[PATCH 4/5] mm/vmalloc: remove unmap_kernel_range

Nicholas Piggin
2021-01-26T23:17:34Z

This is a shim around vunmap_range, get rid of it.

Move the main API comment from the _noflush variant to the normal
variant, and make _noflush internal to mm/.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
Documentation/core-api/cachetlb.rst | 2 +-
arch/arm64/mm/init.c | 2 +-
arch/powerpc/kernel/isa-bridge.c | 4 +-
arch/powerpc/kernel/pci_64.c | 2 +-
arch/powerpc/mm/ioremap.c | 2 +-
drivers/pci/pci.c | 2 +-
include/linux/vmalloc.h | 8 +---
mm/internal.h | 1 +
mm/percpu-vm.c | 2 +-
mm/vmalloc.c | 59 ++++++++++++++---------------
10 files changed, 38 insertions(+), 46 deletions(-)

diff --git a/Documentation/core-api/cachetlb.rst b/Documentation/core-api/cachetlb.rst
index 756f7bcf8191..fe4290e26729 100644
--- a/Documentation/core-api/cachetlb.rst
+++ b/Documentation/core-api/cachetlb.rst
@@ -215,7 +215,7 @@ Here are the routines, one by one:

The first of these two routines is invoked after vmap_range()
has installed the page table entries. The second is invoked
- before unmap_kernel_range() deletes the page table entries.
+ before vunmap_range() deletes the page table entries.

There exists another whole class of cpu cache issues which currently
require a whole different set of interfaces to handle properly.
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 709d98fea90c..7fe0a5074205 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -498,7 +498,7 @@ void free_initmem(void)
* prevents the region from being reused for kernel modules, which
* is not supported by kallsyms.
*/
- unmap_kernel_range((u64)__init_begin, (u64)(__init_end - __init_begin));
+ vunmap_range((u64)__init_begin, (u64)__init_end);
}

void dump_mem_limit(void)
diff --git a/arch/powerpc/kernel/isa-bridge.c b/arch/powerpc/kernel/isa-bridge.c
index 2257d24e6a26..39c625737c09 100644
--- a/arch/powerpc/kernel/isa-bridge.c
+++ b/arch/powerpc/kernel/isa-bridge.c
@@ -48,7 +48,7 @@ static void remap_isa_base(phys_addr_t pa, unsigned long size)
if (slab_is_available()) {
if (ioremap_page_range(ISA_IO_BASE, ISA_IO_BASE + size, pa,
pgprot_noncached(PAGE_KERNEL)))
- unmap_kernel_range(ISA_IO_BASE, size);
+ vunmap_range(ISA_IO_BASE, ISA_IO_BASE + size);
} else {
early_ioremap_range(ISA_IO_BASE, pa, size,
pgprot_noncached(PAGE_KERNEL));
@@ -311,7 +311,7 @@ static void isa_bridge_remove(void)
isa_bridge_pcidev = NULL;

/* Unmap the ISA area */
- unmap_kernel_range(ISA_IO_BASE, 0x10000);
+ vunmap_range(ISA_IO_BASE, ISA_IO_BASE + 0x10000);
}

/**
diff --git a/arch/powerpc/kernel/pci_64.c b/arch/powerpc/kernel/pci_64.c
index 9312e6eda7ff..3fb7e572abed 100644
--- a/arch/powerpc/kernel/pci_64.c
+++ b/arch/powerpc/kernel/pci_64.c
@@ -140,7 +140,7 @@ void __iomem *ioremap_phb(phys_addr_t paddr, unsigned long size)
addr = (unsigned long)area->addr;
if (ioremap_page_range(addr, addr + size, paddr,
pgprot_noncached(PAGE_KERNEL))) {
- unmap_kernel_range(addr, size);
+ vunmap_range(addr, addr + size);
return NULL;
}

diff --git a/arch/powerpc/mm/ioremap.c b/arch/powerpc/mm/ioremap.c
index b1a0aebe8c48..57342154d2b0 100644
--- a/arch/powerpc/mm/ioremap.c
+++ b/arch/powerpc/mm/ioremap.c
@@ -93,7 +93,7 @@ void __iomem *do_ioremap(phys_addr_t pa, phys_addr_t offset, unsigned long size,
if (!ret)
return (void __iomem *)area->addr + offset;

- unmap_kernel_range(va, size);
+ vunmap_range(va, va + size);
free_vm_area(area);

return NULL;
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index b9fecc25d213..d1e5ee09b381 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4107,7 +4107,7 @@ void pci_unmap_iospace(struct resource *res)
#if defined(PCI_IOBASE) && defined(CONFIG_MMU)
unsigned long vaddr = (unsigned long)PCI_IOBASE + res->start;

- unmap_kernel_range(vaddr, resource_size(res));
+ vunmap_range(vaddr, vaddr + resource_size(res));
#endif
}
EXPORT_SYMBOL(pci_unmap_iospace);
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 913c9d4f5e03..b569a13c9960 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -217,8 +217,7 @@ static inline bool is_vm_area_hugepages(const void *addr)
int vmap_range(unsigned long addr, unsigned long end,
phys_addr_t phys_addr, pgprot_t prot,
unsigned int max_page_shift);
-extern void unmap_kernel_range_noflush(unsigned long addr, unsigned long size);
-extern void unmap_kernel_range(unsigned long addr, unsigned long size);
+void vunmap_range(unsigned long addr, unsigned long end);
static inline void set_vm_flush_reset_perms(void *addr)
{
struct vm_struct *vm = find_vm_area(addr);
@@ -228,11 +227,6 @@ static inline void set_vm_flush_reset_perms(void *addr)
}

