linux.git/arch/arm/kernel/head-common.S, branch v5.14

Merge branch 'devel-stable' into for-next

2020-12-21T11:19:26+00:00

ARM: head-common.S: use PC-relative insn sequence for __proc_info

2020-10-28T16:05:39+00:00

Replace the open coded PC relative offset calculations with a pair of
adr_l invocations. This removes some open coded arithmetic involving
virtual addresses, avoids literal pools on v7+, and slightly reduces
the footprint of the code.

Reviewed-by: Nicolas Pitre 
Signed-off-by: Ard Biesheuvel

ARM: 9016/2: Initialize the mapping of KASan shadow memory

2020-10-27T12:11:10+00:00

This patch initializes KASan shadow region's page table and memory.
There are two stage for KASan initializing:

1. At early boot stage the whole shadow region is mapped to just
   one physical page (kasan_zero_page). It is finished by the function
   kasan_early_init which is called by __mmap_switched(arch/arm/kernel/
   head-common.S)

2. After the calling of paging_init, we use kasan_zero_page as zero
   shadow for some memory that KASan does not need to track, and we
   allocate a new shadow space for the other memory that KASan need to
   track. These issues are finished by the function kasan_init which is
   call by setup_arch.

When using KASan we also need to increase the THREAD_SIZE_ORDER
from 1 to 2 as the extra calls for shadow memory uses quite a bit
of stack.

As we need to make a temporary copy of the PGD when setting up
shadow memory we create a helpful PGD_SIZE definition for both
LPAE and non-LPAE setups.

The KASan core code unconditionally calls pud_populate() so this
needs to be changed from BUG() to do {} while (0) when building
with KASan enabled.

After the initial development by Andre Ryabinin several modifications
have been made to this code:

Abbott Liu 
- Add support ARM LPAE: If LPAE is enabled, KASan shadow region's
  mapping table need be copied in the pgd_alloc() function.
- Change kasan_pte_populate,kasan_pmd_populate,kasan_pud_populate,
  kasan_pgd_populate from .meminit.text section to .init.text section.
  Reported by Florian Fainelli 

Linus Walleij :
- Drop the custom mainpulation of TTBR0 and just use
  cpu_switch_mm() to switch the pgd table.
- Adopt to handle 4th level page tabel folding.
- Rewrite the entire page directory and page entry initialization
  sequence to be recursive based on ARM64:s kasan_init.c.

Ard Biesheuvel :
- Necessary underlying fixes.
- Crucial bug fixes to the memory set-up code.

Co-developed-by: Andrey Ryabinin 
Co-developed-by: Abbott Liu 
Co-developed-by: Ard Biesheuvel 

Cc: Alexander Potapenko 
Cc: Dmitry Vyukov 
Cc: kasan-dev@googlegroups.com
Cc: Mike Rapoport 
Acked-by: Mike Rapoport 
Reviewed-by: Ard Biesheuvel 
Tested-by: Ard Biesheuvel  # QEMU/KVM/mach-virt/LPAE/8G
Tested-by: Florian Fainelli  # Brahma SoCs
Tested-by: Ahmad Fatoum  # i.MX6Q
Reported-by: Russell King - ARM Linux 
Reported-by: Florian Fainelli 
Signed-off-by: Andrey Ryabinin 
Signed-off-by: Abbott Liu 
Signed-off-by: Florian Fainelli 
Signed-off-by: Ard Biesheuvel 
Signed-off-by: Linus Walleij 
Signed-off-by: Russell King

ARM: 9014/2: Replace string mem* functions for KASan

2020-10-27T12:11:06+00:00

Functions like memset()/memmove()/memcpy() do a lot of memory
accesses.

If a bad pointer is passed to one of these functions it is important
to catch this. Compiler instrumentation cannot do this since these
functions are written in assembly.

KASan replaces these memory functions with instrumented variants.

The original functions are declared as weak symbols so that
the strong definitions in mm/kasan/kasan.c can replace them.

The original functions have aliases with a '__' prefix in their
name, so we can call the non-instrumented variant if needed.

We must use __memcpy()/__memset() in place of memcpy()/memset()
when we copy .data to RAM and when we clear .bss, because
kasan_early_init cannot be called before the initialization of
.data and .bss.

For the kernel compression and EFI libstub's custom string
libraries we need a special quirk: even if these are built
without KASan enabled, they rely on the global headers for their
custom string libraries, which means that e.g. memcpy()
will be defined to __memcpy() and we get link failures.
Since these implementations are written i C rather than
assembly we use e.g. __alias(memcpy) to redirected any
users back to the local implementation.

