[PATCH 01/33] powerpc: use mm zones more sensibly

Christoph Hellwig
2018-10-09T13:25:29Z

Powerpc has somewhat odd usage where ZONE_DMA is used for all memory on
common 64-bit configfs, and ZONE_DMA32 is used for 31-bit schemes.

Move to a scheme closer to what other architectures use (and I dare to
say the intent of the system):

- ZONE_DMA: optionally for memory < 31-bit
- ZONE_NORMAL: everything addressable by the kernel
- ZONE_HIGHMEM: memory > 32-bit for 32-bit kernels

Also provide information on how ZONE_DMA is used by defining
ARCH_ZONE_DMA_BITS.

Contains various fixes from Benjamin Herrenschmidt.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
arch/powerpc/Kconfig | 6 +--
arch/powerpc/include/asm/page.h | 2 +
arch/powerpc/include/asm/pgtable.h | 1 -
arch/powerpc/kernel/dma-swiotlb.c | 6 +--
arch/powerpc/kernel/dma.c | 7 +--
arch/powerpc/mm/mem.c | 50 +++++++------------
arch/powerpc/platforms/85xx/corenet_generic.c | 10 ----
arch/powerpc/platforms/85xx/qemu_e500.c | 9 ----
include/linux/mmzone.h | 2 +-
9 files changed, 24 insertions(+), 69 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index a80669209155..06996df07cad 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -380,7 +380,7 @@ config PPC_ADV_DEBUG_DAC_RANGE
depends on PPC_ADV_DEBUG_REGS && 44x
default y

-config ZONE_DMA32
+config ZONE_DMA
bool
default y if PPC64

@@ -879,10 +879,6 @@ config ISA
have an IBM RS/6000 or pSeries machine, say Y. If you have an
embedded board, consult your board documentation.

-config ZONE_DMA
- bool
- default y
-
config GENERIC_ISA_DMA
bool
depends on ISA_DMA_API
diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
index f6a1265face2..fc8c9ac0c6be 100644
--- a/arch/powerpc/include/asm/page.h
+++ b/arch/powerpc/include/asm/page.h
@@ -354,4 +354,6 @@ typedef struct page *pgtable_t;
#endif /* __ASSEMBLY__ */
#include <asm/slice.h>

+#define ARCH_ZONE_DMA_BITS 31
+
#endif /* _ASM_POWERPC_PAGE_H */
diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
index 14c79a7dc855..9bafb38e959e 100644
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h
@@ -37,7 +37,6 @@ extern unsigned long empty_zero_page[];

extern pgd_t swapper_pg_dir[];

-void limit_zone_pfn(enum zone_type zone, unsigned long max_pfn);
int dma_pfn_limit_to_zone(u64 pfn_limit);
extern void paging_init(void);

diff --git a/arch/powerpc/kernel/dma-swiotlb.c b/arch/powerpc/kernel/dma-swiotlb.c
index 88f3963ca30f..93a4622563c6 100644
--- a/arch/powerpc/kernel/dma-swiotlb.c
+++ b/arch/powerpc/kernel/dma-swiotlb.c
@@ -108,12 +108,8 @@ int __init swiotlb_setup_bus_notifier(void)

void __init swiotlb_detect_4g(void)
{
- if ((memblock_end_of_DRAM() - 1) > 0xffffffff) {
+ if ((memblock_end_of_DRAM() - 1) > 0xffffffff)
ppc_swiotlb_enable = 1;
-#ifdef CONFIG_ZONE_DMA32
- limit_zone_pfn(ZONE_DMA32, (1ULL << 32) >> PAGE_SHIFT);
-#endif
- }
}

static int __init check_swiotlb_enabled(void)
diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
index dbfc7056d7df..6551685a4ed0 100644
--- a/arch/powerpc/kernel/dma.c
+++ b/arch/powerpc/kernel/dma.c
@@ -50,7 +50,7 @@ static int dma_nommu_dma_supported(struct device *dev, u64 mask)
return 1;

#ifdef CONFIG_FSL_SOC
- /* Freescale gets another chance via ZONE_DMA/ZONE_DMA32, however
+ /* Freescale gets another chance via ZONE_DMA, however
* that will have to be refined if/when they support iommus
*/
return 1;
@@ -94,13 +94,10 @@ void *__dma_nommu_alloc_coherent(struct device *dev, size_t size,
}

switch (zone) {
+#ifdef CONFIG_ZONE_DMA
case ZONE_DMA:
flag |= GFP_DMA;
break;
-#ifdef CONFIG_ZONE_DMA32
- case ZONE_DMA32:
- flag |= GFP_DMA32;
- break;
#endif
};
#endif /* CONFIG_FSL_SOC */
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 5c8530d0c611..8bff7e893bde 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -69,15 +69,12 @@ pte_t *kmap_pte;
EXPORT_SYMBOL(kmap_pte);
pgprot_t kmap_prot;
EXPORT_SYMBOL(kmap_prot);
-#define TOP_ZONE ZONE_HIGHMEM

static inline pte_t *virt_to_kpte(unsigned long vaddr)
{
return pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr),
vaddr), vaddr), vaddr);
}
-#else
-#define TOP_ZONE ZONE_NORMAL
#endif

int page_is_ram(unsigned long pfn)
@@ -246,35 +243,19 @@ static int __init mark_nonram_nosave(void)
}
#endif

