Reviewing Tobin's patches for getting pointers out early before
entropy has been established, I noticed that there's a lone smp_mb() in
the code. As with most lone memory barriers, this one appears to be
incorrectly used.
We currently basically have this:
get_random_bytes(&ptr_key, sizeof(ptr_key));
/*
* have_filled_random_ptr_key==true is dependent on get_random_bytes().
* ptr_to_id() needs to see have_filled_random_ptr_key==true
* after get_random_bytes() returns.
*/
smp_mb();
WRITE_ONCE(have_filled_random_ptr_key, true);
And later we have:
if (unlikely(!have_filled_random_ptr_key))
return string(buf, end, "(ptrval)", spec);
/* Missing memory barrier here. */
hashval = (unsigned long)siphash_1u64((u64)ptr, &ptr_key);
As the CPU can perform speculative loads, we could have a situation
with the following:
CPU0 CPU1
---- ----
load ptr_key = 0
store ptr_key = random
smp_mb()
store have_filled_random_ptr_key
load have_filled_random_ptr_key = true
BAD BAD BAD! (you're so bad!)
Because nothing prevents CPU1 from loading ptr_key before loading
have_filled_random_ptr_key.
But this race is very unlikely, but we can't keep an incorrect smp_mb() in
place. Instead, replace the have_filled_random_ptr_key with a static_branch
not_filled_random_ptr_key, that is initialized to true and changed to false
when we get enough entropy. If the update happens in early boot, the
static_key is updated immediately, otherwise it will have to wait till
entropy is filled and this happens in an interrupt handler which can't
enable a static_key, as that requires a preemptible context. In that case, a
work_queue is used to enable it, as entropy already took too long to
establish in the first place waiting a little more shouldn't hurt anything.
The benefit of using the static key is that the unlikely branch in
vsprintf() now becomes a nop.
Link: http://lkml.kernel.org/r/20180515100558.21df515e@gandalf.local.home
Cc: stable@vger.kernel.org
Fixes: ad67b74d24 ("printk: hash addresses printed with %p")
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
seq_put_decimal_ull_w(m, str, val, width) prints a decimal number with a
specified minimal field width.
It is equivalent of seq_printf(m, "%s%*d", str, width, val), but it
works much faster.
== test_smaps.py
num = 0
with open("/proc/1/smaps") as f:
for x in xrange(10000):
data = f.read()
f.seek(0, 0)
==
== Before patch ==
$ time python test_smaps.py
real 0m4.593s
user 0m0.398s
sys 0m4.158s
== After patch ==
$ time python test_smaps.py
real 0m3.828s
user 0m0.413s
sys 0m3.408s
$ perf -g record python test_smaps.py
== Before patch ==
- 79.01% 3.36% python [kernel.kallsyms] [k] show_smap.isra.33
- 75.65% show_smap.isra.33
+ 48.85% seq_printf
+ 15.75% __walk_page_range
+ 9.70% show_map_vma.isra.23
0.61% seq_puts
== After patch ==
- 75.51% 4.62% python [kernel.kallsyms] [k] show_smap.isra.33
- 70.88% show_smap.isra.33
+ 24.82% seq_put_decimal_ull_w
+ 19.78% __walk_page_range
+ 12.74% seq_printf
+ 11.08% show_map_vma.isra.23
+ 1.68% seq_puts
[akpm@linux-foundation.org: fix drivers/of/unittest.c build]
Link: http://lkml.kernel.org/r/20180212074931.7227-1-avagin@openvz.org
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 841a915d20 ("printf: Do not have bprintf dereference pointers")
would preprocess various pointers that are dereferenced in the bprintf()
because the recording and printing are done at two different times. Some
pointers stayed dereferenced in the ring buffer because user space could
handle them (namely "%pS" and friends). Pointers that are not dereferenced
should not be processed immediately but instead just saved directly.
Cc: stable@vger.kernel.org
Fixes: 841a915d20 ("printf: Do not have bprintf dereference pointers")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Like %pK already does, print "00000000" instead.
This confused people -- the convention is that "(null)" means you tried to
dereference a null pointer as opposed to printing the address.
Link: http://lkml.kernel.org/r/20180204174521.21383-1-kilobyte@angband.pl
To: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Joe Perches <joe@perches.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: "Roberts, William C" <william.c.roberts@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Adam Borowski <kilobyte@angband.pl>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Pull printk updates from Petr Mladek:
- Add a console_msg_format command line option:
The value "default" keeps the old "[time stamp] text\n" format. The
value "syslog" allows to see the syslog-like "<log
level>[timestamp] text" format.
This feature was requested by people doing regression tests, for
example, 0day robot. They want to have both filtered and full logs
at hands.
- Reduce the risk of softlockup:
Pass the console owner in a busy loop.
This is a new approach to the old problem. It was first proposed by
Steven Rostedt on Kernel Summit 2017. It marks a context in which
the console_lock owner calls console drivers and could not sleep.
