The following commit has been merged into the x86/pasid branch of tip:
Commit-ID: 0888e1030d3e3e5ce9dfd8e030cf13a2e9a1519a
Gitweb: https://git.kernel.org/tip/0888e1030d3e3e5ce9dfd8e030cf13a2e9a1519a
Author: Dave Jiang <dave.jiang@xxxxxxxxx>
AuthorDate: Mon, 05 Oct 2020 08:11:22 -07:00
Committer: Borislav Petkov <bp@xxxxxxx>
CommitterDate: Wed, 07 Oct 2020 17:49:25 +02:00
x86/asm: Carve out a generic movdir64b() helper for general usage
Carve out the MOVDIR64B inline asm primitive into a generic helper so
that it can be used by other functions. Move it to special_insns.h and
have iosubmit_cmds512() call it.
[ bp: Massage commit message. ]
Suggested-by: Michael Matz <matz@xxxxxxx>
Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Reviewed-by: Tony Luck <tony.luck@xxxxxxxxx>
Reviewed-by: Borislav Petkov <bp@xxxxxxx>
Link: https://lkml.kernel.org/r/20201005151126.657029-2-dave.jiang@xxxxxxxxx
---
arch/x86/include/asm/io.h | 17 +++--------------
arch/x86/include/asm/special_insns.h | 22 ++++++++++++++++++++++
2 files changed, 25 insertions(+), 14 deletions(-)
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index e1aa17a..d726459 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -401,7 +401,7 @@ extern bool phys_mem_access_encrypted(unsigned long phys_addr,
/**
* iosubmit_cmds512 - copy data to single MMIO location, in 512-bit units
- * @__dst: destination, in MMIO space (must be 512-bit aligned)
+ * @dst: destination, in MMIO space (must be 512-bit aligned)
* @src: source
* @count: number of 512 bits quantities to submit
*
@@ -412,25 +412,14 @@ extern bool phys_mem_access_encrypted(unsigned long phys_addr,
* Warning: Do not use this helper unless your driver has checked that the CPU
* instruction is supported on the platform.
*/
-static inline void iosubmit_cmds512(void __iomem *__dst, const void *src,
+static inline void iosubmit_cmds512(void __iomem *dst, const void *src,
size_t count)
{
- /*
- * Note that this isn't an "on-stack copy", just definition of "dst"
- * as a pointer to 64-bytes of stuff that is going to be overwritten.
- * In the MOVDIR64B case that may be needed as you can use the
- * MOVDIR64B instruction to copy arbitrary memory around. This trick
- * lets the compiler know how much gets clobbered.
- */
- volatile struct { char _[64]; } *dst = __dst;
const u8 *from = src;
const u8 *end = from + count * 64;
while (from < end) {
- /* MOVDIR64B [rdx], rax */
- asm volatile(".byte 0x66, 0x0f, 0x38, 0xf8, 0x02"
- : "=m" (dst)
- : "d" (from), "a" (dst));
+ movdir64b(dst, from);
from += 64;
}
}
diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h
index 59a3e13..d4baa0e 100644
--- a/arch/x86/include/asm/special_insns.h
+++ b/arch/x86/include/asm/special_insns.h
@@ -234,6 +234,28 @@ static inline void clwb(volatile void *__p)
#define nop() asm volatile ("nop")
+/* The dst parameter must be 64-bytes aligned */
+static inline void movdir64b(void *dst, const void *src)
+{
+ const struct { char _[64]; } *__src = src;
+ struct { char _[64]; } *__dst = dst;
+
+ /*
+ * MOVDIR64B %(rdx), rax.
+ *
+ * Both __src and __dst must be memory constraints in order to tell the
+ * compiler that no other memory accesses should be reordered around
+ * this one.
+ *
+ * Also, both must be supplied as lvalues because this tells
+ * the compiler what the object is (its size) the instruction accesses.
+ * I.e., not the pointers but what they point to, thus the deref'ing '*'.
+ */
+ asm volatile(".byte 0x66, 0x0f, 0x38, 0xf8, 0x02"
+ : "+m" (*__dst)
+ : "m" (*__src), "a" (__dst), "d" (__src));
+}
+
#endif /* __KERNEL__ */
#endif /* _ASM_X86_SPECIAL_INSNS_H */
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