Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation this program is
distributed in the hope that it will be useful but without any
warranty without even the implied warranty of merchantability or
fitness for a particular purpose see the gnu general public license
for more details you should have received a copy of the gnu general
public license along with this program if not see http www gnu org
licenses
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 503 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Enrico Weigelt <info@metux.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190602204653.811534538@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add SPDX license identifiers to all Make/Kconfig files which:
- Have no license information of any form
These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:
GPL-2.0-only
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Depending on the size of the area to be memset'ed, the nios2 memset implementation
either uses a naive loop (for buffers smaller or equal than 8 bytes) or a more optimized
implementation (for buffers larger than 8 bytes). This implementation does 4-byte stores
rather than 1-byte stores to speed up memset.
However, we discovered that on our nios2 platform, memset() was not properly setting the
buffer to the expected value. A memset of 0xff would not set the entire buffer to 0xff, but to:
0xff 0x00 0xff 0x00 0xff 0x00 0xff 0x00 ...
Which is obviously incorrect. Our investigation has revealed that the problem lies in the
incorrect constraints used in the inline assembly.
The following piece of assembly, from the nios2 memset implementation, is supposed to
create a 4-byte value that repeats 4 times the 1-byte pattern passed as memset argument:
/* fill8 %3, %5 (c & 0xff) */
" slli %4, %5, 8\n"
" or %4, %4, %5\n"
" slli %3, %4, 16\n"
" or %3, %3, %4\n"
However, depending on the compiler and optimization level, this code might be compiled as:
34: 280a923a slli r5,r5,8
38: 294ab03a or r5,r5,r5
3c: 2808943a slli r4,r5,16
40: 2148b03a or r4,r4,r5
This is wrong because r5 gets used both for %5 and %4, which leads to the final pattern
stored in r4 to be 0xff00ff00 rather than the expected 0xffffffff.
%4 is defined with the "=r" constraint, i.e as an output operand. However, as explained in
http://www.ethernut.de/en/documents/arm-inline-asm.html, this does not prevent gcc from
using the same register for an output operand (%4) and input operand (%5). By using the
constraint modifier '&', we indicate that the register should be used for output only. With this
change, we get the following assembly output:
34: 2810923a slli r8,r5,8
38: 4150b03a or r8,r8,r5
3c: 400e943a slli r7,r8,16
40: 3a0eb03a or r7,r7,r8
Which correctly produces the 0xffffffff pattern when 0xff is passed as the memset() pattern.
It is worth mentioning the observed consequence of this bug: we were hitting the kernel
BUG() in mm/bootmem.c:__free() that verifies when marking a page as free that it was
previously marked as occupied (i.e that the bit was set to 1). The entire bootmem bitmap is
set to 0xff bit via a memset() during the bootmem initialization. The bootmem_free() call right
after the initialization was finding some bits to be set to 0, which didn't make sense since the
bitmap has just been memset'ed to 0xff. Except that due to the bug explained above, the
bitmap was in fact initialized to 0xff00ff00.
Thanks to Marek Vasut for his help and feedback.
Signed-off-by: Romain Perier <romain.perier@free-electrons.com>
Acked-by: Marek Vasut <marex@denx.de>
Acked-by: Ley Foon Tan <lftan@altera.com>
__HAVE_ARCH_MEMMOVE and __HAVE_ARCH_MEMSET are unconditionally defined
for nios2, so there is no need to protect the function definitions of
memmove() and memset().
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Acked-by: Ley Foon Tan <lftan@altera.com>
