Commit dbc2fbd7 authored by Tom Musta's avatar Tom Musta Committed by Benjamin Herrenschmidt
Browse files

powerpc: Fix Unaligned LE Floating Point Loads and Stores 



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: default avatarTom Musta <tmusta@gmail.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 6506b471

arch/powerpc/lib/sstep.c

+40 −12
Original line number Diff line number Diff line
@@ -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;

}