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authorTom Musta <tommusta@gmail.com>2013-10-18 14:42:08 -0500
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-10-30 16:01:30 +1100
commit6506b4718bb59c5d4e59235b81b5e13ea5d3c49a (patch)
tree24a45ddb2ba911750bf3c2ac9b649560fb65342e
parent630c8a5fc9fb2f3541652b65f23630757d304cc9 (diff)
powerpc: Fix Unaligned Loads and Stores
This patch modifies the unaligned access routines of the sstep.c module so that it properly reverses the bytes of storage operands in the little endian kernel kernel. This is implemented by breaking an unaligned little endian access into a combination of single byte accesses plus an overal byte reversal operation. Signed-off-by: Tom Musta <tmusta@gmail.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
-rw-r--r--arch/powerpc/lib/sstep.c45
1 files changed, 45 insertions, 0 deletions
diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index b1faa1593c90..0121d2140ab9 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -212,11 +212,19 @@ static int __kprobes read_mem_unaligned(unsigned long *dest, unsigned long ea,
{
int err;
unsigned long x, b, c;
+#ifdef __LITTLE_ENDIAN__
+ int len = nb; /* save a copy of the length for byte reversal */
+#endif
/* unaligned, do this in pieces */
x = 0;
for (; nb > 0; nb -= c) {
+#ifdef __LITTLE_ENDIAN__
+ c = 1;
+#endif
+#ifdef __BIG_ENDIAN__
c = max_align(ea);
+#endif
if (c > nb)
c = max_align(nb);
err = read_mem_aligned(&b, ea, c);
@@ -225,7 +233,24 @@ static int __kprobes read_mem_unaligned(unsigned long *dest, unsigned long ea,
x = (x << (8 * c)) + b;
ea += c;
}
+#ifdef __LITTLE_ENDIAN__
+ switch (len) {
+ case 2:
+ *dest = byterev_2(x);
+ break;
+ case 4:
+ *dest = byterev_4(x);
+ break;
+#ifdef __powerpc64__
+ case 8:
+ *dest = byterev_8(x);
+ break;
+#endif
+ }
+#endif
+#ifdef __BIG_ENDIAN__
*dest = x;
+#endif
return 0;
}
@@ -273,9 +298,29 @@ static int __kprobes write_mem_unaligned(unsigned long val, unsigned long ea,
int err;
unsigned long c;
+#ifdef __LITTLE_ENDIAN__
+ switch (nb) {
+ case 2:
+ val = byterev_2(val);
+ break;
+ case 4:
+ val = byterev_4(val);
+ break;
+#ifdef __powerpc64__
+ case 8:
+ val = byterev_8(val);
+ break;
+#endif
+ }
+#endif
/* unaligned or little-endian, do this in pieces */
for (; nb > 0; nb -= c) {
+#ifdef __LITTLE_ENDIAN__
+ c = 1;
+#endif
+#ifdef __BIG_ENDIAN__
c = max_align(ea);
+#endif
if (c > nb)
c = max_align(nb);
err = write_mem_aligned(val >> (nb - c) * 8, ea, c);