* 'i2c-for-linus' of git://jdelvare.pck.nerim.net/jdelvare-2.6:
i2c: Warn on deprecated binding model use
eeprom: More consistent symbol names
eeprom: Move 93cx6 eeprom driver to /drivers/misc/eeprom
spi: Move at25 (for SPI eeproms) to /drivers/misc/eeprom
i2c: Move old eeprom driver to /drivers/misc/eeprom
i2c: Move at24 to drivers/misc/eeprom
i2c: Quilt tree has moved
i2c: Delete many unused adapter IDs
i2c: Delete 10 unused driver IDs
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6:
sparc64: Fix DAX handling via userspace access from kernel.
sparc64: Annotate sparc64 specific syscalls with SYSCALL_DEFINEx()
[CVE-2009-0029] sparc: Enable syscall wrappers for 64-bit
sparc64: Initialize FHC/CLOCK LED platform_device 'id' field correctly.
sparc64: fix modpost failure
sparc64: fix readout of cpu/fpu type
Probe the new mdio node added by b31a1d8b. Fix kernel panic problem when
gianfar driver wants to get the of_platform_device of that mdio.
Signed-off-by: Li Yang <leoli@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Now that all EEPROM drivers live in the same place, let's harmonize
their symbol names.
Also fix eeprom's dependencies, it definitely needs sysfs, and is no
longer experimental after many years in the kernel tree.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
Cc: David Brownell <dbrownell@users.sourceforge.net>
swab.h seems to have been missed during the header merge.
Add conditionals similar to byteorder.h and remove the
now unnecessary byteorder_no/mm.h
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/djbw/async_tx:
i.MX31: framebuffer driver
i.MX31: Image Processing Unit DMA and IRQ drivers
dmaengine: add async_tx_clear_ack() macro
dmaengine: dma_issue_pending_all == nop when CONFIG_DMA_ENGINE=n
dmaengine: kill some dubious WARN_ONCEs
fsldma: print correct IRQ on mpc83xx
fsldma: check for NO_IRQ in fsl_dma_chan_remove()
dmatest: Use custom map/unmap for destination buffer
fsldma: use a valid 'device' for dma_pool_create
dmaengine: fix dependency chaining
* 'sh/for-2.6.29' of git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6: (22 commits)
dma-coherent: Restore dma_alloc_from_coherent() large alloc fall back policy.
dma-coherent: per-device coherent area is in pages, not bytes.
sh: fix unaligned and nonexistent address handling
nommu: Stub in vm_map_ram()/vm_unmap_ram()/vm_unmap_aliases().
sh: fix sh-sci / early printk build on sh7723
sh: export the sh7343 JPU to user space
sh: update defconfigs.
serial: sh-sci: Fix up SH7720/SH7721 SCI build.
sh: Kill off obsolete busses from arch/sh/Kconfig.
sh: sh7785lcr/highlander/hp6xx need linux/irq.h.
sh: Migo-R MMC support using spi_gpio and mmc_spi.
sh: ap325rxa MMC support using spi_gpio and mmc_spi
sh: mach-x3proto: needs linux/irq.h.
sh: Drop the BKL from sys_execve() on SH-5.
sh: convert rsk7203 to use smsc911x.
sh: convert magicpanelr2 platform to use smsc911x.
sh: convert ap325rxa platform to use smsc911x.
sh: mach-migor: Add tw9910 support.
sh: mach-migor: Delete soc_camera_platform setup.
sh: mach-migor: Add ov772x support.
...
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
debugobjects: add and use INIT_WORK_ON_STACK
rcu: remove duplicate CONFIG_RCU_CPU_STALL_DETECTOR
relay: fix lock imbalance in relay_late_setup_files
oprofile: fix uninitialized use of struct op_entry
rcu: move Kconfig menu
softlock: fix false panic which can occur if softlockup_thresh is reduced
rcu: add __cpuinit to rcu_init_percpu_data()
* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
hrtimers: fix inconsistent lock state on resume in hres_timers_resume
time-sched.c: tick_nohz_update_jiffies should be static
locking, hpet: annotate false positive warning
kernel/fork.c: unused variable 'ret'
itimers: remove the per-cpu-ish-ness
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (29 commits)
xen: unitialised return value in xenbus_write_transaction
x86: fix section mismatch warning
x86: unmask CPUID levels on Intel CPUs, fix
x86: work around PAGE_KERNEL_WC not getting WC in iomap_atomic_prot_pfn.
