commit 136f39ddc53db3bcee2befbe323a56d4fbf06da8 upstream.
The Linux Kernel contains some inline assembly source code which has
wrong asm register constraints in arch/ia64/include/asm/futex.h.
I observed this on Kernel 3.2.23 but it is also true on the most
recent Kernel 3.9-rc1.
File arch/ia64/include/asm/futex.h:
static inline int
futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
u32 oldval, u32 newval)
{
if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
return -EFAULT;
{
register unsigned long r8 __asm ("r8");
unsigned long prev;
__asm__ __volatile__(
" mf;; \n"
" mov %0=r0 \n"
" mov ar.ccv=%4;; \n"
"[1:] cmpxchg4.acq %1=[%2],%3,ar.ccv \n"
" .xdata4 \"__ex_table\", 1b-., 2f-. \n"
"[2:]"
: "=r" (r8), "=r" (prev)
: "r" (uaddr), "r" (newval),
"rO" ((long) (unsigned) oldval)
: "memory");
*uval = prev;
return r8;
}
}
The list of output registers is
: "=r" (r8), "=r" (prev)
The constraint "=r" means that the GCC has to maintain that these vars
are in registers and contain valid info when the program flow leaves
the assembly block (output registers).
But "=r" also means that GCC can put them in registers that are used
as input registers. Input registers are uaddr, newval, oldval on the
example.
The second assembly instruction
" mov %0=r0 \n"
is the first one which writes to a register; it sets %0 to 0. %0 means
the first register operand; it is r8 here. (The r0 is read-only and
always 0 on the Itanium; it can be used if an immediate zero value is
needed.)
This instruction might overwrite one of the other registers which are
still needed.
Whether it really happens depends on how GCC decides what registers it
uses and how it optimizes the code.
The objdump utility can give us disassembly.
The futex_atomic_cmpxchg_inatomic() function is inline, so we have to
look for a module that uses the funtion. This is the
cmpxchg_futex_value_locked() function in
kernel/futex.c:
static int cmpxchg_futex_value_locked(u32 *curval, u32 __user *uaddr,
u32 uval, u32 newval)
{
int ret;
pagefault_disable();
ret = futex_atomic_cmpxchg_inatomic(curval, uaddr, uval, newval);
pagefault_enable();
return ret;
}
Now the disassembly. At first from the Kernel package 3.2.23 which has
been compiled with GCC 4.4, remeber this Kernel seemed to work:
objdump -d linux-3.2.23/debian/build/build_ia64_none_mckinley/kernel/futex.o
0000000000000230 <cmpxchg_futex_value_locked>:
230: 0b 18 80 1b 18 21 [MMI] adds r3=3168,r13;;
236: 80 40 0d 00 42 00 adds r8=40,r3
23c: 00 00 04 00 nop.i 0x0;;
240: 0b 50 00 10 10 10 [MMI] ld4 r10=[r8];;
246: 90 08 28 00 42 00 adds r9=1,r10
24c: 00 00 04 00 nop.i 0x0;;
250: 09 00 00 00 01 00 [MMI] nop.m 0x0
256: 00 48 20 20 23 00 st4 [r8]=r9
25c: 00 00 04 00 nop.i 0x0;;
260: 08 10 80 06 00 21 [MMI] adds r2=32,r3
266: 00 00 00 02 00 00 nop.m 0x0
26c: 02 08 f1 52 extr.u r16=r33,0,61
270: 05 40 88 00 08 e0 [MLX] addp4 r8=r34,r0
276: ff ff 0f 00 00 e0 movl r15=0xfffffffbfff;;
27c: f1 f7 ff 65
280: 09 70 00 04 18 10 [MMI] ld8 r14=[r2]
286: 00 00 00 02 00 c0 nop.m 0x0
28c: f0 80 1c d0 cmp.ltu p6,p7=r15,r16;;