On the other side, printk() callers could detect this state and use
a busy wait instead of a simple console_trylock(). Finally, the
console_lock owner checks if there is a busy waiter at the end of
the special context and eventually passes the console_lock to the
waiter.
The hand-off works surprisingly well and helps in many situations.
Well, there is still a possibility of the softlockup, for example,
when the flood of messages stops and the last owner still has too
much to flush.
There is increasing number of people having problems with
printk-related softlockups. We might eventually need to get better
solution. Anyway, this looks like a good start and promising
direction.
- Do not allow to schedule in console_unlock() called from printk():
This reverts an older controversial commit. The reschedule helped
to avoid softlockups. But it also slowed down the console output.
This patch is obsoleted by the new console waiter logic described
above. In fact, the reschedule made the hand-off less effective.
- Deprecate "%pf" and "%pF" format specifier:
It was needed on ia64, ppc64 and parisc64 to dereference function
descriptors and show the real function address. It is done
transparently by "%ps" and "pS" format specifier now.
Sergey Senozhatsky found that all the function descriptors were in
a special elf section and could be easily detected.
- Remove printk_symbol() API:
It has been obsoleted by "%pS" format specifier, and this change
helped to remove few continuous lines and a less intuitive old API.
- Remove redundant memsets:
Sergey removed unnecessary memset when processing printk.devkmsg
command line option.
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk: (27 commits)
printk: drop redundant devkmsg_log_str memsets
printk: Never set console_may_schedule in console_trylock()
printk: Hide console waiter logic into helpers
printk: Add console owner and waiter logic to load balance console writes
kallsyms: remove print_symbol() function
checkpatch: add pF/pf deprecation warning
symbol lookup: introduce dereference_symbol_descriptor()
parisc64: Add .opd based function descriptor dereference
powerpc64: Add .opd based function descriptor dereference
ia64: Add .opd based function descriptor dereference
sections: split dereference_function_descriptor()
openrisc: Fix conflicting types for _exext and _stext
lib: do not use print_symbol()
irq debug: do not use print_symbol()
sysfs: do not use print_symbol()
drivers: do not use print_symbol()
x86: do not use print_symbol()
unicore32: do not use print_symbol()
sh: do not use print_symbol()
mn10300: do not use print_symbol()
...
There's not much changes for the tracing system this release.
Mostly small clean ups and fixes.
The biggest change is to how bprintf works. bprintf is used by
trace_printk() to just save the format and args of a printf call,
and the formatting is done when the trace buffer is read. This is
done to keep the formatting out of the fast path (this was recommended
by you). The issue is when arguments are de-referenced.
If a pointer is saved, and the format has something like "%*pbl",
when the buffer is read, it will de-reference the argument then.
The problem is if the data no longer exists. This can cause the
kernel to oops.
The fix for this was to make these de-reference pointes do
the formatting at the time it is called (the fast path), as
this guarantees that the data exists (and doesn't change later)
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Merge tag 'trace-v4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
"There's not much changes for the tracing system this release. Mostly
small clean ups and fixes.
The biggest change is to how bprintf works. bprintf is used by
trace_printk() to just save the format and args of a printf call, and
the formatting is done when the trace buffer is read. This is done to
keep the formatting out of the fast path (this was recommended by
you). The issue is when arguments are de-referenced.
If a pointer is saved, and the format has something like "%*pbl", when
the buffer is read, it will de-reference the argument then. The
problem is if the data no longer exists. This can cause the kernel to
oops.
The fix for this was to make these de-reference pointes do the
formatting at the time it is called (the fast path), as this
guarantees that the data exists (and doesn't change later)"
* tag 'trace-v4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
vsprintf: Do not have bprintf dereference pointers
ftrace: Mark function tracer test functions noinline/noclone
trace_uprobe: Display correct offset in uprobe_events
tracing: Make sure the parsed string always terminates with '\0'
tracing: Clear parser->idx if only spaces are read
tracing: Detect the string nul character when parsing user input string
When trace_printk() was introduced, it was discussed that making it be as
low overhead as possible, that the processing of the format string should be
delayed until it is read. That is, a "trace_printk()" should not convert
the %d into numbers and so on, but instead, save the fmt string and all the
args in the buffer at the time of recording. When the trace_printk() data is
read, it would then parse the format string and do the conversions of the
saved arguments in the tracing buffer.
The code to perform this was added to vsprintf where vbin_printf() would
save the arguments of a specified format string in a buffer, then
bstr_printf() could be used to convert the buffer with the same format
string into the final output, as if vsprintf() was called in one go.
The issue arises when dereferenced pointers are used. The problem is that
something like %*pbl which reads a bitmask, will save the pointer to the
bitmask in the buffer. Then the reading of the buffer via bstr_printf() will
then look at the pointer to process the final output. Obviously the value of
that pointer could have changed since the time it was recorded to the time
the buffer is read. Worse yet, the bitmask could be unmapped, and the
reading of the trace buffer could actually cause a kernel oops.