Cc: Andrey Ryabinin 
Cc: Alexander Potapenko 
Cc: Dmitry Vyukov 
Cc: kasan-dev@googlegroups.com
Reviewed-by: Ard Biesheuvel 
Tested-by: Ard Biesheuvel  # QEMU/KVM/mach-virt/LPAE/8G
Tested-by: Florian Fainelli  # Brahma SoCs
Tested-by: Ahmad Fatoum  # i.MX6Q
Reported-by: Russell King - ARM Linux 
Signed-off-by: Ahmad Fatoum 
Signed-off-by: Abbott Liu 
Signed-off-by: Florian Fainelli 
Signed-off-by: Linus Walleij 
Signed-off-by: Russell King

ARM: 8914/1: NOMMU: Fix exc_ret for XIP

2019-10-10T21:23:20+00:00

It was reported that 72cd4064fcca "NOMMU: Toggle only bits in
EXC_RETURN we are really care of" breaks NOMMU+XIP combination.
It happens because saved EXC_RETURN gets overwritten when data
section is relocated.

The fix is to propagate EXC_RETURN via register and let relocation
code to commit that value into memory.

Fixes: 72cd4064fcca ("ARM: 8830/1: NOMMU: Toggle only bits in EXC_RETURN we are really care of")
Reported-by: afzal mohammed 
Tested-by: afzal mohammed 
Signed-off-by: Vladimir Murzin 
Signed-off-by: Russell King

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

2019-06-19T15:09:55+00:00

Based on 2 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Enrico Weigelt 
Reviewed-by: Kate Stewart 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman

ARM: make lookup_processor_type() non-__init

2018-11-12T10:51:01+00:00

Move lookup_processor_type() out of the __init section so it is callable
from (eg) the secondary startup code during hotplug.

Reviewed-by: Julien Thierry 
Signed-off-by: Russell King

ARM: 8745/1: get rid of __memzero()

2018-01-21T15:37:56+00:00

The __memzero assembly code is almost identical to memset's except for
two orr instructions. The runtime performance of __memset(p, n) and
memset(p, 0, n) is accordingly almost identical.

However, the memset() macro used to guard against a zero length and to
call __memzero at compile time when the fill value is a constant zero
interferes with compiler optimizations.

Arnd found tha the test against a zero length brings up some new
warnings with gcc v8:

  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82103

And successively rremoving the test against a zero length and the call
to __memzero optimization produces the following kernel sizes for
defconfig with gcc 6:

    text     data     bss       dec       hex  filename
12248142  6278960  413588  18940690   1210312  vmlinux.orig
12244474  6278960  413588  18937022   120f4be  vmlinux.no_zero_test
12239160  6278960  413588  18931708   120dffc  vmlinux.no_memzero

So it is probably not worth keeping __memzero around given that the
compiler can do a better job at inlining trivial memset(p,0,n) on its
own. And the memset code already handles a zero length just fine.

Suggested-by: Arnd Bergmann 
Signed-off-by: Nicolas Pitre 
Acked-by: Ard Biesheuvel 
Acked-by: Arnd Bergmann 
Signed-off-by: Russell King

ARM: 8702/1: head-common.S: Clear lr before jumping to start_kernel()

2017-10-14T14:08:33+00:00

If CONFIG_DEBUG_LOCK_ALLOC=y, the kernel log is spammed with a few
hundred identical messages:

    unwind: Unknown symbol address c0800300
    unwind: Index not found c0800300

c0800300 is the return address from the last subroutine call (to
__memzero()) in __mmap_switched().  Apparently having this address in
the link register confuses the unwinder.

To fix this, reset the link register to zero before jumping to
start_kernel().

Fixes: 9520b1a1b5f7a348 ("ARM: head-common.S: speed up startup code")
Suggested-by: Ard Biesheuvel 
Signed-off-by: Geert Uytterhoeven 
Acked-by: Nicolas Pitre 
Signed-off-by: Russell King

ARM: XIP kernel: store .data compressed in ROM

2017-09-10T23:34:53+00:00

The .data segment stored in ROM is only copied to RAM once at boot time
and never referenced afterwards. This is arguably a suboptimal usage of
ROM resources.

This patch allows for compressing the .data segment before storing it
into ROM and decompressing it to RAM rather than simply copying it,
saving on precious ROM space.

Because global data is not available yet (obviously) we must allocate
decompressor workspace memory on the stack. The .bss area is used as a
stack area for that purpose before it is cleared. The required stack
frame is 9568 bytes for __inflate_kernel_data() alone, so make sure
the .bss is large enough to cope with that plus extra room for called
functions or fail the build.

Those numbers were picked arbitrarily based on the above 9568 byte
stack frame:

10240 (2.5 * PAGE_SIZE): used to override -Wframe-larger-than whose
default value is 1024.
12288 (3 * PAGE_SIZE): minimum .bss size to contain the stack.

Signed-off-by: Nicolas Pitre 
Reviewed-by: Ard Biesheuvel 
Tested-by: Chris Brandt