path: root/arch/x86/include
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authorChristoph Hellwig <hch@lst.de>2020-06-25 20:30:40 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-26 00:27:38 -0700
commit800e26b81311dcc0080b8784f80620bb8f2baaa5 (patch)
treebc2e6f37064a2dfd17c1bb9381de8dadb4a2f762 /arch/x86/include
parent0076f029cb2906d32baf3bf4401ef09663071d16 (diff)
x86/hyperv: allocate the hypercall page with only read and execute bits
Patch series "fix a hyperv W^X violation and remove vmalloc_exec" Dexuan reported a W^X violation due to the fact that the hyper hypercall page due switching it to be allocated using vmalloc_exec. The problem is that PAGE_KERNEL_EXEC as used by vmalloc_exec actually sets writable permissions in the pte. This series fixes the issue by switching to the low-level __vmalloc_node_range interface that allows specifing more detailed permissions instead. It then also open codes the other two callers and removes the somewhat confusing vmalloc_exec interface. Peter noted that the hyper hypercall page allocation also has another long standing issue in that it shouldn't use the full vmalloc but just the module space. This issue is so far theoretical as the allocation is done early in the boot process. I plan to fix it with another bigger series for 5.9. This patch (of 3): Avoid a W^X violation cause by the fact that PAGE_KERNEL_EXEC includes the writable bit. For this resurrect the removed PAGE_KERNEL_RX definition, but as PAGE_KERNEL_ROX to match arm64 and powerpc. Link: http://lkml.kernel.org/r/20200618064307.32739-2-hch@lst.de Fixes: 78bb17f76edc ("x86/hyperv: use vmalloc_exec for the hypercall page") Signed-off-by: Christoph Hellwig <hch@lst.de> Reported-by: Dexuan Cui <decui@microsoft.com> Tested-by: Vitaly Kuznetsov <vkuznets@redhat.com> Acked-by: Wei Liu <wei.liu@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Jessica Yu <jeyu@kernel.org> Cc: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/x86/include')
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index 2da1f95b88d7..816b31c68550 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -194,6 +194,7 @@ enum page_cache_mode {
#define _PAGE_TABLE_NOENC (__PP|__RW|_USR|___A| 0|___D| 0| 0)
#define _PAGE_TABLE (__PP|__RW|_USR|___A| 0|___D| 0| 0| _ENC)
#define __PAGE_KERNEL_RO (__PP| 0| 0|___A|__NX|___D| 0|___G)
+#define __PAGE_KERNEL_ROX (__PP| 0| 0|___A| 0|___D| 0|___G)
#define __PAGE_KERNEL_NOCACHE (__PP|__RW| 0|___A|__NX|___D| 0|___G| __NC)
#define __PAGE_KERNEL_VVAR (__PP| 0|_USR|___A|__NX|___D| 0|___G)
#define __PAGE_KERNEL_LARGE (__PP|__RW| 0|___A|__NX|___D|_PSE|___G)
@@ -219,6 +220,7 @@ enum page_cache_mode {
#define PAGE_KERNEL_RO __pgprot_mask(__PAGE_KERNEL_RO | _ENC)
#define PAGE_KERNEL_EXEC __pgprot_mask(__PAGE_KERNEL_EXEC | _ENC)
#define PAGE_KERNEL_EXEC_NOENC __pgprot_mask(__PAGE_KERNEL_EXEC | 0)
+#define PAGE_KERNEL_ROX __pgprot_mask(__PAGE_KERNEL_ROX | _ENC)
#define PAGE_KERNEL_LARGE __pgprot_mask(__PAGE_KERNEL_LARGE | _ENC)