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.
code
Clone this repository
https://tangled.org/tjh.dev/kernel
git@gordian.tjh.dev:tjh.dev/kernel
For self-hosted knots, clone URLs may differ based on your setup.
This code requires x509_load_certificate_list() to be built-in.
Fixes: 60050ffe3d77 ("certs: Move load_certificate_list() to be with the asymmetric keys code")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Link: https://lore.kernel.org/all/202206221515.DqpUuvbQ-lkp@intel.com/
Link: https://lore.kernel.org/all/20220712104554.408dbf42@gandalf.local.home/
Signed-off-by: Adam Borowski <kilobyte@angband.pl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull perf fix from Borislav Petkov:
- Reorganize the perf LBR init code so that a TSX quirk is applied
early enough in order for the LBR MSR access to not #GP
* tag 'perf_urgent_for_v5.19_rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86/intel/lbr: Fix unchecked MSR access error on HSW
Pull scheduler fix from Borislav Petkov:
"A single fix to correct a wrong BUG_ON() condition for deboosted
tasks"
* tag 'sched_urgent_for_v5.19_rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/deadline: Fix BUG_ON condition for deboosted tasks
The fuzzer triggers the below trace.
[ 7763.384369] unchecked MSR access error: WRMSR to 0x689
(tried to write 0x1fffffff8101349e) at rIP: 0xffffffff810704a4
(native_write_msr+0x4/0x20)
[ 7763.397420] Call Trace:
[ 7763.399881] <TASK>
[ 7763.401994] intel_pmu_lbr_restore+0x9a/0x1f0
[ 7763.406363] intel_pmu_lbr_sched_task+0x91/0x1c0
[ 7763.410992] __perf_event_task_sched_in+0x1cd/0x240
On a machine with the LBR format LBR_FORMAT_EIP_FLAGS2, when the TSX is
disabled, a TSX quirk is required to access LBR from registers.
The lbr_from_signext_quirk_needed() is introduced to determine whether
the TSX quirk should be applied. However, the
lbr_from_signext_quirk_needed() is invoked before the
intel_pmu_lbr_init(), which parses the LBR format information. Without
the correct LBR format information, the TSX quirk never be applied.
Move the lbr_from_signext_quirk_needed() into the intel_pmu_lbr_init().
Checking x86_pmu.lbr_has_tsx in the lbr_from_signext_quirk_needed() is
not required anymore.
Both LBR_FORMAT_EIP_FLAGS2 and LBR_FORMAT_INFO have LBR_TSX flag, but
only the LBR_FORMAT_EIP_FLAGS2 requirs the quirk. Update the comments
accordingly.
Fixes: 1ac7fd8159a8 ("perf/x86/intel/lbr: Support LBR format V7")
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20220714182630.342107-1-kan.liang@linux.intel.com
Pull x86 fixes from Borislav Petkov:
"A couple more retbleed fallout fixes.
It looks like their urgency is decreasing so it seems like we've
managed to catch whatever snafus the limited -rc testing has exposed.
Maybe we're getting ready... :)
- Make retbleed mitigations 64-bit only (32-bit will need a bit more
work if even needed, at all).
- Prevent return thunks patching of the LKDTM modules as it is not
needed there
- Avoid writing the SPEC_CTRL MSR on every kernel entry on eIBRS
parts
- Enhance error output of apply_returns() when it fails to patch a
return thunk
- A sparse fix to the sev-guest module
- Protect EFI fw calls by issuing an IBPB on AMD"
* tag 'x86_urgent_for_v5.19_rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/speculation: Make all RETbleed mitigations 64-bit only
lkdtm: Disable return thunks in rodata.c
x86/bugs: Warn when "ibrs" mitigation is selected on Enhanced IBRS parts
x86/alternative: Report missing return thunk details
virt: sev-guest: Pass the appropriate argument type to iounmap()
x86/amd: Use IBPB for firmware calls
Tasks the are being deboosted from SCHED_DEADLINE might enter
enqueue_task_dl() one last time and hit an erroneous BUG_ON condition:
since they are not boosted anymore, the if (is_dl_boosted()) branch is
not taken, but the else if (!dl_prio) is and inside this one we
BUG_ON(!is_dl_boosted), which is of course false (BUG_ON triggered)
otherwise we had entered the if branch above. Long story short, the
current condition doesn't make sense and always leads to triggering of a
BUG.