Another problem is that user space tools such as perf and trace-cmd do not
have access to the contents of these pointers, and they become useless when
the tracing buffer is extracted.
Instead of having vbin_printf() simply save the pointer in the buffer for
later processing, have it perform the formatting at the time bin_printf() is
called. This will fix the issue of dereferencing pointers at a later time,
and has the extra benefit of having user space tools understand these
values.
Since perf and trace-cmd already can handle %p[sSfF] via saving kallsyms,
their pointers are saved and not processed during vbin_printf(). If they
were converted, it would break perf and trace-cmd, as they would not know
how to deal with the conversion.
Link: http://lkml.kernel.org/r/20171228204025.14a71d8f@gandalf.local.home
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
dereference_symbol_descriptor() invokes appropriate ARCH specific
function descriptor dereference callbacks:
- dereference_kernel_function_descriptor() if the pointer is a
kernel symbol;
- dereference_module_function_descriptor() if the pointer is a
module symbol.
This is the last step needed to make '%pS/%ps' smart enough to
handle function descriptor dereference on affected ARCHs and
to retire '%pF/%pf'.
To refresh it:
Some architectures (ia64, ppc64, parisc64) use an indirect pointer
for C function pointers - the function pointer points to a function
descriptor and we need to dereference it to get the actual function
pointer.
Function descriptors live in .opd elf section and all affected
ARCHs (ia64, ppc64, parisc64) handle it properly for kernel and
modules. So we, technically, can decide if the dereference is
needed by simply looking at the pointer: if it belongs to .opd
section then we need to dereference it.
The kernel and modules have their own .opd sections, obviously,
that's why we need to split dereference_function_descriptor()
and use separate kernel and module dereference arch callbacks.
Link: http://lkml.kernel.org/r/20171206043649.GB15885@jagdpanzerIV
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: James Bottomley <jejb@parisc-linux.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-ia64@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Tested-by: Tony Luck <tony.luck@intel.com> #ia64
Tested-by: Santosh Sivaraj <santosh@fossix.org> #powerpc
Tested-by: Helge Deller <deller@gmx.de> #parisc64
Signed-off-by: Petr Mladek <pmladek@suse.com>
Documentation/printk-formats.txt is a candidate for conversion to
ReStructuredText format. Some effort has already been made to do this
conversion even thought the suffix is currently .txt
Changes required to complete conversion
- Move printk-formats.txt to core-api/printk-formats.rst
- Add entry to Documentation/core-api/index.rst
- Remove entry from Documentation/00-INDEX
- Fix minor grammatical errors.
- Order heading adornments as suggested by rst docs.
- Use 'Passed by reference' uniformly.
- Update pointer documentation around %px specifier.
- Fix erroneous double backticks (to commas).
- Remove extraneous double backticks (suggested by Jonathan Corbet).
- Simplify documentation for kobject.
Signed-off-by: Tobin C. Harding <me@tobin.cc>
[jc: downcased "kernel"]
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Instead, just fall back on the new '%p' behavior which hashes the
pointer.
Otherwise, '%pK' - that was intended to mark a pointer as restricted -
just ends up leaking pointers that a normal '%p' wouldn't leak. Which
just make the whole thing pointless.
I suspect we should actually get rid of '%pK' entirely, and make it just
work as '%p' regardless, but this is the minimal obvious fix. People
who actually use 'kptr_restrict' should weigh in on which behavior they
want.
Cc: Tobin Harding <me@tobin.cc>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
printk specifier %p now hashes all addresses before printing. Sometimes
we need to see the actual unmodified address. This can be achieved using
%lx but then we face the risk that if in future we want to change the
way the Kernel handles printing of pointers we will have to grep through
the already existent 50 000 %lx call sites. Let's add specifier %px as a
clear, opt-in, way to print a pointer and maintain some level of
isolation from all the other hex integer output within the Kernel.
Add printk specifier %px to print the actual unmodified address.
Signed-off-by: Tobin C. Harding <me@tobin.cc>
Currently there exist approximately 14 000 places in the kernel where
addresses are being printed using an unadorned %p. This potentially
leaks sensitive information regarding the Kernel layout in memory. Many
of these calls are stale, instead of fixing every call lets hash the
address by default before printing. This will of course break some
users, forcing code printing needed addresses to be updated.
Code that _really_ needs the address will soon be able to use the new
printk specifier %px to print the address.
For what it's worth, usage of unadorned %p can be broken down as
follows (thanks to Joe Perches).
$ git grep -E '%p[^A-Za-z0-9]' | cut -f1 -d"/" | sort | uniq -c
1084 arch
20 block
10 crypto
32 Documentation
8121 drivers
1221 fs
143 include
101 kernel
69 lib
100 mm
1510 net
40 samples
7 scripts
11 security
166 sound
152 tools
2 virt
Add function ptr_to_id() to map an address to a 32 bit unique
identifier. Hash any unadorned usage of specifier %p and any malformed
specifiers.