x86: use standard PIT frequency
xen: handle highmem pages correctly when shrinking a domain
x86, mm: fix pte_free()
xen: actually release memory when shrinking domain
x86: unmask CPUID levels on Intel CPUs
x86: add MSR_IA32_MISC_ENABLE bits to <asm/msr-index.h>
x86: fix PTE corruption issue while mapping RAM using /dev/mem
x86: mtrr fix debug boot parameter
x86: fix page attribute corruption with cpa()
Revert "x86: signal: change type of paramter for sys_rt_sigreturn()"
x86: use early clobbers in usercopy*.c
x86: remove kernel_physical_mapping_init() from init section
fix: crash: IP: __bitmap_intersects+0x48/0x73
cpufreq: use work_on_cpu in acpi-cpufreq.c for drv_read and drv_write
work_on_cpu: Use our own workqueue.
work_on_cpu: don't try to get_online_cpus() in work_on_cpu.
...
Impact: re-enable CPUID unmasking on affected processors
As far as I am capable of discerning from the documentation,
MSR_IA32_MISC_ENABLE should be available for all family 0xf CPUs, as
well as family 6 for model >= 0xd (newer Pentium M).
The documentation on this isn't ideal, so we need to be on the lookout
for errors, still.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Here function vmi_activate calls a init function activate_vmi , which
causes the following section mismatch warnings:
LD arch/x86/kernel/built-in.o
WARNING: arch/x86/kernel/built-in.o(.text+0x13ba9): Section mismatch
in reference from the function vmi_activate() to the function
.init.text:vmi_time_init()
The function vmi_activate() references
the function __init vmi_time_init().
This is often because vmi_activate lacks a __init
annotation or the annotation of vmi_time_init is wrong.
WARNING: arch/x86/kernel/built-in.o(.text+0x13bd1): Section mismatch
in reference from the function vmi_activate() to the function
.devinit.text:vmi_time_bsp_init()
The function vmi_activate() references
the function __devinit vmi_time_bsp_init().
This is often because vmi_activate lacks a __devinit
annotation or the annotation of vmi_time_bsp_init is wrong.
WARNING: arch/x86/kernel/built-in.o(.text+0x13bdb): Section mismatch
in reference from the function vmi_activate() to the function
.devinit.text:vmi_time_ap_init()
The function vmi_activate() references
the function __devinit vmi_time_ap_init().
This is often because vmi_activate lacks a __devinit
annotation or the annotation of vmi_time_ap_init is wrong.
Fix it by marking vmi_activate() as __init too.
Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix boot hang on pre-model-15 Intel CPUs
rdmsrl_safe() does not work in very early bootup code yet, because we
dont have the pagefault handler installed yet so exception section
does not get parsed. rdmsr_safe() will just crash and hang the bootup.
So limit the MSR_IA32_MISC_ENABLE MSR read to those CPU types that
support it.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The EH message for NODEV_HINT path was describing the opposite
condition. Fix it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
In the absence of PAT, PAGE_KERNEL_WC ends up mapping to a memory type that
gets UC behavior even in the presence of a WC MTRR covering the area in
question. By swapping to PAGE_KERNEL_UC_MINUS, we can get the actual
behavior the caller wanted (WC if you can manage it, UC otherwise).
This recovers the 40% performance improvement of using WC in the DRM
to upload vertex data.
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Tomi Valkeinen reports:
Running with latest linux-omap kernel on OMAP3 SDP board, I have
problem with iounmap(). It looks like iounmap() does not properly
free large areas. Below is a test which fails for me in 6-7 loops.
for (i = 0; i < 200; ++i) {
vaddr = ioremap(paddr, size);
if (!vaddr) {
printk("couldn't ioremap\n");
break;
}
iounmap(vaddr);
}
The changes to vmalloc.c weren't reflected in the ARM ioremap
implementation. Turns out the fix is rather simple.
Tested-by: Tomi Valkeinen <tomi.valkeinen@nokia.com>
Tested-by: Matt Gerassimoff <mgeras@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
the RDC and ELAN platforms use slighly different PIT clocks, resulting in
a timex.h hack that changes PIT_TICK_RATE during build time. But if a
tester enables any of these platform support .config options, the PIT
will be miscalibrated on standard PC platforms.
So use one frequency - in a subsequent patch we'll add a quirk to allow
x86 platforms to define different PIT frequencies.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The old matching algorithm was too fuzzy, causing false positives.
For example, when asked for device D connection C1 and we only find
device D connection C2, we return that as a valid match despite the
connection names being different.
Change the algorithm such that:
An entry with a NULL ID is assumed to be a wildcard.
