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authorNadav Amit <namit@vmware.com>2019-04-25 17:11:42 -0700
committerIngo Molnar <mingo@kernel.org>2019-04-30 12:37:48 +0200
commit5932c9fd19e6e5ac84756c5c32fe5155d9a6b458 (patch)
treeb20b7288dfba103ee9ac7ea05d3f066a0aad3139 /include/asm-generic
parente836673c9b4966bc78e38aeda25f7022c57f0e90 (diff)
downloadlinux-5932c9fd19e6e5ac84756c5c32fe5155d9a6b458.tar.bz2
mm/tlb: Provide default nmi_uaccess_okay()
x86 has an nmi_uaccess_okay(), but other architectures do not. Arch-independent code might need to know whether access to user addresses is ok in an NMI context or in other code whose execution context is unknown. Specifically, this function is needed for bpf_probe_write_user(). Add a default implementation of nmi_uaccess_okay() for architectures that do not have such a function. Signed-off-by: Nadav Amit <namit@vmware.com> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: <akpm@linux-foundation.org> Cc: <ard.biesheuvel@linaro.org> Cc: <deneen.t.dock@intel.com> Cc: <kernel-hardening@lists.openwall.com> Cc: <kristen@linux.intel.com> Cc: <linux_dti@icloud.com> Cc: <will.deacon@arm.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Rik van Riel <riel@surriel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20190426001143.4983-23-namit@vmware.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/asm-generic')
-rw-r--r--include/asm-generic/tlb.h9
1 files changed, 9 insertions, 0 deletions
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index 6be86c1c5c58..075b353cae86 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -20,6 +20,15 @@
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
+/*
+ * Blindly accessing user memory from NMI context can be dangerous
+ * if we're in the middle of switching the current user task or switching
+ * the loaded mm.
+ */
+#ifndef nmi_uaccess_okay
+# define nmi_uaccess_okay() true
+#endif
+
#ifdef CONFIG_MMU
#ifdef CONFIG_HAVE_RCU_TABLE_FREE