[PATCH 1/3] x86/uaccess: Move nmi_uaccess_okay() into uaccess.h

Kees Cook
2022-09-16T14:01:45Z

In preparation for inlining copy_from_user_in_nmi(), move the
nmi_uaccess_okay() declaration into uaccess.h, which makes a bit more
sense anyway. Additionally update all callers to remove the no longer
needed tlbflush.h include, which was only for the declaration of
nmi_uaccess_okay().

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: x86@kernel.org
Cc: linux-perf-users@vger.kernel.org
Cc: bpf@vger.kernel.org
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Yu Zhao <yuzhao@google.com>
Cc: dev@der-flo.net
Signed-off-by: Kees Cook <keescook@chromium.org>
---
arch/x86/events/core.c | 1 -
arch/x86/include/asm/tlbflush.h | 3 ---
arch/x86/include/asm/uaccess.h | 3 +++
arch/x86/lib/usercopy.c | 2 --
include/asm-generic/tlb.h | 9 ---------
include/linux/uaccess.h | 9 +++++++++
kernel/trace/bpf_trace.c | 2 --
7 files changed, 12 insertions(+), 17 deletions(-)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index f969410d0c90..3e2bb6324ca3 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -36,7 +36,6 @@
#include <asm/smp.h>
#include <asm/alternative.h>
#include <asm/mmu_context.h>
-#include <asm/tlbflush.h>
#include <asm/timer.h>
#include <asm/desc.h>
#include <asm/ldt.h>
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index cda3118f3b27..233818bb72c6 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -157,9 +157,6 @@ struct tlb_state_shared {
};
DECLARE_PER_CPU_SHARED_ALIGNED(struct tlb_state_shared, cpu_tlbstate_shared);

-bool nmi_uaccess_okay(void);
-#define nmi_uaccess_okay nmi_uaccess_okay
-
/* Initialize cr4 shadow for this CPU. */
static inline void cr4_init_shadow(void)
{
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 913e593a3b45..e9390eea861b 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -20,6 +20,9 @@ static inline bool pagefault_disabled(void);
# define WARN_ON_IN_IRQ()
#endif

+bool nmi_uaccess_okay(void);
+#define nmi_uaccess_okay nmi_uaccess_okay
+
/**
* access_ok - Checks if a user space pointer is valid
* @addr: User space pointer to start of block to check
diff --git a/arch/x86/lib/usercopy.c b/arch/x86/lib/usercopy.c
index ad0139d25401..959489f2f814 100644
--- a/arch/x86/lib/usercopy.c
+++ b/arch/x86/lib/usercopy.c
@@ -7,8 +7,6 @@
#include <linux/uaccess.h>
#include <linux/export.h>

-#include <asm/tlbflush.h>
-
/**
* copy_from_user_nmi - NMI safe copy from user
* @to: Pointer to the destination buffer
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index 492dce43236e..14efd74f3e70 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -17,15 +17,6 @@
#include <asm/tlbflush.h>
#include <asm/cacheflush.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

/*
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 47e5d374c7eb..065e121d2a86 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -10,6 +10,15 @@

#include <asm/uaccess.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
+
/*
* Architectures should provide two primitives (raw_copy_{to,from}_user())
* and get rid of their private instances of copy_{to,from}_user() and
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 68e5cdd24cef..0fd185c3d174 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -26,8 +26,6 @@
#include <uapi/linux/bpf.h>
#include <uapi/linux/btf.h>

-#include <asm/tlb.h>
-
#include "trace_probe.h"
#include "trace.h"

--
2.34.1