If an entry has a device ID, it must match
If an entry has a connection ID, it must match
However, we maintain the order of precidence while still only doing
a single pass over all entries: dev+con > dev only > con only.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
From: David Brownell <dbrownell@users.sourceforge.net>
Subject: ARM/mach-davinci/usb.c buildfix
CC arch/arm/mach-davinci/usb.o
arch/arm/mach-davinci/usb.c:60: error: 'IRQ_USBINT' undeclared here (not in a function)
make[1]: *** [arch/arm/mach-davinci/usb.o] Error 1
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
On -rt we were seeing spurious bad page states like:
Bad page state in process 'firefox'
page:c1bc2380 flags:0x40000000 mapping:c1bc2390 mapcount:0 count:0
Trying to fix it up, but a reboot is needed
Backtrace:
Pid: 503, comm: firefox Not tainted 2.6.26.8-rt13 #3
[<c043d0f3>] ? printk+0x14/0x19
[<c0272d4e>] bad_page+0x4e/0x79
[<c0273831>] free_hot_cold_page+0x5b/0x1d3
[<c02739f6>] free_hot_page+0xf/0x11
[<c0273a18>] __free_pages+0x20/0x2b
[<c027d170>] __pte_alloc+0x87/0x91
[<c027d25e>] handle_mm_fault+0xe4/0x733
[<c043f680>] ? rt_mutex_down_read_trylock+0x57/0x63
[<c043f680>] ? rt_mutex_down_read_trylock+0x57/0x63
[<c0218875>] do_page_fault+0x36f/0x88a
This is the case where a concurrent fault already installed the PTE and
we get to free the newly allocated one.
This is due to pgtable_page_ctor() doing the spin_lock_init(&page->ptl)
which is overlaid with the {private, mapping} struct.
union {
struct {
unsigned long private;
struct address_space *mapping;
};
spinlock_t ptl;
struct kmem_cache *slab;
struct page *first_page;
};
Normally the spinlock is small enough to not stomp on page->mapping, but
PREEMPT_RT=y has huge 'spin'locks.
But lockdep kernels should also be able to trigger this splat, as the
lock tracking code grows the spinlock to cover page->mapping.
The obvious fix is calling pgtable_page_dtor() like the regular pte free
path __pte_free_tlb() does.
It seems all architectures except x86 and nm10300 already do this, and
nm10300 doesn't seem to use pgtable_page_ctor(), which suggests it
doesn't do SMP or simply doesnt do MMU at all or something.
Signed-off-by: Peter Zijlstra <a.p.zijlsta@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
Add wrapper functions for the following compat system calls:
* readahead
* sendfile64
* tkill
* tgkill
* keyctl
This ensures that the high order bits of the parameter registers are correctly
sign extended.
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Precreate stop_machine threads in case the machine supports ETR/STP.
Otherwise we might deadlock if a time sync operation gets scheduled
and the creation of stop_machine threads would cause disk I/O.
This is just the minimal fix.
The real fix would be to only precreate stop_machine threads if
ETR/STP is actually used. But that would be a rather large and
complicated patch.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
On (initial) cpu hotplug the lowcore values for user_timer and
system_timer don't get initialized like they would get on each
process schedule.
On initial start of secondary cpus this leads to the situation
where per thread user/system_timer values are larger than the
corresponding contents of the lowcore. When later calculating
time spent in user/system context the result can be negative.
So for cpu hotplug we should manually initialize lowcore values.
Fixes this bug:
Kernel BUG at 000ec080 [verbose debug info unavailable]
fixpoint divide exception: 0009 [#1] PREEMPT SMP
Modules linked in:
CPU: 10 Not tainted 2.6.28 #4
Process sysctl (pid: 975, task: 3fa752e0, ksp: 3fbebca0)
Krnl PSW : 070c1000 800ec080 (show_stat+0x390/0x5fc)
R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:0 CC:1 PM:0
Krnl GPRS: 7fffffff fefc7ce5 3faec080 003879ae
00000001 01388000 7fffffff 01388000
00000000 00000000 0049ad50 3fbebcf8
01388000 002f51a8 800ec1fe 3fbebcf8
Krnl Code: 800ec076: 9001b188 stm %r0,%r1,392(%r11)
800ec07a: 9801b0c0 lm %r0,%r1,192(%r11)
800ec07e: 1d05 dr %r0,%r5
>800ec080: 9001b0c0 stm %r0,%r1,192(%r11)
800ec084: 5860b0c4 l %r6,196(%r11)
800ec088: 1806 lr %r0,%r6
800ec08a: 8c800001 srdl %r8,1
800ec08e: 1d87 dr %r8,%r7
Call Trace:
([<00000000000ec1ee>] show_stat+0x4fe/0x5fc)
[<00000000000c13e8>] seq_read+0xc4/0x3ac
[<00000000000e4796>] proc_reg_read+0x6e/0x9c
[<00000000000a6a44>] vfs_read+0x78/0x100
[<00000000000a6ba8>] sys_read+0x40/0x80
[<00000000000234a8>] sysc_do_restart+0x1a/0x1e
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
When 31 bit user space programs call sigaltstack on a 64 bit Linux
OS, the system call returns -1 with errno=EFAULT. The 31 bit pointer passed
to the system call is extended to 64 bit, but the high order bits are not
set to zero. The kernel detects the invalid user space pointer and
returns -EFAULT. To solve the problem, sys32_sigaltstack_wrapper()
instead of sys32_sigaltstack() has to be called. The wrapper function sets
the high order bits to zero.
