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Filename Latest commit message Latest commit date
Josh Poimboeuf c2102ac103 x86/mm: Fix RESERVE_BRK() for older binutils
commit e32683c6f7d22ba624e0bfc58b02cf3348bdca63 upstream.

With binutils 2.26, RESERVE_BRK() causes a build failure:

  /tmp/ccnGOKZ5.s: Assembler messages:
  /tmp/ccnGOKZ5.s:98: Error: missing ')'
  /tmp/ccnGOKZ5.s:98: Error: missing ')'
  /tmp/ccnGOKZ5.s:98: Error: missing ')'
  /tmp/ccnGOKZ5.s:98: Error: junk at end of line, first unrecognized
  character is `U'

The problem is this line:

  RESERVE_BRK(early_pgt_alloc, INIT_PGT_BUF_SIZE)

Specifically, the INIT_PGT_BUF_SIZE macro which (via PAGE_SIZE's use
_AC()) has a "1UL", which makes older versions of the assembler unhappy.
Unfortunately the _AC() macro doesn't work for inline asm.

Inline asm was only needed here to convince the toolchain to add the
STT_NOBITS flag.  However, if a C variable is placed in a section whose
name is prefixed with ".bss", GCC and Clang automatically set
STT_NOBITS.  In fact, ".bss..page_aligned" already relies on this trick.

So fix the build failure (and simplify the macro) by allocating the
variable in C.

Also, add NOLOAD to the ".brk" output section clause in the linker
script.  This is a failsafe in case the ".bss" prefix magic trick ever
stops working somehow.  If there's a section type mismatch, the GNU
linker will force the ".brk" output section to be STT_NOBITS.  The LLVM
linker will fail with a "section type mismatch" error.

Note this also changes the name of the variable from .brk.##name to
__brk_##name.  The variable names aren't actually used anywhere, so it's
harmless.

Fixes: a1e2c031ec39 ("x86/mm: Simplify RESERVE_BRK()")
Reported-by: Joe Damato <jdamato@fastly.com>
Reported-by: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Joe Damato <jdamato@fastly.com>
Link: https://lore.kernel.org/r/22d07a44c80d8e8e1e82b9a806ddc8c6bbb2606e.1654759036.git.jpoimboe@kernel.org
[nathan: Fix conflict due to lack of 360db4ace311 and resolve silent
         conflict with 360db4ace3117]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-11-08 11:23:39 +01:00
arch x86/mm: Fix RESERVE_BRK() for older binutils 2023-11-08 11:23:39 +01:00
block
certs
crypto
Documentation
drivers drm/dp_mst: Fix NULL deref in get_mst_branch_device_by_guid_helper() 2023-11-08 11:23:38 +01:00
fs nfsd: lock_rename() needs both directories to live on the same fs 2023-11-08 11:23:38 +01:00
include gtp: uapi: fix GTPA_MAX 2023-11-08 11:23:36 +01:00
init
ipc
kernel perf/core: Fix potential NULL deref 2023-11-08 11:23:37 +01:00
lib kobject: Fix slab-out-of-bounds in fill_kobj_path() 2023-11-08 11:23:38 +01:00
LICENSES
mm
net tcp: fix wrong RTO timeout when received SACK reneging 2023-11-08 11:23:36 +01:00
samples
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tools selftests/ftrace: Add new test case which checks non unique symbol 2023-11-08 11:23:34 +01:00
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Linux kernel
============

There are several guides for kernel developers and users. These guides can
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Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.