Both strncpy and strlcpy suffer from the fact that they do
partial copies of strings into the destination when the target
buffer is too small. This is frequently pointless since an
overflow of the target buffer may make the result invalid.
strncpy() makes it relatively hard to even detect the error
condition, and with strlcpy() you have to duplicate the buffer
size parameter to test to see if the result exceeds it.
By returning zero in the failure case, we both make testing
for it easy, and by simply not copying anything in that case,
we make it mandatory for callers to test the error code.
To catch lazy programmers who don't check, we also place a NUL at
the start of the destination buffer (if there is space) to
ensure that the result is an invalid string.
At some point it may make sense to promote strscpy() to
a global platform-independent function, but other than the
reviewers, no one was interested on LKML, so for now leave
the strscpy() function as file-static.
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Pull Tile arch updates from Chris Metcalf:
"These changes bring in a bunch of new functionality that has been
maintained internally at Tilera over the last year, plus other stray
bits of work that I've taken into the tile tree from other folks.
The changes include some PCI root complex work, interrupt-driven
console support, support for performing fast-path unaligned data
fixups by kernel-based JIT code generation, CONFIG_PREEMPT support,
vDSO support for gettimeofday(), a serial driver for the tilegx
on-chip UART, KGDB support, more optimized string routines, support
for ftrace and kprobes, improved ASLR, and many bug fixes.
We also remove support for the old TILE64 chip, which is no longer
buildable"
* git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile: (85 commits)
tile: refresh tile defconfig files
tile: rework <asm/cmpxchg.h>
tile PCI RC: make default consistent DMA mask 32-bit
tile: add null check for kzalloc in tile/kernel/setup.c
tile: make __write_once a synonym for __read_mostly
tile: remove support for TILE64
tile: use asm-generic/bitops/builtin-*.h
tile: eliminate no-op "noatomichash" boot argument
tile: use standard tile_bundle_bits type in traps.c
tile: simplify code referencing hypervisor API addresses
tile: change <asm/system.h> to <asm/switch_to.h> in comments
tile: mark pcibios_init() as __init
tile: check for correct compiler earlier in asm-offsets.c
tile: use standard 'generic-y' model for <asm/hw_irq.h>
tile: use asm-generic version of <asm/local64.h>
tile PCI RC: add comment about "PCI hole" problem
tile: remove DEBUG_EXTRA_FLAGS kernel config option
tile: add virt_to_kpte() API and clean up and document behavior
tile: support FRAME_POINTER
tile: support reporting Tilera hypervisor statistics
...
The TILE-Gx chip includes an on-chip UART. This change adds support
for using the UART from within the kernel. The UART shim has more
functionality than is exposed here, but to keep the kernel code and
binary simpler, this is a subset of the full API designed to enable
a standard Linux tty serial driver only.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
To support PCIe devices with higher number of MSI-X interrupt vectors,
e.g. 16 for the LSI RAID card, enhance the Gx RC stack to provide more
MSI-X vectors by using the TRIO Scatter Queues, which provide 8 more
vectors in addition to ~10 from the Map Mem regions.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The initial driver support was for a single mPIPE shim on the chip
(as is the case for the Gx36 hardware). The Gx72 chip has two mPIPE
shims, so we extend the driver to handle that case.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This change adds support for accessing the USB shim from within the
kernel. Note that this change by itself does not allow the kernel
to act as a host or as a device; it merely exposes the built-in on-chip
hardware to the kernel.
The <arch/usb_host.h> and <arch/usb_host_def.h> headers are empty at
the moment because the kernel does not require any types or definitions
specific to the tilegx USB shim; the generic USB core code is all we need.
The headers are left in as stubs so that we don't need to modify the
hypervisor header (drv_usb_host_intf.h) from upstream.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Provide kernel support for the tilegx "Transaction I/O" (TRIO) on-chip
hardware. This hardware implements the PCIe interface for tilegx;
the driver changes to use TRIO for PCIe are in a subsequent commit.
The change is layered on top of the tilegx GXIO IORPC subsystem.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
The TILE-Gx chip includes a packet-processing network engine called
mPIPE ("Multicore Programmable Intelligent Packet Engine"). This
change adds support for using the mPIPE engine from within the
kernel. The engine has more functionality than is exposed here,
but to keep the kernel code and binary simpler, this is a subset
of the full API designed to enable standard Linux networking only.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
The dma_queue support is used by both the mPipe (networking)
and Trio (PCI) hardware shims on tilegx. This common code is
selected when either of those drivers is built.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
The GXIO I/O RPC subsystem handles exporting I/O hardware resources to
Linux and to applications running under Linux.
For instance, memory which is made available for I/O DMA must be mapped
by an I/O TLB; that means that such memory must be locked down by Linux,
so that it is not swapped or otherwise reused, as long as those I/O
TLB entries are active. Similarly, configuring direct hardware access
introduces new validation requirements. If a user application registers
memory, Linux must ensure that the supplied virtual addresses are valid,
and turn them into client physical addresses. Similarly, when Linux then
supplies those client physical addresses to the Tilera hypervisor, it
must in turn validate those before turning them into the real physical
addresses which are required by the hardware.
To the extent that these sorts of activities were required on previous
TILE architecture processors, they were implemented in a device-specific
fashion. This meant that every I/O device had its own Tilera hypervisor
driver, its own Linux driver, and in some cases its own user-level
library support. There was a large amount of more-or-less functionally
identical code in different places, particularly in the different Linux
drivers. For TILE-Gx, this support has been generalized into a common
framework, known as the I/O RPC framework or just IORPC.
The two "gxio" directories (one for headers, one for sources) start
with just a few files in each with this infrastructure commit, but
after adding support for the on-board I/O shims for networking, PCI,
USB, crypto, compression, I2CS, etc., there end up being about 20 files
in each directory.
More information on the IORPC framework is in the <hv/iorpc.h> header,
included in this commit.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Chris Metcalf