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linux/arch/parisc
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Helge Deller 760dc9f658 parisc: Fix exception handler for fldw and fstw instructions 
commit 7ae1f5508d upstream.

The exception handler is broken for unaligned memory acceses with fldw
and fstw instructions, because it trashes or uses randomly some other
floating point register than the one specified in the instruction word
on loads and stores.

The instruction "fldw 0(addr),%fr22L" (and the other fldw/fstw
instructions) encode the target register (%fr22) in the rightmost 5 bits
of the instruction word. The 7th rightmost bit of the instruction word
defines if the left or right half of %fr22 should be used.

While processing unaligned address accesses, the FR3() define is used to
extract the offset into the local floating-point register set.  But the
calculation in FR3() was buggy, so that for example instead of %fr22,
register %fr12 [((22 * 2) & 0x1f) = 12] was used.

This bug has been since forever in the parisc kernel and I wonder why it
wasn't detected earlier. Interestingly I noticed this bug just because
the libime debian package failed to build on *native* hardware, while it
successfully built in qemu.

This patch corrects the bitshift and masking calculation in FR3().

Signed-off-by: Helge Deller <deller@gmx.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2022-08-31 17:17:59 +02:00
..
boot Kbuild updates for v5.17 2022-01-19 11:15:19 +02:00
configs parisc: Update 32- and 64-bit defconfigs 2022-05-08 20:01:11 +02:00
include parisc/stifb: Fix fb_is_primary_device() only available with CONFIG_FB_STI 2022-06-07 13:01:17 +02:00
kernel parisc: Fix exception handler for fldw and fstw instructions 2022-08-31 17:17:59 +02:00
lib parisc: Use constants to encode the space registers like SR_KERNEL 2022-03-11 19:49:31 +01:00
math-emu parisc: align '*' in comment in math-emu code 2022-06-26 00:19:27 +02:00
mm parisc: Prevent ldil() to sign-extend into upper 32 bits 2022-05-23 13:44:24 +02:00
defpalo.conf parisc: switch to gzip-compressed vmlinuz kernel 2013-07-09 22:09:20 +02:00
install.sh kbuild: factor out the common installation code into scripts/install.sh 2022-05-11 21:45:53 +09:00
Kbuild kbuild: use more subdir- for visiting subdirectories while cleaning 2021-10-24 13:49:46 +09:00
Kconfig parisc: Make CONFIG_64BIT available for ARCH=parisc64 only 2022-08-31 17:17:59 +02:00
Kconfig.debug tracing: Refactor TRACE_IRQFLAGS_SUPPORT in Kconfig 2021-08-16 11:37:21 -04:00
Makefile parisc: remove arch/parisc/nm 2022-05-29 18:39:35 +09:00