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Use the personality() macro to mask out all bits that are not
relevant for the personality type.
The personality field contains bits for other things as well,
so without masking out the not relevalent bits the comparison
won't do what is expected.
Reported-by: Andreas Krebbel <krebbel@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cleanup the cpuid check for DS configuration.
This also fixes a Corei7 CPUID enumeration bug.
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: Fix debugobjects warning
debugobject enabled kernels spit out a warning in hpet code due to a
workqueue which is initialized on stack.
Add INIT_WORK_ON_STACK() which calls init_timer_on_stack() and use it
in hpet.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Impact: Fixes crashes with misconfigured BIOSes on XSAVE hardware
Avuton Olrich reported early boot crashes with v2.6.28 and
bisected it down to dc1e35c6e95e8923cf1d3510438b63c600fee1e2
("x86, xsave: enable xsave/xrstor on cpus with xsave support").
If the CPUID limit bit in MSR_IA32_MISC_ENABLE is set, clear it to
make all CPUID information available. This is required for some
features to work, in particular XSAVE.
Reported-and-bisected-by: Avuton Olrich <avuton@gmail.com>
Tested-by: Avuton Olrich <avuton@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Impact: None (new bit definitions currently unused)
Add bit definitions for the MSR_IA32_MISC_ENABLE MSRs to
<asm/msr-index.h>.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Beschorner Daniel reported:
> hwinfo problem since 2.6.28, showing this in the oops:
> Corrupted page table at address 7fd04de3ec00
Also, PaX Team reported a regression with this commit:
> commit 9542ada803198e6eba29d3289abb39ea82047b92
> Author: Suresh Siddha <suresh.b.siddha@intel.com>
> Date: Wed Sep 24 08:53:33 2008 -0700
>
> x86: track memtype for RAM in page struct
This commit breaks mapping any RAM page through /dev/mem, as the
reserve_memtype() was not initializing the return attribute type and as such
corrupting the PTE entry that was setup with the return attribute type.
Because of this bug, application mapping this RAM page through /dev/mem
will die with "Corrupted page table at address xxxx" message in the kernel
log and also the kernel identity mapping which maps the underlying RAM
page gets converted to UC.
Fix this by initializing the return attribute type before calling
reserve_ram_pages_type()
Reported-by: PaX Team <pageexec@freemail.hu>
Reported-and-tested-by: Beschorner Daniel <Daniel.Beschorner@facton.com>
Tested-and-Acked-by: PaX Team <pageexec@freemail.hu>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This is a framebuffer driver for i.MX31 SoCs. It only supports synchronous
displays, vertical panning supported, no overlay support.
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Guennadi Liakhovetski <lg@denx.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
while looking at:
http://bugzilla.kernel.org/show_bug.cgi?id=11541
I realized that the mtrr.show param cannot work, because
the code is processed much too early.
This patch:
- Declares mtrr.show as early_param
- Stays consistent with the previous param (which I doubt
that it ever worked), so mtrr.show=1 would still work
- Declares mtrr_show as initdata
Signed-off-by: Thomas Renninger <trenn@suse.de>
Acked-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix sporadic slowdowns and warning messages
This patch fixes a performance issue reported by Linus on his
Nehalem system. While Linus reverted the PAT patch (commit
58dab916dfb57328d50deb0aa9b3fc92efa248ff) which exposed the issue,
existing cpa() code can potentially still cause wrong(page attribute
corruption) behavior.
This patch also fixes the "WARNING: at arch/x86/mm/pageattr.c:560" that
various people reported.
In 64bit kernel, kernel identity mapping might have holes depending
on the available memory and how e820 reports the address range
covering the RAM, ACPI, PCI reserved regions. If there is a 2MB/1GB hole
in the address range that is not listed by e820 entries, kernel identity
mapping will have a corresponding hole in its 1-1 identity mapping.