290: 08 40 fc 1d 09 3b [MMI] cmp.eq p8,p9=-1,r14
296: 00 00 00 02 00 40 nop.m 0x0
29c: e1 08 2d d0 cmp.ltu p10,p11=r14,r33
2a0: 56 01 10 00 40 10 [BBB] (p10) br.cond.spnt.few 2e0
<cmpxchg_futex_value_locked+0xb0>
2a6: 02 08 00 80 21 03 (p08) br.cond.dpnt.few 2b0
<cmpxchg_futex_value_locked+0x80>
2ac: 40 00 00 41 (p06) br.cond.spnt.few 2e0
<cmpxchg_futex_value_locked+0xb0>
2b0: 0a 00 00 00 22 00 [MMI] mf;;
2b6: 80 00 00 00 42 00 mov r8=r0
2bc: 00 00 04 00 nop.i 0x0
2c0: 0b 00 20 40 2a 04 [MMI] mov.m ar.ccv=r8;;
2c6: 10 1a 85 22 20 00 cmpxchg4.acq r33=[r33],r35,ar.ccv
2cc: 00 00 04 00 nop.i 0x0;;
2d0: 10 00 84 40 90 11 [MIB] st4 [r32]=r33
2d6: 00 00 00 02 00 00 nop.i 0x0
2dc: 20 00 00 40 br.few 2f0
<cmpxchg_futex_value_locked+0xc0>
2e0: 09 40 c8 f9 ff 27 [MMI] mov r8=-14
2e6: 00 00 00 02 00 00 nop.m 0x0
2ec: 00 00 04 00 nop.i 0x0;;
2f0: 0b 58 20 1a 19 21 [MMI] adds r11=3208,r13;;
2f6: 20 01 2c 20 20 00 ld4 r18=[r11]
2fc: 00 00 04 00 nop.i 0x0;;
300: 0b 88 fc 25 3f 23 [MMI] adds r17=-1,r18;;
306: 00 88 2c 20 23 00 st4 [r11]=r17
30c: 00 00 04 00 nop.i 0x0;;
310: 11 00 00 00 01 00 [MIB] nop.m 0x0
316: 00 00 00 02 00 80 nop.i 0x0
31c: 08 00 84 00 br.ret.sptk.many b0;;
The lines
2b0: 0a 00 00 00 22 00 [MMI] mf;;
2b6: 80 00 00 00 42 00 mov r8=r0
2bc: 00 00 04 00 nop.i 0x0
2c0: 0b 00 20 40 2a 04 [MMI] mov.m ar.ccv=r8;;
2c6: 10 1a 85 22 20 00 cmpxchg4.acq r33=[r33],r35,ar.ccv
2cc: 00 00 04 00 nop.i 0x0;;
are the instructions of the assembly block.
The line
2b6: 80 00 00 00 42 00 mov r8=r0
sets the r8 register to 0 and after that
2c0: 0b 00 20 40 2a 04 [MMI] mov.m ar.ccv=r8;;
prepares the 'oldvalue' for the cmpxchg but it takes it from r8. This
is wrong.
What happened here is what I explained above: An input register is
overwritten which is still needed.
The register operand constraints in futex.h are wrong.
(The problem doesn't occur when the Kernel is compiled with GCC 4.6.)
The attached patch fixes the register operand constraints in futex.h.
The code after patching of it:
static inline int
futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
u32 oldval, u32 newval)
{
if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
return -EFAULT;
{
register unsigned long r8 __asm ("r8") = 0;
unsigned long prev;
__asm__ __volatile__(
" mf;; \n"
" mov ar.ccv=%4;; \n"
"[1:] cmpxchg4.acq %1=[%2],%3,ar.ccv \n"
" .xdata4 \"__ex_table\", 1b-., 2f-. \n"
"[2:]"
: "+r" (r8), "=&r" (prev)
: "r" (uaddr), "r" (newval),
"rO" ((long) (unsigned) oldval)
: "memory");
*uval = prev;
return r8;
}
}
I also initialized the 'r8' var with the C programming language.
The _asm qualifier on the definition of the 'r8' var forces GCC to use
the r8 processor register for it.
I don't believe that we should use inline assembly for zeroing out a
local variable.
The constraint is
"+r" (r8)
what means that it is both an input register and an output register.
Note that the page fault handler will modify the r8 register which
will be the return value of the function.
The real fix is
"=&r" (prev)
The & means that GCC must not use any of the input registers to place
this output register in.
