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um: support some of ARCH_HAS_SET_MEMORY

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For now, only support set_memory_ro()/rw() which we need for
the stack protection in the next patch.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Johannes Berg 2020-12-05 21:50:17 +01:00 committed by Richard Weinberger
parent 58b09f6869
commit 963285b0b4
4 changed files with 59 additions and 0 deletions
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1
arch/um/Kconfig
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@ -15,6 +15,7 @@ config UML
select HAVE_DEBUG_KMEMLEAK
select HAVE_DEBUG_BUGVERBOSE
select NO_DMA
select ARCH_HAS_SET_MEMORY
select GENERIC_IRQ_SHOW
select GENERIC_CPU_DEVICES
select GENERIC_CLOCKEVENTS

3
arch/um/include/asm/pgtable.h
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@ -55,12 +55,15 @@ extern unsigned long end_iomem;
#define _PAGE_CHG_MASK (PAGE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY)
#define __PAGE_KERNEL_EXEC \
(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY | _PAGE_ACCESSED)
#define __PAGE_KERNEL_RO \
(_PAGE_PRESENT | _PAGE_DIRTY | _PAGE_ACCESSED)
#define PAGE_NONE __pgprot(_PAGE_PROTNONE | _PAGE_ACCESSED)
#define PAGE_SHARED __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | _PAGE_ACCESSED)
#define PAGE_COPY __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_ACCESSED)
#define PAGE_READONLY __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_ACCESSED)
#define PAGE_KERNEL __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY | _PAGE_ACCESSED)
#define PAGE_KERNEL_EXEC __pgprot(__PAGE_KERNEL_EXEC)
#define PAGE_KERNEL_RO __pgprot(__PAGE_KERNEL_RO)
/*
* The i386 can't do page protection for execute, and considers that the same

1
arch/um/include/asm/set_memory.h Normal file
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@ -0,0 +1 @@
#include <asm-generic/set_memory.h>

54
arch/um/kernel/tlb.c
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@ -608,3 +608,57 @@ void force_flush_all(void)
vma = vma->vm_next;
}
}
struct page_change_data {
unsigned int set_mask, clear_mask;
};
static int change_page_range(pte_t *ptep, unsigned long addr, void *data)
{
struct page_change_data *cdata = data;
pte_t pte = READ_ONCE(*ptep);
pte_clear_bits(pte, cdata->clear_mask);
pte_set_bits(pte, cdata->set_mask);
set_pte(ptep, pte);
return 0;
}
static int change_memory(unsigned long start, unsigned long pages,
unsigned int set_mask, unsigned int clear_mask)
{
unsigned long size = pages * PAGE_SIZE;
struct page_change_data data;
int ret;
data.set_mask = set_mask;
data.clear_mask = clear_mask;
ret = apply_to_page_range(&init_mm, start, size, change_page_range,
&data);
flush_tlb_kernel_range(start, start + size);
return ret;
}
int set_memory_ro(unsigned long addr, int numpages)
{
return change_memory(addr, numpages, 0, _PAGE_RW);
}
int set_memory_rw(unsigned long addr, int numpages)
{
return change_memory(addr, numpages, _PAGE_RW, 0);
}
int set_memory_nx(unsigned long addr, int numpages)
{
return -EOPNOTSUPP;
}
int set_memory_x(unsigned long addr, int numpages)
{
return -EOPNOTSUPP;
}