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  1. 08 3月, 2017 1 次提交
  3. 01 3月, 2017 1 次提交
    • P
      KVM: PPC: Book3S HV: Fix software walk of guest process page tables · 70cd4c10
      由 Paul Mackerras 提交于 
      This fixes some bugs in the code that walks the guest's page tables.
These bugs cause MMIO emulation to fail whenever the guest is in
virtial mode (MMU on), leading to the guest hanging if it tried to
access a virtio device.

The first bug was that when reading the guest's process table, we were
using the whole of arch->process_table, not just the field that contains
the process table base address.  The second bug was that the mask used
when reading the process table entry to get the radix tree base address,
RPDB_MASK, had the wrong value.

Fixes: 9e04ba69 ("KVM: PPC: Book3S HV: Add basic infrastructure for radix guests")
Fixes: e9983344 ("powerpc/mm/radix: Add partition table format & callback")
Signed-off-by: NPaul Mackerras <paulus@ozlabs.org>
      70cd4c10
  5. 28 2月, 2017 2 次提交
  7. 25 2月, 2017 1 次提交
  9. 23 2月, 2017 1 次提交
    • D
      powerpc: do not make the entire heap executable · 16e72e9b
      由 Denys Vlasenko 提交于 
      On 32-bit powerpc the ELF PLT sections of binaries (built with
--bss-plt, or with a toolchain which defaults to it) look like this:

  [17] .sbss             NOBITS          0002aff8 01aff8 000014 00  WA  0   0  4
  [18] .plt              NOBITS          0002b00c 01aff8 000084 00 WAX  0   0  4
  [19] .bss              NOBITS          0002b090 01aff8 0000a4 00  WA  0   0  4

Which results in an ELF load header:

  Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
  LOAD           0x019c70 0x00029c70 0x00029c70 0x01388 0x014c4 RWE 0x10000

This is all correct, the load region containing the PLT is marked as
executable.  Note that the PLT starts at 0002b00c but the file mapping
ends at 0002aff8, so the PLT falls in the 0 fill section described by
the load header, and after a page boundary.

Unfortunately the generic ELF loader ignores the X bit in the load
headers when it creates the 0 filled non-file backed mappings.  It
assumes all of these mappings are RW BSS sections, which is not the case
for PPC.

gcc/ld has an option (--secure-plt) to not do this, this is said to
incur a small performance penalty.

Currently, to support 32-bit binaries with PLT in BSS kernel maps
*entire brk area* with executable rights for all binaries, even
--secure-plt ones.

Stop doing that.

Teach the ELF loader to check the X bit in the relevant load header and
create 0 filled anonymous mappings that are executable if the load
header requests that.

Test program showing the difference in /proc/$PID/maps:

int main() {
	char buf[16*1024];
	char *p = malloc(123); /* make "[heap]" mapping appear */
	int fd = open("/proc/self/maps", O_RDONLY);
	int len = read(fd, buf, sizeof(buf));
	write(1, buf, len);
	printf("%p\n", p);
	return 0;
}

Compiled using: gcc -mbss-plt -m32 -Os test.c -otest

Unpatched ppc64 kernel:
00100000-00120000 r-xp 00000000 00:00 0                                  [vdso]
0fe10000-0ffd0000 r-xp 00000000 fd:00 67898094                           /usr/lib/libc-2.17.so
0ffd0000-0ffe0000 r--p 001b0000 fd:00 67898094                           /usr/lib/libc-2.17.so
0ffe0000-0fff0000 rw-p 001c0000 fd:00 67898094                           /usr/lib/libc-2.17.so
10000000-10010000 r-xp 00000000 fd:00 100674505                          /home/user/test
10010000-10020000 r--p 00000000 fd:00 100674505                          /home/user/test
10020000-10030000 rw-p 00010000 fd:00 100674505                          /home/user/test
10690000-106c0000 rwxp 00000000 00:00 0                                  [heap]
f7f70000-f7fa0000 r-xp 00000000 fd:00 67898089                           /usr/lib/ld-2.17.so
f7fa0000-f7fb0000 r--p 00020000 fd:00 67898089                           /usr/lib/ld-2.17.so
f7fb0000-f7fc0000 rw-p 00030000 fd:00 67898089                           /usr/lib/ld-2.17.so
ffa90000-ffac0000 rw-p 00000000 00:00 0                                  [stack]
0x10690008

