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  1. 13 7月, 2017 3 次提交
  3. 04 7月, 2017 1 次提交
    • B
      powerpc/Kconfig: Enable STRICT_KERNEL_RWX for some configs · 1e0fc9d1
      由 Balbir Singh 提交于 
      All code that patches kernel text has been moved over to using
patch_instruction() and patch_instruction() is able to cope with the
kernel text being read only.

The linker script has been updated to ensure the read only data ends
on a large page boundary, so it and the preceding kernel text can be
marked R_X. We also have implementations of mark_rodata_ro() for Hash
and Radix MMU modes.

There are some corner-cases missing when the kernel is built
relocatable, so for now make it depend on !RELOCATABLE.

There's also a temporary workaround to depend on !HIBERNATION to avoid
a build failure, that will be removed once we've merged with the PM
tree.
Signed-off-by: NBalbir Singh <bsingharora@gmail.com>
[mpe: Make it depend on !RELOCATABLE, munge change log]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      1e0fc9d1
  5. 02 7月, 2017 1 次提交
  7. 30 6月, 2017 1 次提交
  9. 22 6月, 2017 1 次提交
    • P
      powerpc: Convert VDSO update function to use new update_vsyscall interface · d4cfb113
      由 Paul Mackerras 提交于 
      This converts the powerpc VDSO time update function to use the new
interface introduced in commit 576094b7 ("time: Introduce new
GENERIC_TIME_VSYSCALL", 2012-09-11).  Where the old interface gave
us the time as of the last update in seconds and whole nanoseconds,
with the new interface we get the nanoseconds part effectively in
a binary fixed-point format with tk->tkr_mono.shift bits to the
right of the binary point.

With the old interface, the fractional nanoseconds got truncated,
meaning that the value returned by the VDSO clock_gettime function
would have about 1ns of jitter in it compared to the value computed
by the generic timekeeping code in the kernel.

The powerpc VDSO time functions (clock_gettime and gettimeofday)
already work in units of 2^-32 seconds, or 0.23283 ns, because that
makes it simple to split the result into seconds and fractional
seconds, and represent the fractional seconds in either microseconds
or nanoseconds.  This is good enough accuracy for now, so this patch
avoids changing how the VDSO works or the interface in the VDSO data
page.

This patch converts the powerpc update_vsyscall_old to be called
update_vsyscall and use the new interface.  We convert the fractional
second to units of 2^-32 seconds without truncating to whole nanoseconds.
(There is still a conversion to whole nanoseconds for any legacy users
of the vdso_data/systemcfg stamp_xtime field.)

In addition, this improves the accuracy of the computation of tb_to_xs
for those systems with high-frequency timebase clocks (>= 268.5 MHz)
by doing the right shift in two parts, one before the multiplication and
one after, rather than doing the right shift before the multiplication.
(We can't do all of the right shift after the multiplication unless we
use 128-bit arithmetic.)
Signed-off-by: NPaul Mackerras <paulus@ozlabs.org>
Acked-by: NJohn Stultz <john.stultz@linaro.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      d4cfb113
  11. 13 6月, 2017 1 次提交
  13. 09 6月, 2017 1 次提交
  15. 08 6月, 2017 1 次提交
    • M
      powerpc/book3s64: Move PPC_DT_CPU_FTRs and enable it by default · c6ee9619
      由 Michael Ellerman 提交于 
      The PPC_DT_CPU_FTRs is a bit misplaced in menuconfig, it shows up with
other general kernel options. It's really more at home in the "Platform
Support" section, so move it there.

Also enable it by default, for Book3s 64. It does mostly nothing unless
the device tree properties are found, and we will want it enabled
eventually in distro kernels, so turn it on to start getting more
testing.

Fixes: 5a61ef74 ("powerpc/64s: Support new device tree binding for discovering CPU features")
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      c6ee9619
  17. 02 6月, 2017 1 次提交
    • C
      powerpc: Remove __ilog2()s and use generic ones · f782ddf2
      由 Christophe Leroy 提交于 
      With the __ilog2() function as defined in
arch/powerpc/include/asm/bitops.h, GCC will not optimise the code
in case of constant parameter.

The generic ilog2() function in include/linux/log2.h is written
to handle the case of the constant parameter.