Patched the Kernel 3.2.23 and compiled it with GCC4.4:
0000000000000230 <cmpxchg_futex_value_locked>:
230: 0b 18 80 1b 18 21 [MMI] adds r3=3168,r13;;
236: 80 40 0d 00 42 00 adds r8=40,r3
23c: 00 00 04 00 nop.i 0x0;;
240: 0b 50 00 10 10 10 [MMI] ld4 r10=[r8];;
246: 90 08 28 00 42 00 adds r9=1,r10
24c: 00 00 04 00 nop.i 0x0;;
250: 09 00 00 00 01 00 [MMI] nop.m 0x0
256: 00 48 20 20 23 00 st4 [r8]=r9
25c: 00 00 04 00 nop.i 0x0;;
260: 08 10 80 06 00 21 [MMI] adds r2=32,r3
266: 20 12 01 10 40 00 addp4 r34=r34,r0
26c: 02 08 f1 52 extr.u r16=r33,0,61
270: 05 40 00 00 00 e1 [MLX] mov r8=r0
276: ff ff 0f 00 00 e0 movl r15=0xfffffffbfff;;
27c: f1 f7 ff 65
280: 09 70 00 04 18 10 [MMI] ld8 r14=[r2]
286: 00 00 00 02 00 c0 nop.m 0x0
28c: f0 80 1c d0 cmp.ltu p6,p7=r15,r16;;
290: 08 40 fc 1d 09 3b [MMI] cmp.eq p8,p9=-1,r14
296: 00 00 00 02 00 40 nop.m 0x0
29c: e1 08 2d d0 cmp.ltu p10,p11=r14,r33
2a0: 56 01 10 00 40 10 [BBB] (p10) br.cond.spnt.few 2e0
<cmpxchg_futex_value_locked+0xb0>
2a6: 02 08 00 80 21 03 (p08) br.cond.dpnt.few 2b0
<cmpxchg_futex_value_locked+0x80>
2ac: 40 00 00 41 (p06) br.cond.spnt.few 2e0
<cmpxchg_futex_value_locked+0xb0>
2b0: 0b 00 00 00 22 00 [MMI] mf;;
2b6: 00 10 81 54 08 00 mov.m ar.ccv=r34
2bc: 00 00 04 00 nop.i 0x0;;
2c0: 09 58 8c 42 11 10 [MMI] cmpxchg4.acq r11=[r33],r35,ar.ccv
2c6: 00 00 00 02 00 00 nop.m 0x0
2cc: 00 00 04 00 nop.i 0x0;;
2d0: 10 00 2c 40 90 11 [MIB] st4 [r32]=r11
2d6: 00 00 00 02 00 00 nop.i 0x0
2dc: 20 00 00 40 br.few 2f0
<cmpxchg_futex_value_locked+0xc0>
2e0: 09 40 c8 f9 ff 27 [MMI] mov r8=-14
2e6: 00 00 00 02 00 00 nop.m 0x0
2ec: 00 00 04 00 nop.i 0x0;;
2f0: 0b 88 20 1a 19 21 [MMI] adds r17=3208,r13;;
2f6: 30 01 44 20 20 00 ld4 r19=[r17]
2fc: 00 00 04 00 nop.i 0x0;;
300: 0b 90 fc 27 3f 23 [MMI] adds r18=-1,r19;;
306: 00 90 44 20 23 00 st4 [r17]=r18
30c: 00 00 04 00 nop.i 0x0;;
310: 11 00 00 00 01 00 [MIB] nop.m 0x0
316: 00 00 00 02 00 80 nop.i 0x0
31c: 08 00 84 00 br.ret.sptk.many b0;;
Much better.
There is a
270: 05 40 00 00 00 e1 [MLX] mov r8=r0
which was generated by C code r8 = 0. Below
2b6: 00 10 81 54 08 00 mov.m ar.ccv=r34
what means that oldval is no longer overwritten.
This is Debian bug#702641
(http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=702641).
The patch is applicable on Kernel 3.9-rc1, 3.2.23 and many other versions.
