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  1. 08 Feb, 2016 3 commits
    • Kees Cook's avatar
      ARM: 8501/1: mm: flip priority of CONFIG_DEBUG_RODATA · 25362dc4
      Kees Cook authored 
      The use of CONFIG_DEBUG_RODATA is generally seen as an essential part of
kernel self-protection:
http://www.openwall.com/lists/kernel-hardening/2015/11/30/13
Additionally, its name has grown to mean things beyond just rodata. To
get ARM closer to this, we ought to rearrange the names of the configs
that control how the kernel protects its memory. What was called
CONFIG_ARM_KERNMEM_PERMS is realy doing the work that other architectures
call CONFIG_DEBUG_RODATA.

This redefines CONFIG_DEBUG_RODATA to actually do the bulk of the
ROing (and NXing). In the place of the old CONFIG_DEBUG_RODATA, use
CONFIG_DEBUG_ALIGN_RODATA, since that's what the option does: adds
section alignment for making rodata explicitly NX, as arm does not split
the page tables like arm64 does without _ALIGN_RODATA.

Also adds human readable names to the sections so I could more easily
debug my typos, and makes CONFIG_DEBUG_RODATA default "y" for CPU_V7.

Results in /sys/kernel/debug/kernel_page_tables for each config state:

 # CONFIG_DEBUG_RODATA is not set
 # CONFIG_DEBUG_ALIGN_RODATA is not set

---[ Kernel Mapping ]---
0x80000000-0x80900000           9M     RW x  SHD
0x80900000-0xa0000000         503M     RW NX SHD

 CONFIG_DEBUG_RODATA=y
 CONFIG_DEBUG_ALIGN_RODATA=y

---[ Kernel Mapping ]---
0x80000000-0x80100000           1M     RW NX SHD
0x80100000-0x80700000           6M     ro x  SHD
0x80700000-0x80a00000           3M     ro NX SHD
0x80a00000-0xa0000000         502M     RW NX SHD

 CONFIG_DEBUG_RODATA=y
 # CONFIG_DEBUG_ALIGN_RODATA is not set

---[ Kernel Mapping ]---
0x80000000-0x80100000           1M     RW NX SHD
0x80100000-0x80a00000           9M     ro x  SHD
0x80a00000-0xa0000000         502M     RW NX SHD
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarLaura Abbott <labbott@fedoraproject.org>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
      25362dc4
    • Russell King's avatar
      ARM: use virt_to_idmap() for soft_restart() · 4138323e
      Russell King authored 
      Code run via soft_restart() is run with the MMU disabled, so we need to
pass the identity map physical address rather than the address obtained
from virt_to_phys().  Therefore, replace virt_to_phys() with
virt_to_idmap() for all callers of soft_restart().
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
      4138323e
    • Russell King's avatar
      ARM: make virt_to_idmap() return unsigned long · 28410293
      Russell King authored 
      Make virt_to_idmap() return an unsigned long rather than phys_addr_t.

Returning phys_addr_t here makes no sense, because the definition of
virt_to_idmap() is that it shall return a physical address which maps
identically with the virtual address.  Since virtual addresses are
limited to 32-bit, identity mapped physical addresses are as well.

Almost all users already had an implicit narrowing cast to unsigned long
so let's make this official and part of this interface.
Tested-by: default avatarGrygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
      28410293
  3. 26 Jan, 2016 3 commits
  5. 24 Jan, 2016 34 commits
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