Patched ppc64 kernel:
00100000-00120000 r-xp 00000000 00:00 0                                  [vdso]
0fe10000-0ffd0000 r-xp 00000000 fd:00 67898094                           /usr/lib/libc-2.17.so
0ffd0000-0ffe0000 r--p 001b0000 fd:00 67898094                           /usr/lib/libc-2.17.so
0ffe0000-0fff0000 rw-p 001c0000 fd:00 67898094                           /usr/lib/libc-2.17.so
10000000-10010000 r-xp 00000000 fd:00 100674505                          /home/user/test
10010000-10020000 r--p 00000000 fd:00 100674505                          /home/user/test
10020000-10030000 rw-p 00010000 fd:00 100674505                          /home/user/test
10180000-101b0000 rw-p 00000000 00:00 0                                  [heap]
                  ^^^^ this has changed
f7c60000-f7c90000 r-xp 00000000 fd:00 67898089                           /usr/lib/ld-2.17.so
f7c90000-f7ca0000 r--p 00020000 fd:00 67898089                           /usr/lib/ld-2.17.so
f7ca0000-f7cb0000 rw-p 00030000 fd:00 67898089                           /usr/lib/ld-2.17.so
ff860000-ff890000 rw-p 00000000 00:00 0                                  [stack]
0x10180008

The patch was originally posted in 2012 by Jason Gunthorpe
and apparently ignored:

https://lkml.org/lkml/2012/9/30/138

Lightly run-tested.

Link: http://lkml.kernel.org/r/20161215131950.23054-1-dvlasenk@redhat.comSigned-off-by: NJason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: NDenys Vlasenko <dvlasenk@redhat.com>
Acked-by: NKees Cook <keescook@chromium.org>
Acked-by: NMichael Ellerman <mpe@ellerman.id.au>
Tested-by: NJason Gunthorpe <jgunthorpe@obsidianresearch.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Florian Weimer <fweimer@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      16e72e9b
  11. 21 2月, 2017 1 次提交
    • M
      powerpc/pseries: Advertise Hot Plug Event support to firmware · 3dbbaf20
      由 Michael Roth 提交于 
      With the inclusion of commit 333f7b76 ("powerpc/pseries: Implement
indexed-count hotplug memory add") and commit 75384347
("powerpc/pseries: Implement indexed-count hotplug memory remove"), we
now have complete handling of the RTAS hotplug event format as described
by PAPR via ACR "PAPR Changes for Hotplug RTAS Events".

This capability is indicated by byte 6, bit 2 (5 in IBM numbering) of
architecture option vector 5, and allows for greater control over
cpu/memory/pci hot plug/unplug operations.

Existing pseries kernels will utilize this capability based on the
existence of the /event-sources/hot-plug-events DT property, so we
only need to advertise it via CAS and do not need a corresponding
FW_FEATURE_* value to test for.
Signed-off-by: NMichael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      3dbbaf20
  13. 18 2月, 2017 1 次提交
    • N
      powerpc/64: Implement clear_bit_unlock_is_negative_byte() · d11914b2
      由 Nicholas Piggin 提交于 
      Commit b91e1302 ("mm: optimize PageWaiters bit use for
unlock_page()") added a special bitop function to speed up
unlock_page(). Implement this for 64-bit powerpc.

This improves the unlock_page() core code from this:

	li	9,1
	lwsync
1:	ldarx	10,0,3,0
	andc	10,10,9
	stdcx.	10,0,3
	bne-	1b
	ori	2,2,0
	ld	9,0(3)
	andi.	10,9,0x80
	beqlr
	li	4,0
	b	wake_up_page_bit

To this:

	li	10,1
	lwsync
1:	ldarx	9,0,3,0
	andc	9,9,10
	stdcx.	9,0,3
	bne-	1b
	andi.	10,9,0x80
	beqlr
	li	4,0
	b	wake_up_page_bit

In a test of elapsed time for dd writing into 16GB of already-dirty
pagecache on a POWER8 with 4K pages, which has one unlock_page per 4kB
this patch reduced overhead by 1.1%:

    N           Min           Max        Median           Avg        Stddev
x  19         2.578         2.619         2.594         2.595         0.011
+  19         2.552         2.592         2.564         2.565         0.008
Difference at 95.0% confidence
	-0.030  +/- 0.006
	-1.142% +/- 0.243%
Signed-off-by: NNicholas Piggin <npiggin@gmail.com>
[mpe: Made 64-bit only until I can test it properly on 32-bit]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      d11914b2
  15. 17 2月, 2017 1 次提交
  17. 15 2月, 2017 5 次提交
  19. 14 2月, 2017 1 次提交
  21. 10 2月, 2017 8 次提交
  23. 09 2月, 2017 2 次提交
  25. 07 2月, 2017 5 次提交
  27. 06 2月, 2017 6 次提交
  29. 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
  31. 02 2月, 2017 3 次提交