This patch discards the three __ilog2() functions and
defines __ilog2() as ilog2()

For non constant calls, the generated code is doing the same:
int test__ilog2(unsigned long x)
{
	return __ilog2(x);
}

int test__ilog2_u32(u32 n)
{
	return __ilog2_u32(n);
}

int test__ilog2_u64(u64 n)
{
	return __ilog2_u64(n);
}

On PPC32 before the patch:
00000000 <test__ilog2>:
   0:	7c 63 00 34 	cntlzw  r3,r3
   4:	20 63 00 1f 	subfic  r3,r3,31
   8:	4e 80 00 20 	blr

0000000c <test__ilog2_u32>:
   c:	7c 63 00 34 	cntlzw  r3,r3
  10:	20 63 00 1f 	subfic  r3,r3,31
  14:	4e 80 00 20 	blr

On PPC32 after the patch:
00000000 <test__ilog2>:
   0:	7c 63 00 34 	cntlzw  r3,r3
   4:	20 63 00 1f 	subfic  r3,r3,31
   8:	4e 80 00 20 	blr

0000000c <test__ilog2_u32>:
   c:	7c 63 00 34 	cntlzw  r3,r3
  10:	20 63 00 1f 	subfic  r3,r3,31
  14:	4e 80 00 20 	blr

On PPC64 before the patch:
0000000000000000 <.test__ilog2>:
   0:	7c 63 00 74 	cntlzd  r3,r3
   4:	20 63 00 3f 	subfic  r3,r3,63
   8:	7c 63 07 b4 	extsw   r3,r3
   c:	4e 80 00 20 	blr

0000000000000010 <.test__ilog2_u32>:
  10:	7c 63 00 34 	cntlzw  r3,r3
  14:	20 63 00 1f 	subfic  r3,r3,31
  18:	7c 63 07 b4 	extsw   r3,r3
  1c:	4e 80 00 20 	blr

0000000000000020 <.test__ilog2_u64>:
  20:	7c 63 00 74 	cntlzd  r3,r3
  24:	20 63 00 3f 	subfic  r3,r3,63
  28:	7c 63 07 b4 	extsw   r3,r3
  2c:	4e 80 00 20 	blr

On PPC64 after the patch:
0000000000000000 <.test__ilog2>:
   0:	7c 63 00 74 	cntlzd  r3,r3
   4:	20 63 00 3f 	subfic  r3,r3,63
   8:	7c 63 07 b4 	extsw   r3,r3
   c:	4e 80 00 20 	blr

0000000000000010 <.test__ilog2_u32>:
  10:	7c 63 00 34 	cntlzw  r3,r3
  14:	20 63 00 1f 	subfic  r3,r3,31
  18:	7c 63 07 b4 	extsw   r3,r3
  1c:	4e 80 00 20 	blr

0000000000000020 <.test__ilog2_u64>:
  20:	7c 63 00 74 	cntlzd  r3,r3
  24:	20 63 00 3f 	subfic  r3,r3,63
  28:	7c 63 07 b4 	extsw   r3,r3
  2c:	4e 80 00 20 	blr
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      f782ddf2
  19. 01 6月, 2017 1 次提交
  21. 30 5月, 2017 2 次提交
    • N
      powerpc/64: Handle linker stubs in low .text code · 951eedeb
      由 Nicholas Piggin 提交于 
      Very large kernels may require linker stubs for branches from HEAD
text code. The linker may place these stubs before the HEAD text
sections, which breaks the assumption that HEAD text is located at 0
(or the .text section being located at 0x7000/0x8000 on Book3S
kernels).

Provide an option to create a small section just before the .text
section with an empty 256 - 4 bytes, and adjust the start of the .text
section to match. The linker will tend to put stubs in that section
and not break our relative-to-absolute offset assumptions.

This causes a small waste of space on common kernels, but allows large
kernels to build and boot. For now, it is an EXPERT config option,
defaulting to =n, but a reference is provided for it in the build-time
check for such breakage. This is good enough for allyesconfig and
custom users / hackers.
Signed-off-by: NNicholas Piggin <npiggin@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      951eedeb
    • A
      powerpc: Add HAVE_IRQ_TIME_ACCOUNTING · 518470fe
      由 Anton Blanchard 提交于 
      Allow us to enable IRQ_TIME_ACCOUNTING. Even though we currently
use VIRT_CPU_ACCOUNTING_NATIVE, that option is quite heavy
weight and IRQ_TIME_ACCOUNTING might be better in some cases.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      518470fe
  23. 09 5月, 2017 2 次提交
  25. 01 5月, 2017 1 次提交
  27. 28 4月, 2017 1 次提交
  29. 27 4月, 2017 2 次提交
  31. 24 4月, 2017 1 次提交
  33. 23 4月, 2017 1 次提交
    • I
      Revert "x86/mm/gup: Switch GUP to the generic get_user_page_fast() implementation" · 6dd29b3d
      由 Ingo Molnar 提交于 
      This reverts commit 2947ba05.