Signed-off-by: Tobin C. Harding <me@tobin.cc>
Currently code to handle %pK is all within the switch statement in
pointer(). This is the wrong level of abstraction. Each of the other switch
clauses call a helper function, pK should do the same.
Refactor code out of pointer() to new function restricted_pointer().
Signed-off-by: Tobin C. Harding <me@tobin.cc>
Please do not apply this to mainline directly, instead please re-run the
coccinelle script shown below and apply its output.
For several reasons, it is desirable to use {READ,WRITE}_ONCE() in
preference to ACCESS_ONCE(), and new code is expected to use one of the
former. So far, there's been no reason to change most existing uses of
ACCESS_ONCE(), as these aren't harmful, and changing them results in
churn.
However, for some features, the read/write distinction is critical to
correct operation. To distinguish these cases, separate read/write
accessors must be used. This patch migrates (most) remaining
ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following
coccinelle script:
----
// Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and
// WRITE_ONCE()
// $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch
virtual patch
@ depends on patch @
expression E1, E2;
@@
- ACCESS_ONCE(E1) = E2
+ WRITE_ONCE(E1, E2)
@ depends on patch @
expression E;
@@
- ACCESS_ONCE(E)
+ READ_ONCE(E)
----
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: davem@davemloft.net
Cc: linux-arch@vger.kernel.org
Cc: mpe@ellerman.id.au
Cc: shuah@kernel.org
Cc: snitzer@redhat.com
Cc: thor.thayer@linux.intel.com
Cc: tj@kernel.org
Cc: viro@zeniv.linux.org.uk
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
- vsprintf format specifier %pOF for device_node's. This will enable us
to stop storing the full node names. Conversion of users will happen
next cycle.
- Update documentation to point to DT specification instead of ePAPR.
- Split out graph and property functions to a separate file.
- New of-graph functions for ALSA
- Add vendor prefixes for RISC-V, Linksys, iWave Systems, Roofull,
Itead, and BananaPi.
- Improve dtx_diff utility filename printing.
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Merge tag 'devicetree-for-4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux
Pull DeviceTree updates from Rob Herring:
- vsprintf format specifier %pOF for device_node's. This will enable us
to stop storing the full node names. Conversion of users will happen
next cycle.
- Update documentation to point to DT specification instead of ePAPR.
- Split out graph and property functions to a separate file.
- New of-graph functions for ALSA
- Add vendor prefixes for RISC-V, Linksys, iWave Systems, Roofull,
Itead, and BananaPi.
- Improve dtx_diff utility filename printing.
* tag 'devicetree-for-4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux: (32 commits)
of: document /sys/firmware/fdt
dt-bindings: Add RISC-V vendor prefix
vsprintf: Add %p extension "%pOF" for device tree
of: find_node_by_full_name rewrite to compare each level
of: use kbasename instead of open coding
dt-bindings: thermal: add file extension to brcm,ns-thermal
of: update ePAPR references to point to Devicetree Specification
scripts/dtc: dtx_diff - Show real file names in diff header
of: detect invalid phandle in overlay
of: be consistent in form of file mode
of: make __of_attach_node() static
of: address.c header comment typo
of: fdt.c header comment typo
of: make of_fdt_is_compatible() static
dt-bindings: display-timing.txt convert non-ascii characters to ascii
Documentation: remove overlay-notes reference to non-existent file
dt-bindings: usb: exynos-usb: Add missing required VDD properties
dt-bindings: Add vendor prefix for Linksys
MAINTAINERS: add device tree ABI documentation file
of: Add vendor prefix for iWave Systems Technologies Pvt. Ltd
...
90% of the usage of device node's full_name is printing it out in a
kernel message. However, storing the full path for every node is
wasteful and redundant. With a custom format specifier, we can generate
the full path at run-time and eventually remove the full path from every
node.
For instance typical use is:
pr_info("Frobbing node %s\n", node->full_name);
Which can be written now as:
pr_info("Frobbing node %pOF\n", node);
'%pO' is the base specifier to represent kobjects with '%pOF'
representing struct device_node. Currently, struct device_node is the
only supported type of kobject.
More fine-grained control of formatting includes printing the name,
flags, path-spec name and others, explained in the documentation entry.
Originally written by Pantelis, but pretty much rewrote the core
function using existing string/number functions. The 2 passes were
unnecessary and have been removed. Also, updated the checkpatch.pl
check. The unittest code was written by Grant Likely.
Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
Acked-by: Joe Perches <joe@perches.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Our "little endian" UUID really is a Wintel GUID, so rename it and its
helpers such (guid_t). The big endian UUID is the only true one, so
give it the name uuid_t. The uuid_le and uuid_be names are retained for
now, but will hopefully go away soon. The exception to that are the _cmp
helpers that will be replaced by better primitives ASAP and thus don't
get the new names.
