Re: Getting weird TPM error after rebasing my tree to security/next-general

[Linus Torvalds]

On Thu, Jan 31, 2019 at 10:52 AM Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> I think what I should do is to just make "memcpy_*io()" do the "align
> naturally" thing.
>
> Let me cook up a patch for you to test.

Does this work for you?

I haven't tested it at all, but I verified that the generated code
seems to make at least some amount of sense.

               Linus
 arch/x86/lib/iomem.c | 27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/arch/x86/lib/iomem.c b/arch/x86/lib/iomem.c
index 66894675f3c8..7b5b07f3d370 100644
--- a/arch/x86/lib/iomem.c
+++ b/arch/x86/lib/iomem.c
@@ -3,7 +3,7 @@
 #include <linux/io.h>
 
 /* Originally from i386/string.h */
-static __always_inline void __iomem_memcpy(void *to, const void *from, size_t n)
+static __always_inline void rep_movs(void *to, const void *from, size_t n)
 {
 	unsigned long d0, d1, d2;
 	asm volatile("rep ; movsl\n\t"
@@ -19,15 +19,36 @@ static __always_inline void __iomem_memcpy(void *to, const void *from, size_t n)
 		     : "memory");
 }
 
+#define movs(type,to,from) \
+	asm volatile("movs" type:"=&D" (to), "=&S" (from):"0" (to), "1" (from):"memory")
+
 void memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
 {
-	__iomem_memcpy(to, (const void *)from, n);
+	/* Unaligned IO? */
+	if (n && unlikely(1 & (unsigned long)from)) {
+		movs("b", to, from);
+		n--;
+	}
+	if (n > 1 && unlikely(2 & (unsigned long)from)) {
+		movs("w", to, from);
+		n-=2;
+	}
+	rep_movs(to, (const void *)from, n);
 }
 EXPORT_SYMBOL(memcpy_fromio);
 
 void memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
 {
-	__iomem_memcpy((void *)to, (const void *) from, n);
+	/* Unaligned IO? */
+	if (n && unlikely(1 & (unsigned long)to)) {
+		movs("b", to, from);
+		n--;
+	}
+	if (n > 1 && unlikely(2 & (unsigned long)to)) {
+		movs("w", to, from);
+		n-=2;
+	}
+	rep_movs((void *)to, (const void *) from, n);
 }
 EXPORT_SYMBOL(memcpy_toio);