powerpc/8xx: Add a function to early map kernel via huge pages

Add a function to early map kernel memory using huge pages.

For 512k pages, just use standard page table and map in using 512k
pages.

For 8M pages, create a hugepd table and populate the two PGD
entries with it.

This function can only be used to create page tables at startup. Once
the regular SLAB allocation functions replace memblock functions,
this function cannot allocate new pages anymore. However it can still
update existing mappings with new protections.

hugepd_none() macro is moved into asm/hugetlb.h to be usable outside
of mm/hugetlbpage.c

early_pte_alloc_kernel() is made visible.

_PAGE_HUGE flag is now displayed by ptdump.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[mpe: Change ptdump display to use "huge"]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/68325bcd3b6f93127f7810418a2352c3519066d6.1589866984.git.christophe.leroy@csgroup.eu

diff --git a/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h b/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h
index 1c7d469..e752a58 100644 (file)
--- a/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h
+++ b/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h
@@ -35,6 +35,11 @@ static inline void hugepd_populate(hugepd_t *hpdp, pte_t *new, unsigned int pshi
        *hpdp = __hugepd(__pa(new) | _PMD_USER | _PMD_PRESENT | _PMD_PAGE_8M);
 }
 
+static inline void hugepd_populate_kernel(hugepd_t *hpdp, pte_t *new, unsigned int pshift)
+{
+       *hpdp = __hugepd(__pa(new) | _PMD_PRESENT | _PMD_PAGE_8M);
+}
+
 static inline int check_and_get_huge_psize(int shift)
 {
        return shift_to_mmu_psize(shift);

diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
index b1f1d53..961895b 100644 (file)
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h
@@ -107,6 +107,8 @@ unsigned long vmalloc_to_phys(void *vmalloc_addr);
 
 void pgtable_cache_add(unsigned int shift);
 
+pte_t *early_pte_alloc_kernel(pmd_t *pmdp, unsigned long va);
+
 #if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_PPC32)
 void mark_initmem_nx(void);
 #else

diff --git a/arch/powerpc/mm/nohash/8xx.c b/arch/powerpc/mm/nohash/8xx.c
index b735482..72fb75f 100644 (file)
--- a/arch/powerpc/mm/nohash/8xx.c
+++ b/arch/powerpc/mm/nohash/8xx.c
@@ -9,9 +9,11 @@
 
 #include <linux/memblock.h>
 #include <linux/mmu_context.h>
+#include <linux/hugetlb.h>
 #include <asm/fixmap.h>
 #include <asm/code-patching.h>
 #include <asm/inst.h>
+#include <asm/pgalloc.h>
 
 #include <mm/mmu_decl.h>
 
@@ -55,6 +57,56 @@ unsigned long p_block_mapped(phys_addr_t pa)
        return 0;
 }
 
+static pte_t __init *early_hugepd_alloc_kernel(hugepd_t *pmdp, unsigned long va)
+{
+       if (hpd_val(*pmdp) == 0) {
+               pte_t *ptep = memblock_alloc(sizeof(pte_basic_t), SZ_4K);
+
+               if (!ptep)
+                       return NULL;
+
+               hugepd_populate_kernel((hugepd_t *)pmdp, ptep, PAGE_SHIFT_8M);
+               hugepd_populate_kernel((hugepd_t *)pmdp + 1, ptep, PAGE_SHIFT_8M);
+       }
+       return hugepte_offset(*(hugepd_t *)pmdp, va, PGDIR_SHIFT);
+}
+
+static int __ref __early_map_kernel_hugepage(unsigned long va, phys_addr_t pa,
+                                            pgprot_t prot, int psize, bool new)
+{
+       pmd_t *pmdp = pmd_ptr_k(va);
+       pte_t *ptep;
+
+       if (WARN_ON(psize != MMU_PAGE_512K && psize != MMU_PAGE_8M))
+               return -EINVAL;
+
+       if (new) {
+               if (WARN_ON(slab_is_available()))
+                       return -EINVAL;
+
+               if (psize == MMU_PAGE_512K)
+                       ptep = early_pte_alloc_kernel(pmdp, va);
+               else
+                       ptep = early_hugepd_alloc_kernel((hugepd_t *)pmdp, va);
+       } else {
+               if (psize == MMU_PAGE_512K)
+                       ptep = pte_offset_kernel(pmdp, va);
+               else
+                       ptep = hugepte_offset(*(hugepd_t *)pmdp, va, PGDIR_SHIFT);
+       }
+
+       if (WARN_ON(!ptep))
+               return -ENOMEM;
+
+       /* The PTE should never be already present */
+       if (new && WARN_ON(pte_present(*ptep) && pgprot_val(prot)))
+               return -EINVAL;
+
+       set_huge_pte_at(&init_mm, va, ptep, pte_mkhuge(pfn_pte(pa >> PAGE_SHIFT, prot)));
+
+       return 0;
+}
+
 /*
  * MMU_init_hw does the chip-specific initialization of the MMU hardware.
  */

diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index bd0cb6e..05902bb 100644 (file)
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -61,7 +61,7 @@ static void __init *early_alloc_pgtable(unsigned long size)
        return ptr;
 }
 
-static pte_t __init *early_pte_alloc_kernel(pmd_t *pmdp, unsigned long va)
+pte_t __init *early_pte_alloc_kernel(pmd_t *pmdp, unsigned long va)
 {
        if (pmd_none(*pmdp)) {
                pte_t *ptep = early_alloc_pgtable(PTE_FRAG_SIZE);

diff --git a/arch/powerpc/mm/ptdump/8xx.c b/arch/powerpc/mm/ptdump/8xx.c
index 9e2d8e8..4bc3507 100644 (file)
--- a/arch/powerpc/mm/ptdump/8xx.c
+++ b/arch/powerpc/mm/ptdump/8xx.c
@@ -11,6 +11,11 @@
 
 static const struct flag_info flag_array[] = {
        {
+               .mask   = _PAGE_HUGE,
+               .val    = _PAGE_HUGE,
+               .set    = "huge",
+               .clear  = "    ",
+       }, {
                .mask   = _PAGE_SH,
                .val    = 0,
                .set    = "user",

diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index b0587b8..404f269 100644 (file)
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -56,6 +56,7 @@ config PPC_8xx
        select PPC_HAVE_KUEP
        select PPC_HAVE_KUAP
        select HAVE_ARCH_VMAP_STACK
+       select HUGETLBFS
 
 config 40x
        bool "AMCC 40x"