Also the _to_bin helpers are named to match the better named uuid_parse
routine in userspace.
Also remove the existing typedef in XFS that's now been superceeded by
the generic type name.
Signed-off-by: Christoph Hellwig <hch@lst.de>
[andy: also update the UUID_LE/UUID_BE macros including fallout]
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
%pK was at least once misused at %pk in an out-of-tree module. This
lead to some security concerns. Add the ability to track single and
multiple line statements for misuses of %p<foo>.
[akpm@linux-foundation.org: add helpful comment into lib/vsprintf.c]
[akpm@linux-foundation.org: text tweak]
Link: http://lkml.kernel.org/r/163a690510e636a23187c0dc9caa09ddac6d4cde.1488228427.git.joe@perches.com
Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: William Roberts <william.c.roberts@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The vsnprintf() kernel-doc comment uses % character with a special
meaning other than escaping a constant. As ReST already defines
``literal`` as an escape sequence, let's make kernel-doc handle it,
and use it at lib/vsprintf.c.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Now that %z is standartised in C99 there is no reason to support %Z.
Unlike %L it doesn't even make format strings smaller.
Use BUILD_BUG_ON in a couple ATM drivers.
In case anyone didn't notice lib/vsprintf.o is about half of SLUB which
is in my opinion is quite an achievement. Hopefully this patch inspires
someone else to trim vsprintf.c more.
Link: http://lkml.kernel.org/r/20170103230126.GA30170@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are new helpers in this patch:
uuid_is_valid checks if a UUID is valid
uuid_be_to_bin converts from string to binary (big endian)
uuid_le_to_bin converts from string to binary (little endian)
They will be used in future, i.e. in the following patches in the series.
This also moves the indices arrays to lib/uuid.c to be shared accross
modules.
[andriy.shevchenko@linux.intel.com: fix typo]
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are few functions here and there along with type definitions that
provide UUID API. This series consolidates everything under one hood
and converts current users.
This has been tested for a while internally, however it doesn't mean we
covered all possible cases (especially accuracy of UUID constants after
conversion). So, please test this as much as you can and provide your
tag. We appreciate the effort.
The ACPI conversion is postponed for now to sort more generic things out
first.
This patch (of 9):
Since we have hex_byte_pack_upper() we may use it directly and avoid
second loop.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Implement basic character sets for the '%[' conversion specifier.
The '%[' conversion specifier matches a nonempty sequence of characters
from the specified set of accepted (or with '^', rejected) characters
between the brackets. The substring matched is to be made up of
characters in (or not in) the set. This is useful for matching
substrings that are delimited by something other than spaces.
This implementation differs from its glibc counterpart in the following ways:
(1) No support for character ranges (e.g., 'a-z' or '0-9')
(2) The hyphen '-' is not a special character
(3) The closing bracket ']' cannot be matched
(4) No support (yet) for discarding matching input ('%*[')
The bitmap code is largely based upon sample code which was provided by
Rasmus.
The motivation for adding character set support to sscanf originally
stemmed from the kernel livepatching project. An ongoing patchset
utilizes new livepatch Elf symbol and section names to store important
metadata livepatch needs to properly apply its patches. Such metadata
is stored in these section and symbol names as substrings delimited by
periods '.' and commas ','. For example, a livepatch symbol name might
look like this:
.klp.sym.vmlinux.printk,0
However, sscanf currently can only extract "substrings" delimited by
whitespace using the "%s" specifier. Thus for the above symbol name,
one cannot not use sscanf() to extract substrings "vmlinux" or
"printk", for example. A number of discussions on the livepatch
mailing list dealing with string parsing code for extracting these '.'
and ',' delimited substrings eventually led to the conclusion that such
code would be completely unnecessary if the kernel sscanf() supported
character sets. Thus only a single sscanf() call would be necessary to
extract these substrings. In addition, such an addition to sscanf()
could benefit other areas of the kernel that might have a similar need
in the future.
[akpm@linux-foundation.org: 80-col tweaks]
Signed-off-by: Jessica Yu <jeyu@redhat.com>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In mm we use several kinds of flags bitfields that are sometimes printed
for debugging purposes, or exported to userspace via sysfs. To make
them easier to interpret independently on kernel version and config, we
want to dump also the symbolic flag names. So far this has been done
with repeated calls to pr_cont(), which is unreliable on SMP, and not
usable for e.g. sysfs export.
To get a more reliable and universal solution, this patch extends
printk() format string for pointers to handle the page flags (%pGp),
gfp_flags (%pGg) and vma flags (%pGv). Existing users of
dump_flag_names() are converted and simplified.
It would be possible to pass flags by value instead of pointer, but the
%p format string for pointers already has extensions for various kernel
structures, so it's a good fit, and the extra indirection in a
non-critical path is negligible.