Signed-off-by: Stephan Schreiber <info@fs-driver.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit d303e9e98fce56cdb3c6f2ac92f626fc2bd51c77 upstream. Back 2010 during a revamp of the irq code some initializations were moved from ia64_mca_init() to ia64_mca_late_init() in commit c75f2aa13f5b268aba369b5dc566088b5194377c Cannot use register_percpu_irq() from ia64_mca_init() But this was hideously wrong. First of all these initializations are now down far too late. Specifically after all the other cpus have been brought up and initialized their own CMC vectors from smp_callin(). Also ia64_mca_late_init() may be called from any cpu so the line: ia64_mca_cmc_vector_setup(); /* Setup vector on BSP */ is generally not executed on the BSP, and so the CMC vector isn't setup at all on that processor. Make use of the arch_early_irq_init() hook to get this code executed at just the right moment: not too early, not too late. Reported-by: Fred Hartnett <fred.hartnett@hp.com> Tested-by: Fred Hartnett <fred.hartnett@hp.com> Signed-off-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull vfs pile (part one) from Al Viro: "Assorted stuff - cleaning namei.c up a bit, fixing ->d_name/->d_parent locking violations, etc. The most visible changes here are death of FS_REVAL_DOT (replaced with "has ->d_weak_revalidate()") and a new helper getting from struct file to inode. Some bits of preparation to xattr method interface changes. Misc patches by various people sent this cycle *and* ocfs2 fixes from several cycles ago that should've been upstream right then. PS: the next vfs pile will be xattr stuff." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (46 commits) saner proc_get_inode() calling conventions proc: avoid extra pde_put() in proc_fill_super() fs: change return values from -EACCES to -EPERM fs/exec.c: make bprm_mm_init() static ocfs2/dlm: use GFP_ATOMIC inside a spin_lock ocfs2: fix possible use-after-free with AIO ocfs2: Fix oops in ocfs2_fast_symlink_readpage() code path get_empty_filp()/alloc_file() leave both ->f_pos and ->f_version zero target: writev() on single-element vector is pointless export kernel_write(), convert open-coded instances fs: encode_fh: return FILEID_INVALID if invalid fid_type kill f_vfsmnt vfs: kill FS_REVAL_DOT by adding a d_weak_revalidate dentry op nfsd: handle vfs_getattr errors in acl protocol switch vfs_getattr() to struct path default SET_PERSONALITY() in linux/elf.h ceph: prepopulate inodes only when request is aborted d_hash_and_lookup(): export, switch open-coded instances 9p: switch v9fs_set_create_acl() to inode+fid, do it before d_instantiate() 9p: split dropping the acls from v9fs_set_create_acl() ...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull KVM updates from Marcelo Tosatti: "KVM updates for the 3.9 merge window, including x86 real mode emulation fixes, stronger memory slot interface restrictions, mmu_lock spinlock hold time reduction, improved handling of large page faults on shadow, initial APICv HW acceleration support, s390 channel IO based virtio, amongst others" * tag 'kvm-3.9-1' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (143 commits) Revert "KVM: MMU: lazily drop large spte" x86: pvclock kvm: align allocation size to page size KVM: nVMX: Remove redundant get_vmcs12 from nested_vmx_exit_handled_msr x86 emulator: fix parity calculation for AAD instruction KVM: PPC: BookE: Handle alignment interrupts booke: Added DBCR4 SPR number KVM: PPC: booke: Allow multiple exception types KVM: PPC: booke: use vcpu reference from thread_struct KVM: Remove user_alloc from struct kvm_memory_slot KVM: VMX: disable apicv by default KVM: s390: Fix handling of iscs. KVM: MMU: cleanup __direct_map KVM: MMU: remove pt_access in mmu_set_spte KVM: MMU: cleanup mapping-level KVM: MMU: lazily drop large spte KVM: VMX: cleanup vmx_set_cr0(). KVM: VMX: add missing exit names to VMX_EXIT_REASONS array KVM: VMX: disable SMEP feature when guest is in non-paging mode KVM: Remove duplicate text in api.txt Revert "KVM: MMU: split kvm_mmu_free_page" ...
Pull signal handling cleanups from Al Viro:
"This is the first pile; another one will come a bit later and will
contain SYSCALL_DEFINE-related patches.
- a bunch of signal-related syscalls (both native and compat)
unified.
- a bunch of compat syscalls switched to COMPAT_SYSCALL_DEFINE
(fixing several potential problems with missing argument
validation, while we are at it)
- a lot of now-pointless wrappers killed
- a couple of architectures (cris and hexagon) forgot to save
altstack settings into sigframe, even though they used the
(uninitialized) values in sigreturn; fixed.
