[PATCH v3 6/7] mm: Remove vmalloc_sync_(un)mappings()

Joerg Roedel
2020-05-15T14:00:39Z

From: Joerg Roedel <jroedel@suse.de>

These functions are not needed anymore because the vmalloc and ioremap
mappings are now synchronized when they are created or teared down.

Remove all callers and function definitions.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Tested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
---
arch/x86/mm/fault.c | 37 -------------------------------------
drivers/acpi/apei/ghes.c | 6 ------
include/linux/vmalloc.h | 2 --
kernel/notifier.c | 1 -
kernel/trace/trace.c | 12 ------------
mm/nommu.c | 12 ------------
mm/vmalloc.c | 21 ---------------------
7 files changed, 91 deletions(-)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index edeb2adaf31f..255fc631b042 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -214,26 +214,6 @@ void arch_sync_kernel_mappings(unsigned long start, unsigned long end)
}
}

-static void vmalloc_sync(void)
-{
- unsigned long address;
-
- if (SHARED_KERNEL_PMD)
- return;
-
- arch_sync_kernel_mappings(VMALLOC_START, VMALLOC_END);
-}
-
-void vmalloc_sync_mappings(void)
-{
- vmalloc_sync();
-}
-
-void vmalloc_sync_unmappings(void)
-{
- vmalloc_sync();
-}
-
/*
* 32-bit:
*
@@ -336,23 +316,6 @@ static void dump_pagetable(unsigned long address)

#else /* CONFIG_X86_64: */

-void vmalloc_sync_mappings(void)
-{
- /*
- * 64-bit mappings might allocate new p4d/pud pages
- * that need to be propagated to all tasks' PGDs.
- */
- sync_global_pgds(VMALLOC_START & PGDIR_MASK, VMALLOC_END);
-}
-
-void vmalloc_sync_unmappings(void)
-{
- /*
- * Unmappings never allocate or free p4d/pud pages.
- * No work is required here.
- */
-}
-
/*
* 64-bit:
*
diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index 24c9642e8fc7..aabe9c5ee515 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -167,12 +167,6 @@ int ghes_estatus_pool_init(int num_ghes)
if (!addr)
goto err_pool_alloc;

- /*
- * New allocation must be visible in all pgd before it can be found by
- * an NMI allocating from the pool.
- */
- vmalloc_sync_mappings();
-
rc = gen_pool_add(ghes_estatus_pool, addr, PAGE_ALIGN(len), -1);
if (rc)
goto err_pool_add;
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index c80bdb8a6b55..82c9a2ddcfa9 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -141,8 +141,6 @@ extern int remap_vmalloc_range_partial(struct vm_area_struct *vma,

extern int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
unsigned long pgoff);
-void vmalloc_sync_mappings(void);
-void vmalloc_sync_unmappings(void);

/*
* Architectures can set this mask to a combination of PGTBL_P?D_MODIFIED values
diff --git a/kernel/notifier.c b/kernel/notifier.c
index 5989bbb93039..84c987dfbe03 100644
--- a/kernel/notifier.c
+++ b/kernel/notifier.c
@@ -519,7 +519,6 @@ NOKPROBE_SYMBOL(notify_die);

int register_die_notifier(struct notifier_block *nb)
{
- vmalloc_sync_mappings();
return atomic_notifier_chain_register(&die_chain, nb);
}
EXPORT_SYMBOL_GPL(register_die_notifier);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 29615f15a820..f12e99b387b2 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -8527,18 +8527,6 @@ static int allocate_trace_buffers(struct trace_array *tr, int size)
allocate_snapshot = false;
#endif

- /*
- * Because of some magic with the way alloc_percpu() works on
- * x86_64, we need to synchronize the pgd of all the tables,
- * otherwise the trace events that happen in x86_64 page fault
- * handlers can't cope with accessing the chance that a
- * alloc_percpu()'d memory might be touched in the page fault trace
- * event. Oh, and we need to audit all other alloc_percpu() and vmalloc()
- * calls in tracing, because something might get triggered within a
- * page fault trace event!
- */
- vmalloc_sync_mappings();
-
return 0;
}

diff --git a/mm/nommu.c b/mm/nommu.c
index 318df4e236c9..b4267e1471f3 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -369,18 +369,6 @@ void vm_unmap_aliases(void)
}
EXPORT_SYMBOL_GPL(vm_unmap_aliases);

-/*
- * Implement a stub for vmalloc_sync_[un]mapping() if the architecture
- * chose not to have one.
- */
-void __weak vmalloc_sync_mappings(void)
-{
-}
-
-void __weak vmalloc_sync_unmappings(void)
-{
-}
-
struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)
{
BUG();
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 184f5a556cf7..901540e4773b 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1332,12 +1332,6 @@ static bool __purge_vmap_area_lazy(unsigned long start, unsigned long end)
if (unlikely(valist == NULL))
return false;

- /*
- * First make sure the mappings are removed from all page-tables
- * before they are freed.
- */
- vmalloc_sync_unmappings();
-
/*
* TODO: to calculate a flush range without looping.
* The list can be up to lazy_max_pages() elements.
@@ -3177,21 +3171,6 @@ int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
}
EXPORT_SYMBOL(remap_vmalloc_range);

-/*
- * Implement stubs for vmalloc_sync_[un]mappings () if the architecture chose
- * not to have one.
- *
- * The purpose of this function is to make sure the vmalloc area
- * mappings are identical in all page-tables in the system.
- */
-void __weak vmalloc_sync_mappings(void)
-{
-}
-
-void __weak vmalloc_sync_unmappings(void)
-{
-}
-
static int f(pte_t *pte, unsigned long addr, void *data)
{
pte_t ***p = data;
--
2.17.1