[linux@rasmusvillemoes.dk: lots of good implementation suggestions]
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The kptr_restrict flag, when set to 1, only prints the kernel address
when the user has CAP_SYSLOG. When it is set to 2, the kernel address
is always printed as zero. When set to 1, this needs to check whether
or not we're in IRQ.
However, when set to 2, this check is unneccessary, and produces
confusing results in dmesg. Thus, only make sure we're not in IRQ when
mode 1 is used, but not mode 2.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move switch case to the netdev_features_string() and rename it to
netdev_bits(). In the future we can extend it as needed.
Here we replace the fallback of %pN from '%p' with possible flags to
sticter '0x%p' without any flags variation.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
special_hex_number() is a helper to print a fixed size type in a hex
format with '0x' prefix, zero padding, and small letters. In the module
we have already several copies of such code. Consolidate them under
special_hex_number() helper.
There are couple of differences though.
It seems nobody cared about the output in case of CONFIG_KALLSYMS=n,
when printing symbol address, because the asked field width is not
enough to care last 2 characters in the string represantation of the
pointer. Fixed here.
The %pNF specifier used to be allowed with a specific field width,
though there is neither any user of it nor mention the possibility in
the documentation.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The field width is overloaded to pass some extra information for some %p
extensions (e.g. #bits for %pb). But we might silently truncate the
passed value when we stash it in struct printf_spec (see e.g.
"lib/vsprintf.c: expand field_width to 24 bits"). Hopefully 23 value
bits should now be enough for everybody, but if not, let's make some
noise.
Do the same for the precision. In both cases, clamping seems more
sensible than truncating. While, according to POSIX, "A negative
precision is taken as if the precision were omitted.", the kernel's
printf has always treated that case as if the precision was 0, so we use
that as lower bound. For the field width, the smallest representable
value is actually -(1<<23), but a negative field width means 'set the
LEFT flag and use the absolute value', so we want the absolute value to
fit.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Joe Perches <joe@perches.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Maurizio Lombardi <mlombard@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
One consequence of the reorganization of struct printf_spec to make
field_width 24 bits was that number() gained about 180 bytes. Since
spec is never passed to other functions, we can help gcc make number()
lose most of that extra weight by using local variables for the field
width and precision.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Joe Perches <joe@perches.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Maurizio Lombardi <mlombard@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Maurizio Lombardi reported a problem [1] with the %pb extension: It
doesn't work for sufficiently large bitmaps, since the size is stashed
in the field_width field of the struct printf_spec, which is currently
an s16. Concretely, this manifested itself in
/sys/bus/pseudo/drivers/scsi_debug/map being empty, since the bitmap
printer got a size of 0, which is the 16 bit truncation of the actual
bitmap size.
We do want to keep struct printf_spec at 8 bytes so that it can cheaply
be passed by value. The qualifier field is only used for internal
bookkeeping in format_decode, so we might as well use a local variable
for that. This gives us an additional 8 bits, which we can then use for
the field width.
To stay in 8 bytes, we need to do a little rearranging and make the type
member a bitfield as well. For consistency, change all the members to
bit fields. gcc doesn't generate much worse code with these changes (in
fact, bloat-o-meter says we save 300 bytes - which I think is a little
surprising).
I didn't find a BUILD_BUG/compiletime_assertion/... which would work
outside function context, so for now I just open-coded it.
[1] http://thread.gmane.org/gmane.linux.kernel/2034835
[akpm@linux-foundation.org: avoid open-coded BUILD_BUG_ON]
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reported-by: Maurizio Lombardi <mlombard@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Joe Perches <joe@perches.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If the string corresponding to a %s specifier can change under us, we
might end up copying a \0 byte to the output buffer. There might be
callers who expect the output buffer to contain a genuine C string whose
length is exactly the snprintf return value (assuming truncation hasn't
happened or has been checked for).
We can avoid this by only passing over the source string once, stopping
the first time we meet a nul byte (or when we reach the given
precision), and then letting widen_string() handle left/right space
padding. As a small bonus, this code reuse also makes the generated
code slightly smaller.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Joe Perches <joe@perches.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Maurizio Lombardi <mlombard@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is pure code movement, making sure the widen_string() helper is
defined before the string() function.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Joe Perches <joe@perches.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Maurizio Lombardi <mlombard@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull out the logic in dentry_name() which handles field width space
padding, in preparation for reusing it from string(). Rename the
widen() helper to move_right(), since it is used for handling the
!(flags & LEFT) case.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Joe Perches <joe@perches.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Maurizio Lombardi <mlombard@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This allow to directly print block_device name.
Currently one should use bdevname() with temporal char buffer.
This is very ineffective because bloat stack usage for deep IO call-traces
Example:
%pg -> sda, sda1 or loop0p1
[AV: fixed a minor braino - position updates should not be dependent
upon having reached the of buffer]
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
%n is no longer just ignored; it results in early return from vsnprintf.
