22:07 -0500, Scott Wood wrote:

quoted

 
-void __init early_init_mmu(void)
-{
-	__early_init_mmu(1);
-}
-
 void early_init_mmu_secondary(void)
 {
-	__early_init_mmu(0);
+	early_init_mmu_allcpus();
 }

Small nit, it took me 30s too long to figure out what you were doing due
to the naming above :)

Call the latter early_init_this_mmu() and keep the global one separate
such that early_init_mmu() does:

	early_init_mmu_common();
	early_init_this_mmu();

I'll do s/mmu_allcpus/this_mmu/ but early_init_mmu() needs to do things
both before and after early_init_mmu_common().  Do you want two new
functions (before and after) or is it OK to just rename
early_init_mmu_allcpus() and put a comment before early_init_mmu()
saying it's just for the boot cpu?

-Scott

On Tue, 2014-08-05 at 19:48 -0500, Scott Wood wrote:

I'll do s/mmu_allcpus/this_mmu/ but early_init_mmu() needs to do things
both before and after early_init_mmu_common().  Do you want two new
functions (before and after) or is it OK to just rename
early_init_mmu_allcpus() and put a comment before early_init_mmu()
saying it's just for the boot cpu?

Do we really need that before/after ? The "after" code is the linear
mapping setup but does it rely on the MAS4 setting done above ?

Otherwise you can do before/after using a separate function
mmu_set_linear_map()

Always nicer to break down too large functions anyway.

Cheers,
Ben.

On Wed, 2014-08-06 at 14:58 +1000, Benjamin Herrenschmidt wrote:

On Tue, 2014-08-05 at 19:48 -0500, Scott Wood wrote:

quoted

I'll do s/mmu_allcpus/this_mmu/ but early_init_mmu() needs to do things
both before and after early_init_mmu_common().  Do you want two new
functions (before and after) or is it OK to just rename
early_init_mmu_allcpus() and put a comment before early_init_mmu()
saying it's just for the boot cpu?

Do we really need that before/after ? The "after" code is the linear
mapping setup but does it rely on the MAS4 setting done above ?

No, but it relies on the call to map_mem_in_cams() to determine how much
memory was able to be mapped.

Otherwise you can do before/after using a separate function
mmu_set_linear_map()

OK.

Always nicer to break down too large functions anyway.

Usually yes, but it doesn't necessarily help when it's an arbitrary
division of a function that is a list of simple things (as opposed to
e.g. factoring out the #ifdef CONFIG_PPC_FSL_BOOK3E block into its own
function).

BTW, is there a particular reason why we need to use
memblock_enforce_memory_limit() on FSL_BOOK3E, rather than relying on
memblock_set_current_limit()?  I see that when
memblock_enforce_memory_limit() was added to __early_init_mmu(),
memblock_set_current_limit() did not exist.  On 32-bit fsl booke uses
memblock_set_current_limit() for this.

-Scott

On Wed, 2014-08-06 at 15:09 -0500, Scott Wood wrote:

BTW, is there a particular reason why we need to use
memblock_enforce_memory_limit() on FSL_BOOK3E, rather than relying on
memblock_set_current_limit()?  I see that when
memblock_enforce_memory_limit() was added to __early_init_mmu(),
memblock_set_current_limit() did not exist.  On 32-bit fsl booke uses
memblock_set_current_limit() for this.

I don't remember. I don't even know what the difference is, I can
have a look later if you want but I'd rather you did :-)

Cheers,
Ben.