-static bool zone_limits_final;
-
-/*
- * The memory zones past TOP_ZONE are managed by generic mm code.
- * These should be set to zero since that's what every other
- * architecture does.
- */
-static unsigned long max_zone_pfns[MAX_NR_ZONES] = {
- [0 ... TOP_ZONE ] = ~0UL,
- [TOP_ZONE + 1 ... MAX_NR_ZONES - 1] = 0
-};
-
/*
- * Restrict the specified zone and all more restrictive zones
- * to be below the specified pfn. May not be called after
- * paging_init().
+ * Zones usage:
+ *
+ * We setup ZONE_DMA to be 31-bits on all platforms and ZONE_NORMAL to be
+ * everything else. GFP_DMA32 page allocations automatically fall back to
+ * ZONE_DMA.
+ *
+ * By using 31-bit unconditionally, we can exploit ARCH_ZONE_DMA_BITS to
+ * inform the generic DMA mapping code. 32-bit only devices (if not handled
+ * by an IOMMU anyway) will take a first dip into ZONE_NORMAL and get
+ * otherwise served by ZONE_DMA.
*/
-void __init limit_zone_pfn(enum zone_type zone, unsigned long pfn_limit)
-{
- int i;
-
- if (WARN_ON(zone_limits_final))
- return;
-
- for (i = zone; i >= 0; i--) {
- if (max_zone_pfns[i] > pfn_limit)
- max_zone_pfns[i] = pfn_limit;
- }
-}
+static unsigned long max_zone_pfns[MAX_NR_ZONES];

/*
* Find the least restrictive zone that is entirely below the
@@ -324,11 +305,14 @@ void __init paging_init(void)
printk(KERN_DEBUG "Memory hole size: %ldMB\n",
(long int)((top_of_ram - total_ram) >> 20));

+#ifdef CONFIG_ZONE_DMA
+ max_zone_pfns[ZONE_DMA] = min(max_low_pfn, 0x7fffffffUL >> PAGE_SHIFT);
+#endif
+ max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
#ifdef CONFIG_HIGHMEM
- limit_zone_pfn(ZONE_NORMAL, lowmem_end_addr >> PAGE_SHIFT);
+ max_zone_pfns[ZONE_HIGHMEM] = max_pfn
#endif
- limit_zone_pfn(TOP_ZONE, top_of_ram >> PAGE_SHIFT);
- zone_limits_final = true;
+
free_area_init_nodes(max_zone_pfns);

mark_nonram_nosave();
diff --git a/arch/powerpc/platforms/85xx/corenet_generic.c b/arch/powerpc/platforms/85xx/corenet_generic.c
index ac191a7a1337..b0dac307bebf 100644
--- a/arch/powerpc/platforms/85xx/corenet_generic.c
+++ b/arch/powerpc/platforms/85xx/corenet_generic.c
@@ -68,16 +68,6 @@ void __init corenet_gen_setup_arch(void)

swiotlb_detect_4g();

-#if defined(CONFIG_FSL_PCI) && defined(CONFIG_ZONE_DMA32)
- /*
- * Inbound windows don't cover the full lower 4 GiB
- * due to conflicts with PCICSRBAR and outbound windows,
- * so limit the DMA32 zone to 2 GiB, to allow consistent
- * allocations to succeed.
- */
- limit_zone_pfn(ZONE_DMA32, 1UL << (31 - PAGE_SHIFT));
-#endif
-
pr_info("%s board\n", ppc_md.name);

mpc85xx_qe_init();
diff --git a/arch/powerpc/platforms/85xx/qemu_e500.c b/arch/powerpc/platforms/85xx/qemu_e500.c
index b63a8548366f..27631c607f3d 100644
--- a/arch/powerpc/platforms/85xx/qemu_e500.c
+++ b/arch/powerpc/platforms/85xx/qemu_e500.c
@@ -45,15 +45,6 @@ static void __init qemu_e500_setup_arch(void)

fsl_pci_assign_primary();
swiotlb_detect_4g();
-#if defined(CONFIG_FSL_PCI) && defined(CONFIG_ZONE_DMA32)
- /*
- * Inbound windows don't cover the full lower 4 GiB
- * due to conflicts with PCICSRBAR and outbound windows,
- * so limit the DMA32 zone to 2 GiB, to allow consistent
- * allocations to succeed.
- */
- limit_zone_pfn(ZONE_DMA32, 1UL << (31 - PAGE_SHIFT));
-#endif
mpc85xx_smp_init();
}

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 1e22d96734e0..68970340df1c 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -312,7 +312,7 @@ enum zone_type {
* Architecture Limit
* ---------------------------
* parisc, ia64, sparc <4G
- * s390 <2G
+ * s390, powerpc <2G
* arm Various
* alpha Unlimited or 0-16MB.
*
--
2.19.0