Dan Williams reported dax-pmem kernel warnings with the following signature:

   WARNING: CPU: 8 PID: 245 at lib/percpu-refcount.c:155 percpu_ref_switch_to_atomic_rcu+0x1f5/0x200
   percpu ref (dax_pmem_percpu_release [dax_pmem]) <= 0 (0) after switching to atomic

... and bisected it to this commit, which suggests possible memory corruption
caused by the x86 fast-GUP conversion.

He also pointed out:

 "
  This is similar to the backtrace when we were not properly handling
  pud faults and was fixed with this commit: 220ced16 "mm: fix
  get_user_pages() vs device-dax pud mappings"

  I've found some missing _devmap checks in the generic
  get_user_pages_fast() path, but this does not fix the regression
  [...]
 "

So given that there are known bugs, and a pretty robust looking bisection
points to this commit suggesting that are unknown bugs in the conversion
as well, revert it for the time being - we'll re-try in v4.13.
Reported-by: NDan Williams <dan.j.williams@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: aneesh.kumar@linux.vnet.ibm.com
Cc: dann.frazier@canonical.com
Cc: dave.hansen@intel.com
Cc: steve.capper@linaro.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      6dd29b3d
  35. 21 4月, 2017 1 次提交
    • M
      powerpc/mm: Add support for runtime configuration of ASLR limits · 9fea59bd
      由 Michael Ellerman 提交于 
      Add powerpc support for mmap_rnd_bits and mmap_rnd_compat_bits, which are two
sysctls that allow a user to configure the number of bits of randomness used for
ASLR.

Because of the way the Kconfig for ARCH_MMAP_RND_BITS is defined, we have to
construct at least the MIN value in Kconfig, vs in a header which would be more
natural. Given that we just go ahead and do it all in Kconfig.

At least according to the code (the documentation makes no mention of it), the
value is defined as the number of bits of randomisation *of the page*, not the
address. This makes some sense, with larger page sizes more of the low bits are
forced to zero, which would reduce the randomisation if we didn't take the
PAGE_SIZE into account. However it does mean the min/max values have to change
depending on the PAGE_SIZE in order to actually limit the amount of address
space consumed by the randomisation.

The result of that is that we have to define the default values based on both
32-bit vs 64-bit, but also the configured PAGE_SIZE. Furthermore now that we
have 128TB address space support on Book3S, we also have to take that into
account.

Finally we can wire up the value in arch_mmap_rnd().
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NBhupesh Sharma <bhsharma@redhat.com>
Tested-by: NBhupesh Sharma <bhsharma@redhat.com>
Reviewed-by: NKees Cook <keescook@chromium.org>
Reviewed-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
      9fea59bd
  37. 19 4月, 2017 1 次提交
  39. 11 4月, 2017 1 次提交
  41. 07 4月, 2017 1 次提交
  43. 20 3月, 2017 1 次提交
  45. 18 3月, 2017 1 次提交
  47. 06 3月, 2017 1 次提交
    • M
      powerpc: Sort the selects under CONFIG_PPC · a7d2475a
      由 Michael Ellerman 提交于 
      We have a big list of selects under CONFIG_PPC, and currently they're
completely unsorted. This means people tend to add new selects at the
bottom of the list, and so two commits which both add a new select will
often conflict.

Instead sort it alphabetically. This is nicer in and of itself, but also
means two commits that add a new select will have a greater chance of
not conflicting.

Add a note at the top and bottom asking people to keep it sorted.

And while we're here pad out the 'if' expressions to make them stand
out.
Suggested-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      a7d2475a
  49. 10 2月, 2017 2 次提交
    • A
      powerpc/ftrace: Fix confusing help text for DISABLE_MPROFILE_KERNEL · 496e9cb5
      由 Anton Blanchard 提交于 
      The final paragraph of the help text is reversed. We want to enable
this option by default, and disable it if the toolchain has a working
-mprofile-kernel.

Fixes: 8c50b72a ("powerpc/ftrace: Add Kconfig & Make glue for mprofile-kernel")
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      496e9cb5
    • A
      powerpc/kprobes: Implement Optprobes · 51c9c084
      由 Anju T 提交于 
      Current infrastructure of kprobe uses the unconditional trap instruction
to probe a running kernel. Optprobe allows kprobe to replace the trap
with a branch instruction to a detour buffer. Detour buffer contains
instructions to create an in memory pt_regs. Detour buffer also has a
call to optimized_callback() which in turn call the pre_handler(). After
the execution of the pre-handler, a call is made for instruction
emulation. The NIP is determined in advanced through dummy instruction
emulation and a branch instruction is created to the NIP at the end of
the trampoline.