#else
-static inline void
-unmap_kernel_range_noflush(unsigned long addr, unsigned long size)
-{
-}
-#define unmap_kernel_range unmap_kernel_range_noflush
static inline void set_vm_flush_reset_perms(void *addr)
{
}
diff --git a/mm/internal.h b/mm/internal.h
index 3ce246945882..3d4449f79582 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -628,5 +628,6 @@ struct migration_target_control {
*/
int vmap_pages_range_noflush(unsigned long addr, unsigned long end,
pgprot_t prot, struct page **pages, unsigned int page_shift);
+void vunmap_range_noflush(unsigned long start, unsigned long end);

#endif /* __MM_INTERNAL_H */
diff --git a/mm/percpu-vm.c b/mm/percpu-vm.c
index 88a53eb68a94..8d3844bc0c7c 100644
--- a/mm/percpu-vm.c
+++ b/mm/percpu-vm.c
@@ -134,7 +134,7 @@ static void pcpu_pre_unmap_flush(struct pcpu_chunk *chunk,

static void __pcpu_unmap_pages(unsigned long addr, int nr_pages)
{
- unmap_kernel_range_noflush(addr, nr_pages << PAGE_SHIFT);
+ vunmap_range_noflush(addr, addr + (nr_pages << PAGE_SHIFT));
}

/**
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 78dc3ec457ef..5ff190590fe4 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -378,22 +378,20 @@ static void vunmap_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
} while (p4d++, addr = next, addr != end);
}

-/**
- * unmap_kernel_range_noflush - unmap kernel VM area
- * @start: start of the VM area to unmap
- * @size: size of the VM area to unmap
+/*
+ * vunmap_range_noflush is similar to vunmap_range, but does not
+ * flush caches or TLBs.
*
- * Unmap PFN_UP(@size) pages at @addr. The VM area @addr and @size specify
- * should have been allocated using get_vm_area() and its friends.
+ * The caller is responsible for calling flush_cache_vmap() before calling
+ * this function, and flush_tlb_kernel_range after it has returned
+ * successfully (and before the addresses are expected to cause a page fault
+ * or be re-mapped for something else, if TLB flushes are being delayed or
+ * coalesced).
*
- * NOTE:
- * This function does NOT do any cache flushing. The caller is responsible
- * for calling flush_cache_vunmap() on to-be-mapped areas before calling this
- * function and flush_tlb_kernel_range() after.
+ * This is an internal function only. Do not use outside mm/.
*/
-void unmap_kernel_range_noflush(unsigned long start, unsigned long size)
+void vunmap_range_noflush(unsigned long start, unsigned long end)
{
- unsigned long end = start + size;
unsigned long next;
pgd_t *pgd;
unsigned long addr = start;
@@ -414,6 +412,22 @@ void unmap_kernel_range_noflush(unsigned long start, unsigned long size)
arch_sync_kernel_mappings(start, end);
}

+/**
+ * vunmap_range_noflush - unmap kernel virtual addresses
+ * @addr: start of the VM area to unmap
+ * @end: end of the VM area to unmap (non-inclusive)
+ *
+ * Clears any present PTEs in the virtual address range, flushes TLBs and
+ * caches. Any subsequent access to the address before it has been re-mapped
+ * is a kernel bug.
+ */
+void vunmap_range(unsigned long addr, unsigned long end)
+{
+ flush_cache_vunmap(addr, end);
+ vunmap_range_noflush(addr, end);
+ flush_tlb_kernel_range(addr, end);
+}
+
static int vmap_pages_pte_range(pmd_t *pmd, unsigned long addr,
unsigned long end, pgprot_t prot, struct page **pages, int *nr,
pgtbl_mod_mask *mask)
@@ -1712,7 +1726,7 @@ static void free_vmap_area_noflush(struct vmap_area *va)
static void free_unmap_vmap_area(struct vmap_area *va)
{
flush_cache_vunmap(va->va_start, va->va_end);
- unmap_kernel_range_noflush(va->va_start, va->va_end - va->va_start);
+ vunmap_range_noflush(va->va_start, va->va_end);
if (debug_pagealloc_enabled_static())
flush_tlb_kernel_range(va->va_start, va->va_end);

@@ -1990,7 +2004,7 @@ static void vb_free(unsigned long addr, unsigned long size)
offset = (addr & (VMAP_BLOCK_SIZE - 1)) >> PAGE_SHIFT;
vb = xa_load(&vmap_blocks, addr_to_vb_idx(addr));

- unmap_kernel_range_noflush(addr, size);
+ vunmap_range_noflush(addr, addr + size);

if (debug_pagealloc_enabled_static())
flush_tlb_kernel_range(addr, addr + size);
@@ -2307,23 +2321,6 @@ void __init vmalloc_init(void)
vmap_initialized = true;
}

-/**
- * unmap_kernel_range - unmap kernel VM area and flush cache and TLB
- * @addr: start of the VM area to unmap
- * @size: size of the VM area to unmap
- *
- * Similar to unmap_kernel_range_noflush() but flushes vcache before
- * the unmapping and tlb after.
- */
-void unmap_kernel_range(unsigned long addr, unsigned long size)
-{
- unsigned long end = addr + size;
-
- flush_cache_vunmap(addr, end);
- unmap_kernel_range_noflush(addr, size);
- flush_tlb_kernel_range(addr, end);
-}
-
static inline void setup_vmalloc_vm_locked(struct vm_struct *vm,
struct vmap_area *va, unsigned long flags, const void *caller)
{
--
2.23.0