- microblaze fixes for delivery of multiple signals arriving at once
- saner set of helpers for signal delivery introduced, several
architectures switched to using those."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal: (143 commits)
x86: convert to ksignal
sparc: convert to ksignal
arm: switch to struct ksignal * passing
alpha: pass k_sigaction and siginfo_t using ksignal pointer
burying unused conditionals
make do_sigaltstack() static
arm64: switch to generic old sigaction() (compat-only)
arm64: switch to generic compat rt_sigaction()
arm64: switch compat to generic old sigsuspend
arm64: switch to generic compat rt_sigqueueinfo()
arm64: switch to generic compat rt_sigpending()
arm64: switch to generic compat rt_sigprocmask()
arm64: switch to generic sigaltstack
sparc: switch to generic old sigsuspend
sparc: COMPAT_SYSCALL_DEFINE does all sign-extension as well as SYSCALL_DEFINE
sparc: kill sign-extending wrappers for native syscalls
kill sparc32_open()
sparc: switch to use of generic old sigaction
sparc: switch sys_compat_rt_sigaction() to COMPAT_SYSCALL_DEFINE
mips: switch to generic sys_fork() and sys_clone()
...
Pull ACPI and power management updates from Rafael Wysocki: - Rework of the ACPI namespace scanning code from Rafael J. Wysocki with contributions from Bjorn Helgaas, Jiang Liu, Mika Westerberg, Toshi Kani, and Yinghai Lu. - ACPI power resources handling and ACPI device PM update from Rafael J Wysocki. - ACPICA update to version 20130117 from Bob Moore and Lv Zheng with contributions from Aaron Lu, Chao Guan, Jesper Juhl, and Tim Gardner. - Support for Intel Lynxpoint LPSS from Mika Westerberg. - cpuidle update from Len Brown including Intel Haswell support, C1 state for intel_idle, removal of global pm_idle. - cpuidle fixes and cleanups from Daniel Lezcano. - cpufreq fixes and cleanups from Viresh Kumar and Fabio Baltieri with contributions from Stratos Karafotis and Rickard Andersson. - Intel P-states driver for Sandy Bridge processors from Dirk Brandewie. - cpufreq driver for Marvell Kirkwood SoCs from Andrew Lunn. - cpufreq fixes related to ordering issues between acpi-cpufreq and powernow-k8 from Borislav Petkov and Matthew Garrett. - cpufreq support for Calxeda Highbank processors from Mark Langsdorf and Rob Herring. - cpufreq driver for the Freescale i.MX6Q SoC and cpufreq-cpu0 update from Shawn Guo. - cpufreq Exynos fixes and cleanups from Jonghwan Choi, Sachin Kamat, and Inderpal Singh. - Support for "lightweight suspend" from Zhang Rui. - Removal of the deprecated power trace API from Paul Gortmaker. - Assorted updates from Andreas Fleig, Colin Ian King, Davidlohr Bueso, Joseph Salisbury, Kees Cook, Li Fei, Nishanth Menon, ShuoX Liu, Srinivas Pandruvada, Tejun Heo, Thomas Renninger, and Yasuaki Ishimatsu. * tag 'pm+acpi-3.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (267 commits) PM idle: remove global declaration of pm_idle unicore32 idle: delete stray pm_idle comment openrisc idle: delete pm_idle mn10300 idle: delete pm_idle microblaze idle: delete pm_idle m32r idle: delete pm_idle, and other dead idle code ia64 idle: delete pm_idle cris idle: delete idle and pm_idle ARM64 idle: delete pm_idle ARM idle: delete pm_idle blackfin idle: delete pm_idle sparc idle: rename pm_idle to sparc_idle sh idle: rename global pm_idle to static sh_idle x86 idle: rename global pm_idle to static x86_idle APM idle: register apm_cpu_idle via cpuidle cpufreq / intel_pstate: Add kernel command line option disable intel_pstate. cpufreq / intel_pstate: Change to disallow module build tools/power turbostat: display SMI count by default intel_idle: export both C1 and C1E ACPI / hotplug: Fix concurrency issues and memory leaks ...
__ARCH_WANT_SYS_RT_SIGACTION,
__ARCH_WANT_SYS_RT_SIGSUSPEND,
__ARCH_WANT_COMPAT_SYS_RT_SIGSUSPEND,
__ARCH_WANT_COMPAT_SYS_SCHED_RR_GET_INTERVAL - not used anymore
CONFIG_GENERIC_{SIGALTSTACK,COMPAT_RT_SIG{ACTION,QUEUEINFO,PENDING,PROCMASK}} -
can be assumed always set.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Only alpha and sparc are unusual - they have ka_restorer in it. And nobody needs that exposed to userland. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>