Fix this by only checking enqueue flags, properly: ENQUEUE_REPLENISH has
to be present, but additional flags are not a problem.
Fixes: 64be6f1f5f71 ("sched/deadline: Don't replenish from a !SCHED_DEADLINE entity")
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20220714151908.533052-1-juri.lelli@redhat.com
Pull clk fix from Stephen Boyd:
"One more fix to set the correct IO mapping for a clk gate in the
lan966x driver"
* tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
clk: lan966x: Fix the lan966x clock gate register address
The mitigations for RETBleed are currently ineffective on x86_32 since
entry_32.S does not use the required macros. However, for an x86_32
target, the kconfig symbols for them are still enabled by default and
/sys/devices/system/cpu/vulnerabilities/retbleed will wrongly report
that mitigations are in place.
Make all of these symbols depend on X86_64, and only enable RETHUNK by
default on X86_64.
Fixes: f43b9876e857 ("x86/retbleed: Add fine grained Kconfig knobs")
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/YtwSR3NNsWp1ohfV@decadent.org.uk
Pull intel drm build fix from Rodrigo Vivi:
"Our 'dim' flow has a problem with fixes of fixes getting missed. We
need to take a look on that later.
Meanwhile, please allow me to quickly propagate this fix for the
32-bit build issue here upstream"
* tag 'drm-intel-fixes-2022-07-17' of git://anongit.freedesktop.org/drm/drm-intel:
drm/i915/ttm: fix 32b build
Pull kvm fixes from Paolo Bonzini:
- Check for invalid flags to KVM_CAP_X86_USER_SPACE_MSR
- Fix use of sched_setaffinity in selftests
- Sync kernel headers to tools
- Fix KVM_STATS_UNIT_MAX
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: x86: Protect the unused bits in MSR exiting flags
tools headers UAPI: Sync linux/kvm.h with the kernel sources
KVM: selftests: Fix target thread to be migrated in rseq_test
KVM: stats: Fix value for KVM_STATS_UNIT_MAX for boolean stats
The register address used for the clock gate register is the base
register address coming from first reg map (ie. the generic
clock registers) instead of the second reg map defining the clock
gate register.
Use the correct clock gate register address.
Fixes: 5ad5915dea00 ("clk: lan966x: Extend lan966x clock driver for clock gating support")
Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Link: https://lore.kernel.org/r/20220704102845.168438-2-herve.codina@bootlin.com
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Tested-by: Michael Walle <michael@walle.cc>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
The following warning was seen:
WARNING: CPU: 0 PID: 0 at arch/x86/kernel/alternative.c:557 apply_returns (arch/x86/kernel/alternative.c:557 (discriminator 1))
Modules linked in:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.19.0-rc4-00008-gee88d363d156 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-debian-1.16.0-4 04/01/2014
RIP: 0010:apply_returns (arch/x86/kernel/alternative.c:557 (discriminator 1))
Code: ff ff 74 cb 48 83 c5 04 49 39 ee 0f 87 81 fe ff ff e9 22 ff ff ff 0f 0b 48 83 c5 04 49 39 ee 0f 87 6d fe ff ff e9 0e ff ff ff <0f> 0b 48 83 c5 04 49 39 ee 0f 87 59 fe ff ff e9 fa fe ff ff 48 89
The warning happened when apply_returns() failed to convert "JMP
__x86_return_thunk" to RET. It was instead a JMP to nowhere, due to the
thunk relocation not getting resolved.
That rodata.o code is objcopy'd to .rodata, and later memcpy'd, so
relocations don't work (and are apparently silently ignored).
LKDTM is only used for testing, so the naked RET should be fine. So
just disable return thunks for that file.
While at it, disable objtool and KCSAN for the file.
Fixes: 0b53c374b9ef ("x86/retpoline: Use -mfunction-return")
Reported-by: kernel test robot <oliver.sang@intel.com>
Debugged-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/lkml/Ys58BxHxoDZ7rfpr@xsang-OptiPlex-9020/