To address the limitation of branch instruction in POWER architecture,
detour buffer slot is allocated from a reserved area. For the time
being, 64KB is reserved in memory for this purpose.

Instructions which can be emulated using analyse_instr() are the
candidates for optimization. Before optimization ensure that the address
range between the detour buffer allocated and the instruction being
probed is within +/- 32MB.
Signed-off-by: NAnju T Sudhakar <anju@linux.vnet.ibm.com>
Signed-off-by: NNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: NMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      51c9c084
  51. 04 2月, 2017 1 次提交
    • A
      modversions: treat symbol CRCs as 32 bit quantities · 71810db2
      由 Ard Biesheuvel 提交于 
      The modversion symbol CRCs are emitted as ELF symbols, which allows us
to easily populate the kcrctab sections by relying on the linker to
associate each kcrctab slot with the correct value.

This has a couple of downsides:

 - Given that the CRCs are treated as memory addresses, we waste 4 bytes
   for each CRC on 64 bit architectures,

 - On architectures that support runtime relocation, a R_<arch>_RELATIVE
   relocation entry is emitted for each CRC value, which identifies it
   as a quantity that requires fixing up based on the actual runtime
   load offset of the kernel. This results in corrupted CRCs unless we
   explicitly undo the fixup (and this is currently being handled in the
   core module code)

 - Such runtime relocation entries take up 24 bytes of __init space
   each, resulting in a x8 overhead in [uncompressed] kernel size for
   CRCs.

Switching to explicit 32 bit values on 64 bit architectures fixes most
of these issues, given that 32 bit values are not treated as quantities
that require fixing up based on the actual runtime load offset.  Note
that on some ELF64 architectures [such as PPC64], these 32-bit values
are still emitted as [absolute] runtime relocatable quantities, even if
the value resolves to a build time constant.  Since relative relocations
are always resolved at build time, this patch enables MODULE_REL_CRCS on
powerpc when CONFIG_RELOCATABLE=y, which turns the absolute CRC
references into relative references into .rodata where the actual CRC
value is stored.

So redefine all CRC fields and variables as u32, and redefine the
__CRC_SYMBOL() macro for 64 bit builds to emit the CRC reference using
inline assembler (which is necessary since 64-bit C code cannot use
32-bit types to hold memory addresses, even if they are ultimately
resolved using values that do not exceed 0xffffffff).  To avoid
potential problems with legacy 32-bit architectures using legacy
toolchains, the equivalent C definition of the kcrctab entry is retained
for 32-bit architectures.

Note that this mostly reverts commit d4703aef ("module: handle ppc64
relocating kcrctabs when CONFIG_RELOCATABLE=y")
Acked-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      71810db2
  53. 03 2月, 2017 1 次提交
  55. 02 2月, 2017 1 次提交
  57. 25 1月, 2017 3 次提交
    • C
      powerpc/8xx: Implement hw_breakpoint · 4ad8622d
      由 Christophe Leroy 提交于 
      This patch implements HW breakpoint on the 8xx. The 8xx has
capability to manage HW breakpoints, which is slightly different
than BOOK3S:
1/ The breakpoint match doesn't trigger a DSI exception but a
dedicated data breakpoint exception.
2/ The breakpoint happens after the instruction has completed,
no need to single step or emulate the instruction,
3/ Matched address is not set in DAR but in BAR,
4/ DABR register doesn't exist, instead we have registers
LCTRL1, LCTRL2 and CMPx registers,
5/ The match on one comparator is not on a double word but
on a single word.