If cpa() happens on the kernel identity mapping which falls into these holes,
existing code fails like this:
__change_page_attr_set_clr()
__change_page_attr()
returns 0 because of if (!kpte). But doesn't
set cpa->numpages and cpa->pfn.
cpa_process_alias()
uses uninitialized cpa->pfn (random value)
which can potentially lead to changing the page
attribute of kernel text/data, kernel identity
mapping of RAM pages etc. oops!
This bug was easily exposed by another PAT patch which was doing
cpa() more often on kernel identity mapping holes (physical range between
max_low_pfn_mapped and 4GB), where in here it was setting the
cache disable attribute(PCD) for kernel identity mappings aswell.
Fix cpa() to handle the kernel identity mapping holes. Retain
the WARN() for cpa() calls to other not present address ranges
(kernel-text/data, ioremap() addresses)
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
unaligned and nonexistent address causes wrong exception
handling in traps_32.c(handle_unaligned_access).
'handle_unalinged_ins' should return -EFAULT if address error
is fixed up with kernel exception table, otherwise
'handle_unaligned_access' increases already fixed program counter
and then crash.
for example
ioctl(fd, TCGETA, (struct termio *)-1)
never return and stay in TASK_UNINTERRUPTIBLE state forever
in my kernel.
Signed-off-by: SUGIOKA Toshinobu <sugioka@itonet.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This patch exports the sh7343 JPU to user space using uio_pdrv_genirq,
very similar to the sh7722 JPU patch by Hayama-san.
While at it fix up the end of the sh7722 JPU iomem resource.
Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
ISA can go away now that the hd6446x PCMCIA drivers no longer exist
in-tree. The rationale for enabling CONFIG_ISA in the first place is
likewise no longer valid given that the subsystem has changed since
the time that assertion was valid.
While we are at it, kill off SBUS, MCA, EISA, and so on. These are
not supported and never will be.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This patch adds CN9 MMC support for MigoR using the mmc_spi
driver on top of the bitbanging spi_gpio driver.
Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This reverts commit 4217458dafaa57d8e26a46f5d05ab8c53cf64191.
Justin Madru bisected this commit, it was causing weird Firefox
crashes.
The reason is that GCC mis-optimizes (re-uses) the on-stack parameters of
the calling frame, which corrupts the syscall return pt_regs state and
thus corrupts user-space register state.
So we go back to the slightly less clean but more optimization-safe
method of getting to pt_regs. Also add a comment to explain this.
Resolves: http://bugzilla.kernel.org/show_bug.cgi?id=12505
Reported-and-bisected-by: Justin Madru <jdm64@gawab.com>
Tested-by: Justin Madru <jdm64@gawab.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix rare (but currently harmless) miscompile with certain configs and gcc versions
Hugh Dickins noticed that strncpy_from_user() was miscompiled
in some circumstances with gcc 4.3.
Thanks to Hugh's excellent analysis it was easy to track down.
Hugh writes:
> Try building an x86_64 defconfig 2.6.29-rc1 kernel tree,
> except not quite defconfig, switch CONFIG_PREEMPT_NONE=y
> and CONFIG_PREEMPT_VOLUNTARY off (because it expands a
> might_fault() there, which hides the issue): using a
> gcc 4.3.2 (I've checked both openSUSE 11.1 and Fedora 10).
>
> It generates the following:
>
> 0000000000000000 <__strncpy_from_user>:
> 0: 48 89 d1 mov %rdx,%rcx
> 3: 48 85 c9 test %rcx,%rcx
> 6: 74 0e je 16 <__strncpy_from_user+0x16>
> 8: ac lods %ds:(%rsi),%al
> 9: aa stos %al,%es:(%rdi)
> a: 84 c0 test %al,%al
> c: 74 05 je 13 <__strncpy_from_user+0x13>
> e: 48 ff c9 dec %rcx
> 11: 75 f5 jne 8 <__strncpy_from_user+0x8>
> 13: 48 29 c9 sub %rcx,%rcx
> 16: 48 89 c8 mov %rcx,%rax
> 19: c3 retq
>
> Observe that "sub %rcx,%rcx; mov %rcx,%rax", whereas gcc 4.2.1
> (and many other configs) say "sub %rcx,%rdx; mov %rdx,%rax".
> Isn't it returning 0 when it ought to be returning strlen?
The asm constraints for the strncpy_from_user() result were missing an
early clobber, which tells gcc that the last output arguments
are written before all input arguments are read.
Also add more early clobbers in the rest of the file and fix 32-bit
usercopy.c in the same way.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
[ since this API is rarely used and no in-kernel user relies on a 'len'
return value (they only rely on negative return values) this miscompile
was never noticed in the field. But it's worth fixing it nevertheless. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