Also add a request to add test cases for future %p extensions.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As a quick
git grep -E '%[ +0#-]*#[ +0#-]*(\*|[0-9]+)?(\.(\*|[0-9]+)?)?p'
shows, nobody uses the # flag with %p. Should one try to do so, one
will be met with
warning: `#' flag used with `%p' gnu_printf format [-Wformat]
(POSIX and C99 both say "... For other conversion specifiers, the
behavior is undefined.". Obviously, the kernel can choose to define
the behaviour however it wants, but as long as gcc issues that
warning, users are unlikely to show up.)
Since default_width is effectively always 2*sizeof(void*), we can
simplify the prologue of pointer() and save a few instructions.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Martin Kletzander <mkletzan@redhat.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Quoting from 2aa2f9e21e ("lib/vsprintf.c: improve sanity check in
vsnprintf()"):
On 64 bit, size may very well be huge even if bit 31 happens to be 0.
Somehow it doesn't feel right that one can pass a 5 GiB buffer but not a
3 GiB one. So cap at INT_MAX as was probably the intention all along.
This is also the made-up value passed by sprintf and vsprintf.
I should have seen this copy-pasted instance back then, but let's just
do it now.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Martin Kletzander <mkletzan@redhat.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If we meet any invalid or unsupported format specifier, 'handling' it by
just printing it as a literal string is not safe: Presumably the format
string and the arguments passed gcc's type checking, but that means
something like sprintf(buf, "%n %pd", &intvar, dentry) would end up
interpreting &intvar as a struct dentry*.
When the offending specifier was %n it used to be at the end of the format
string, but we can't rely on that always being the case. Also, gcc
doesn't complain about some more or less exotic qualifiers (or 'length
modifiers' in posix-speak) such as 'j' or 'q', but being unrecognized by
the kernel's printf implementation, they'd be interpreted as unknown
specifiers, and the rest of arguments would be interpreted wrongly.
So let's complain about anything we don't understand, not just %n, and
stop pretending that we'd be able to make sense of the rest of the
format/arguments. If the offending specifier is in a printk() call we
unfortunately only get a "BUG: recent printk recursion!", but at least
direct users of the sprintf family will be caught.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Martin Kletzander <mkletzan@redhat.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move all pointer-formatting documentation to one place in the code and one
place in the documentation instead of keeping it in three places with
different level of completeness. Documentation/printk-formats.txt has
detailed information about each modifier, docstring above pointer() has
short descriptions of them (as that is the function dealing with %p) and
docstring above vsprintf() is removed as redundant. Both docstrings in
the code that were modified are updated with a reminder of updating the
documentation upon any further change.
[akpm@linux-foundation.org: fix comment]
Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This file uses the clk API so it should include clk.h directly
instead of indirectly including it through clk-provider.h.
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
I hadn't had enough coffee when I wrote this. Currently, the final
increment of buf depends on the value loaded from the table, and
causes gcc to emit a cmov immediately before the return. It is smarter
to let it depend on r, since the increment can then be computed in
parallel with the final load/store pair. It also shaves 16 bytes of
.text.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Tejun Heo <tj@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The most expensive part of decimal conversion is the divisions by 10
(albeit done using reciprocal multiplication with appropriately chosen
constants). I decided to see if one could eliminate around half of
these multiplications by emitting two digits at a time, at the cost of a
200 byte lookup table, and it does indeed seem like there is something
to be gained, especially on 64 bits. Microbenchmarking shows
improvements ranging from -50% (for numbers uniformly distributed in [0,
2^64-1]) to -25% (for numbers heavily biased toward the smaller end, a
more realistic distribution).
On a larger scale, perf shows that top, one of the big consumers of /proc
data, uses 0.5-1.0% fewer cpu cycles.
I had to jump through some hoops to get the 32 bit code to compile and run
on my 64 bit machine, so I'm not sure how relevant these numbers are, but
just for comparison the microbenchmark showed improvements between -30%
and -10%.
The bloat-o-meter costs are around 150 bytes (the generated code is a
little smaller, so it's not the full 200 bytes) on both 32 and 64 bit.
I'm aware that extra cache misses won't show up in a microbenchmark as
used above, but on the other hand decimal conversions often happen in bulk
(for example in the case of top).
I have of course tested that the new code generates the same output as the
old, for both the first and last 1e10 numbers in [0,2^64-1] and 4e9
'random' numbers in-between.
Test and verification code on github: https://github.com/Villemoes/dec.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Tested-by: Jeff Epler <jepler@unpythonic.net>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The current semantics of string_escape_mem are inadequate for one of its
current users, vsnprintf(). If that is to honour its contract, it must
know how much space would be needed for the entire escaped buffer, and
string_escape_mem provides no way of obtaining that (short of allocating a
large enough buffer (~4 times input string) to let it play with, and
that's definitely a big no-no inside vsnprintf).
