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From: Tom Musta <tommusta@gmail.com>
To: linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Cc: tmusta@gmail.com
Subject: [PATCH 3/3] powerpc: Fix Unaligned LE Floating Point Loads and Stores
Date: Fri, 18 Oct 2013 14:44:17 -0500	[thread overview]
Message-ID: <1382125457.2206.28.camel@tmusta-sc.rchland.ibm.com> (raw)
In-Reply-To: <1382125125.2206.22.camel@tmusta-sc.rchland.ibm.com>

This patch addresses unaligned single precision floating point loads
and stores in the single-step code.  The old implementation
improperly treated an 8 byte structure as an array of two 4 byte
words, which is a classic little endian bug.

Signed-off-by: Tom Musta <tmusta@gmail.com>
---
 arch/powerpc/lib/sstep.c |   52 +++++++++++++++++++++++++++++++++++----------
 1 files changed, 40 insertions(+), 12 deletions(-)

diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index 570f2af..f6f17aa 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -355,22 +355,36 @@ static int __kprobes do_fp_load(int rn, int (*func)(int, unsigned long),
 				struct pt_regs *regs)
 {
 	int err;
-	unsigned long val[sizeof(double) / sizeof(long)];
+	union {
+		double dbl;
+		unsigned long ul[2];
+		struct {
+#ifdef __BIG_ENDIAN__
+			unsigned _pad_;
+			unsigned word;
+#endif
+#ifdef __LITTLE_ENDIAN__
+			unsigned word;
+			unsigned _pad_;
+#endif
+		} single;
+	} data;
 	unsigned long ptr;
 
 	if (!address_ok(regs, ea, nb))
 		return -EFAULT;
 	if ((ea & 3) == 0)
 		return (*func)(rn, ea);
-	ptr = (unsigned long) &val[0];
+	ptr = (unsigned long) &data.ul;
 	if (sizeof(unsigned long) == 8 || nb == 4) {
-		err = read_mem_unaligned(&val[0], ea, nb, regs);
-		ptr += sizeof(unsigned long) - nb;
+		err = read_mem_unaligned(&data.ul[0], ea, nb, regs);
+		if (nb == 4)
+			ptr = (unsigned long)&(data.single.word);
 	} else {
 		/* reading a double on 32-bit */
-		err = read_mem_unaligned(&val[0], ea, 4, regs);
+		err = read_mem_unaligned(&data.ul[0], ea, 4, regs);
 		if (!err)
-			err = read_mem_unaligned(&val[1], ea + 4, 4, regs);
+			err = read_mem_unaligned(&data.ul[1], ea + 4, 4, regs);
 	}
 	if (err)
 		return err;
@@ -382,28 +396,42 @@ static int __kprobes do_fp_store(int rn, int (*func)(int, unsigned long),
 				 struct pt_regs *regs)
 {
 	int err;
-	unsigned long val[sizeof(double) / sizeof(long)];
+	union {
+		double dbl;
+		unsigned long ul[2];
+		struct {
+#ifdef __BIG_ENDIAN__
+			unsigned _pad_;
+			unsigned word;
+#endif
+#ifdef __LITTLE_ENDIAN__
+			unsigned word;
+			unsigned _pad_;
+#endif
+		} single;
+	} data;
 	unsigned long ptr;
 
 	if (!address_ok(regs, ea, nb))
 		return -EFAULT;
 	if ((ea & 3) == 0)
 		return (*func)(rn, ea);
-	ptr = (unsigned long) &val[0];
+	ptr = (unsigned long) &data.ul[0];
 	if (sizeof(unsigned long) == 8 || nb == 4) {
-		ptr += sizeof(unsigned long) - nb;
+		if (nb == 4)
+			ptr = (unsigned long)&(data.single.word);
 		err = (*func)(rn, ptr);
 		if (err)
 			return err;
-		err = write_mem_unaligned(val[0], ea, nb, regs);
+		err = write_mem_unaligned(data.ul[0], ea, nb, regs);
 	} else {
 		/* writing a double on 32-bit */
 		err = (*func)(rn, ptr);
 		if (err)
 			return err;
-		err = write_mem_unaligned(val[0], ea, 4, regs);
+		err = write_mem_unaligned(data.ul[0], ea, 4, regs);
 		if (!err)
-			err = write_mem_unaligned(val[1], ea + 4, 4, regs);
+			err = write_mem_unaligned(data.ul[1], ea + 4, 4, regs);
 	}
 	return err;
 }
-- 
1.7.1

      parent reply	other threads:[~2013-10-18 19:44 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-18 19:38 [PATCH 0/3] powerpc: Fix Little Endian Bugs in Single Step Code Tom Musta
2013-10-18 19:40 ` [PATCH 1/3] powerpc: Enable emulate_step In Little Endian Mode Tom Musta
2013-10-30  0:13   ` Benjamin Herrenschmidt
2013-10-30 17:43   ` Andreas Schwab
2013-10-30 19:35     ` Tom Musta
2013-10-30 19:43       ` Geert Uytterhoeven
2013-10-30 21:45         ` Tom Musta
2013-10-18 19:42 ` [PATCH 2/3] powerpc: Fix Unaligned Loads and Stores Tom Musta
2013-10-18 19:44 ` Tom Musta [this message]

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