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ea73179e64
Michael reported that we are seeing an ftrace bug on bootup when KASAN
is enabled and we are using -fpatchable-function-entry:
ftrace: allocating 47780 entries in 18 pages
ftrace-powerpc: 0xc0000000020b3d5c: No module provided for non-kernel address
------------[ ftrace bug ]------------
ftrace faulted on modifying
[<c0000000020b3d5c>] 0xc0000000020b3d5c
Initializing ftrace call sites
ftrace record flags: 0
(0)
expected tramp: c00000000008cef4
------------[ cut here ]------------
WARNING: CPU: 0 PID: 0 at kernel/trace/ftrace.c:2180 ftrace_bug+0x3c0/0x424
Modules linked in:
CPU: 0 PID: 0 Comm: swapper Not tainted 6.5.0-rc3-00120-g0f71dcfb4aef #860
Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1202 0xf000005 of:SLOF,HEAD hv:linux,kvm pSeries
NIP: c0000000003aa81c LR: c0000000003aa818 CTR: 0000000000000000
REGS: c0000000033cfab0 TRAP: 0700 Not tainted (6.5.0-rc3-00120-g0f71dcfb4aef)
MSR: 8000000002021033 <SF,VEC,ME,IR,DR,RI,LE> CR: 28028240 XER: 00000000
CFAR: c0000000002781a8 IRQMASK: 3
...
NIP [c0000000003aa81c] ftrace_bug+0x3c0/0x424
LR [c0000000003aa818] ftrace_bug+0x3bc/0x424
Call Trace:
ftrace_bug+0x3bc/0x424 (unreliable)
ftrace_process_locs+0x5f4/0x8a0
ftrace_init+0xc0/0x1d0
start_kernel+0x1d8/0x484
With CONFIG_FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY=y and
CONFIG_KASAN=y, compiler emits nops in functions that it generates for
registering and unregistering global variables (unlike with -pg and
-mprofile-kernel where calls to _mcount() are not generated in those
functions). Those functions then end up in INIT_TEXT and EXIT_TEXT
respectively. We don't expect to see any profiled functions in
EXIT_TEXT, so ftrace_init_nop() assumes that all addresses that aren't
in the core kernel text belongs to a module. Since these functions do
not match that criteria, we see the above bug.
Address this by having ftrace ignore all locations in the text exit
sections of vmlinux.
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
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.