So change the semantics for string_escape_mem to be more snprintf-like:
Return the size of the output that would be generated if the destination
buffer was big enough, but of course still only write to the part of dst
it is allowed to, and (contrary to snprintf) don't do '\0'-termination.
It is then up to the caller to detect whether output was truncated and to
append a '\0' if desired. Also, we must output partial escape sequences,
otherwise a call such as snprintf(buf, 3, "%1pE", "\123") would cause
printf to write a \0 to buf[2] but leaving buf[0] and buf[1] with whatever
they previously contained.
This also fixes a bug in the escaped_string() helper function, which used
to unconditionally pass a length of "end-buf" to string_escape_mem();
since the latter doesn't check osz for being insanely large, it would
happily write to dst. For example, kasprintf(GFP_KERNEL, "something and
then %pE", ...); is an easy way to trigger an oops.
In test-string_helpers.c, the -ENOMEM test is replaced with testing for
getting the expected return value even if the buffer is too small. We
also ensure that nothing is written (by relying on a NULL pointer deref)
if the output size is 0 by passing NULL - this has to work for
kasprintf("%pE") to work.
In net/sunrpc/cache.c, I think qword_add still has the same semantics.
Someone should definitely double-check this.
In fs/proc/array.c, I made the minimum possible change, but longer-term it
should stop poking around in seq_file internals.
[andriy.shevchenko@linux.intel.com: simplify qword_add]
[andriy.shevchenko@linux.intel.com: add missed curly braces]
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The helper hex_string() is broken in two ways. First, it doesn't
increment buf regardless of whether there is room to print, so callers
such as kasprintf() that try to probe the correct storage to allocate will
get a too small return value. But even worse, kasprintf() (and likely
anyone else trying to find the size of the result) pass NULL for buf and 0
for size, so we also have end == NULL. But this means that the end-1 in
hex_string() is (char*)-1, so buf < end-1 is true and we get a NULL
pointer deref. I double-checked this with a trivial kernel module that
just did a kasprintf(GFP_KERNEL, "%14ph", "CrashBoomBang").
Nobody seems to be using %ph with kasprintf, but we might as well fix it
before it hits someone.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add format specifiers for printing struct clk:
- '%pC' or '%pCn': name (Common Clock Framework) or address (legacy
clock framework) of the clock,
- '%pCr': rate of the clock.
[akpm@linux-foundation.org: omit code if !CONFIG_HAVE_CLK]
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mike Turquette <mturquette@linaro.org>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Making ZEROPAD == '0'-' ', we can eliminate a few more instructions.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
gcc doesn't merge or overlap const char[] objects with identical contents
(probably language lawyers would also insist that these things have
different addresses), but there's no reason to have the string
"0123456789ABCDEF" occur in multiple places. hex_asc_upper is declared in
kernel.h and defined in lib/hexdump.c, which is unconditionally compiled
in.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
At least since the initial git commit, when base was passed as a separate
parameter, number() has only been called with bases 8, 10 and 16. I'm
guessing that 66 was to accommodate 64 0/1, a sign and a '\0', but the
buffer is only used for the actual digits. Octal digits carry 3 bits of
information, so 24 is enough. Spell that 3*sizeof(num) so one less place
needs to be changed should long long ever be 128 bits. Also remove the
commented-out code that would handle an arbitrary base.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since FORMAT_TYPE_INT is simply 1 more than FORMAT_TYPE_UINT, and
similarly for BYTE/UBYTE, SHORT/USHORT, LONG/ULONG, we can eliminate a few
instructions by making SIGN have the value 1 instead of 2, and then use
arithmetic instead of branches for computing the right spec->type. It's a
little hacky, but certainly in the same spirit as SMALL needing to have
the value 0x20. For example for the spec->qualifier == 'l' case, gcc now
generates
75e: 0f b6 53 01 movzbl 0x1(%rbx),%edx
762: 83 e2 01 and $0x1,%edx
765: 83 c2 09 add $0x9,%edx
768: 88 13 mov %dl,(%rbx)
instead of
763: 0f b6 53 01 movzbl 0x1(%rbx),%edx
767: 83 e2 02 and $0x2,%edx
76a: 80 fa 01 cmp $0x1,%dl
76d: 19 d2 sbb %edx,%edx
76f: 83 c2 0a add $0xa,%edx
772: 88 13 mov %dl,(%rbx)
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Steven Rostedt (VMware)
Andrei Vagin
Adam Borowski
Linus Torvalds
Sergey Senozhatsky
Jonathan Corbet
Tobin C. Harding
Mark Rutland
Pantelis Antoniou
Christoph Hellwig
Joe Perches
mchehab@s-opensource.com
Alexey Dobriyan
Andy Shevchenko
Jessica Yu
Vlastimil Babka
Jason A. Donenfeld
Rasmus Villemoes
Dmitry Monakhov
Martin Kletzander
Stephen Boyd
Geert Uytterhoeven