The patch does:
1/ Prepare the dedicated registers in call to __set_dabr(). In order
to emulate the double word handling of BOOK3S, comparator E is set to
DABR address value and comparator F to address + 4. Then breakpoint 1
is set to match comparator E or F,
2/ Skip the singlestepping stage when compiled for CONFIG_PPC_8xx,
3/ Implement the exception. In that exception, the matched address
is taken from SPRN_BAR and manage as if it was from SPRN_DAR.
4/ I/D TLB error exception routines perform a tlbie on bad TLBs. That
tlbie triggers the breakpoint exception when performed on the
breakpoint address. For this reason, the routine returns if the match
is from one of those two tlbie.
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: NScott Wood <oss@buserror.net>
      4ad8622d
    • C
      powerpc/32: Enable HW_BREAKPOINT on BOOK3S · fa769d3f
      由 Christophe Leroy 提交于 
      BOOK3S also has DABR register and capability to handle data
breakpoints, so this patch enable it on all BOOK3S, not only 64 bits.
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: NScott Wood <oss@buserror.net>
      fa769d3f
    • P
      powerpc/64: Use optimized checksum routines on little-endian · d4fde568
      由 Paul Mackerras 提交于 
      Currently we have optimized hand-coded assembly checksum routines for
big-endian 64-bit systems, but for little-endian we use the generic C
routines. This modifies the optimized routines to work for
little-endian. With this, we no longer need to enable
CONFIG_GENERIC_CSUM. This also fixes a couple of comments in
checksum_64.S so they accurately reflect what the associated instruction
does.
Signed-off-by: NPaul Mackerras <paulus@ozlabs.org>
[mpe: Use the more common __BIG_ENDIAN__]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      d4fde568
  59. 24 1月, 2017 1 次提交
    • M
      powerpc: Revert the initial stack protector support · f2574030
      由 Michael Ellerman 提交于 
      Unfortunately the stack protector support we merged recently only works
on some toolchains. If the toolchain is built without glibc support
everything works fine, but if glibc is built then it leads to a panic
at boot.

The solution is not rc5 material, so revert the support for now. This
reverts commits:

6533b7c1 ("powerpc: Initial stack protector (-fstack-protector) support")
902e06eb ("powerpc/32: Change the stack protector canary value per task")

Fixes: 6533b7c1 ("powerpc: Initial stack protector (-fstack-protector) support")
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      f2574030
  61. 21 12月, 2016 1 次提交
    • T
      powerpc: ima: get the kexec buffer passed by the previous kernel · 467d2782
      由 Thiago Jung Bauermann 提交于 
      Patch series "ima: carry the measurement list across kexec", v8.

The TPM PCRs are only reset on a hard reboot.  In order to validate a
TPM's quote after a soft reboot (eg.  kexec -e), the IMA measurement
list of the running kernel must be saved and then restored on the
subsequent boot, possibly of a different architecture.

The existing securityfs binary_runtime_measurements file conveniently
provides a serialized format of the IMA measurement list.  This patch
set serializes the measurement list in this format and restores it.

Up to now, the binary_runtime_measurements was defined as architecture
native format.  The assumption being that userspace could and would
handle any architecture conversions.  With the ability of carrying the
measurement list across kexec, possibly from one architecture to a
different one, the per boot architecture information is lost and with it
the ability of recalculating the template digest hash.  To resolve this
problem, without breaking the existing ABI, this patch set introduces
the boot command line option "ima_canonical_fmt", which is arbitrarily
defined as little endian.

The need for this boot command line option will be limited to the
existing version 1 format of the binary_runtime_measurements.
Subsequent formats will be defined as canonical format (eg.  TPM 2.0
support for larger digests).

A simplified method of Thiago Bauermann's "kexec buffer handover" patch
series for carrying the IMA measurement list across kexec is included in
this patch set.  The simplified method requires all file measurements be
taken prior to executing the kexec load, as subsequent measurements will
not be carried across the kexec and restored.

This patch (of 10):

The IMA kexec buffer allows the currently running kernel to pass the
measurement list via a kexec segment to the kernel that will be kexec'd.
The second kernel can check whether the previous kernel sent the buffer
and retrieve it.

This is the architecture-specific part which enables IMA to receive the
measurement list passed by the previous kernel.  It will be used in the
next patch.

The change in machine_kexec_64.c is to factor out the logic of removing
an FDT memory reservation so that it can be used by remove_ima_buffer.

Link: http://lkml.kernel.org/r/1480554346-29071-2-git-send-email-zohar@linux.vnet.ibm.comSigned-off-by: NThiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Signed-off-by: NMimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andreas Steffen <andreas.steffen@strongswan.org>
Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
Cc: Josh Sklar <sklar@linux.vnet.ibm.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stewart Smith <stewart@linux.vnet.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      467d2782
  63. 02 12月, 2016 1 次提交
    • M
      powerpc/64: Define ILLEGAL_POINTER_VALUE for 64-bit · f6853eb5
      由 Michael Ellerman 提交于 
      This is used in poison.h to offset poison values so that they don't
point directly into user space.

The value we choose sits roughly between user and kernel space, which
means on their own the poison values don't point anywhere useful. If an
attacker can cause an access at some offset from the poison value then
we may still be in trouble, but by putting the poison values between
user and kernel space we maximise the required size of that offset.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      f6853eb5