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.
Pull perf tools fixes from Arnaldo Carvalho de Melo:
- Fix compilation of callchain related code on powerpc with gcc11+
- Fix PERF_SAMPLE_WEIGHT_STRUCT support in 'perf script'
- Check session->header.env.arch before using it, fixing a segmentation
fault
- Suppress 'rm dlfilter' build messages
* tag 'perf-tools-fixes-for-v5.15-2021-10-31' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux:
perf script: Fix PERF_SAMPLE_WEIGHT_STRUCT support
perf callchain: Fix compilation on powerpc with gcc11+
perf script: Check session->header.env.arch before using it
perf build: Suppress 'rm dlfilter' build message
Pull kvm fixes from Paolo Bonzini:
- Fixes for s390 interrupt delivery
- Fixes for Xen emulator bugs showing up as debug kernel WARNs
- Fix another issue with SEV/ES string I/O VMGEXITs
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: x86: Take srcu lock in post_kvm_run_save()
KVM: SEV-ES: fix another issue with string I/O VMGEXITs
KVM: x86/xen: Fix kvm_xen_has_interrupt() sleeping in kvm_vcpu_block()
KVM: x86: switch pvclock_gtod_sync_lock to a raw spinlock
KVM: s390: preserve deliverable_mask in __airqs_kick_single_vcpu
KVM: s390: clear kicked_mask before sleeping again
-F weight in perf script is broken.
# ./perf mem record
# ./perf script -F weight
Samples for 'dummy:HG' event do not have WEIGHT attribute set. Cannot
print 'weight' field.
The sample type, PERF_SAMPLE_WEIGHT_STRUCT, is an alternative of the
PERF_SAMPLE_WEIGHT sample type. They share the same space, weight. The
lower 32 bits are exactly the same for both sample type. The higher 32
bits may be different for different architecture. For a new kernel on
x86, the PERF_SAMPLE_WEIGHT_STRUCT is used. For an old kernel or other
ARCHs, the PERF_SAMPLE_WEIGHT is used.
With -F weight, current perf script will only check the input string
"weight" with the PERF_SAMPLE_WEIGHT sample type. Because the commit
ea8d0ed6eae3 ("perf tools: Support PERF_SAMPLE_WEIGHT_STRUCT") didn't
update the PERF_SAMPLE_WEIGHT_STRUCT sample type for perf script. For a
new kernel on x86, the check fails.
Use PERF_SAMPLE_WEIGHT_TYPE, which supports both sample types, to
replace PERF_SAMPLE_WEIGHT
Fixes: ea8d0ed6eae37b01 ("perf tools: Support PERF_SAMPLE_WEIGHT_STRUCT")
Reported-by: Joe Mario <jmario@redhat.com>
Reviewed-by: Kajol Jain <kjain@linux.ibm.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Tested-by: Jiri Olsa <jolsa@redhat.com>
Tested-by: Joe Mario <jmario@redhat.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Joe Mario <jmario@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Link: https://lore.kernel.org/r/1632929894-102778-1-git-send-email-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Pull SCSI fixes from James Bottomley:
"Three small fixes, all in drivers, and one sizeable update to the UFS
driver to remove the HPB 2.0 feature that has been objected to by Jens
and Christoph.
Although the UFS patch is large and last minute, it's essentially the
least intrusive way of resolving the objections in time for the 5.15
release"
* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
scsi: ufs: ufshpb: Remove HPB2.0 flows
scsi: mpt3sas: Fix reference tag handling for WRITE_INSERT
scsi: ufs: ufs-exynos: Correct timeout value setting registers
scsi: ibmvfc: Fix up duplicate response detection
The Xen interrupt injection for event channels relies on accessing the
guest's vcpu_info structure in __kvm_xen_has_interrupt(), through a
gfn_to_hva_cache.
This requires the srcu lock to be held, which is mostly the case except
for this code path:
[ 11.822877] WARNING: suspicious RCU usage
[ 11.822965] -----------------------------
[ 11.823013] include/linux/kvm_host.h:664 suspicious rcu_dereference_check() usage!
[ 11.823131]
[ 11.823131] other info that might help us debug this:
[ 11.823131]
[ 11.823196]
[ 11.823196] rcu_scheduler_active = 2, debug_locks = 1
[ 11.823253] 1 lock held by dom:0/90:
[ 11.823292] #0: ffff998956ec8118 (&vcpu->mutex){+.+.}, at: kvm_vcpu_ioctl+0x85/0x680
[ 11.823379]
[ 11.823379] stack backtrace:
[ 11.823428] CPU: 2 PID: 90 Comm: dom:0 Kdump: loaded Not tainted 5.4.34+ #5
[ 11.823496] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
[ 11.823612] Call Trace:
[ 11.823645] dump_stack+0x7a/0xa5
[ 11.823681] lockdep_rcu_suspicious+0xc5/0x100
[ 11.823726] __kvm_xen_has_interrupt+0x179/0x190
[ 11.823773] kvm_cpu_has_extint+0x6d/0x90
[ 11.823813] kvm_cpu_accept_dm_intr+0xd/0x40
[ 11.823853] kvm_vcpu_ready_for_interrupt_injection+0x20/0x30
< post_kvm_run_save() inlined here >
[ 11.823906] kvm_arch_vcpu_ioctl_run+0x135/0x6a0
[ 11.823947] kvm_vcpu_ioctl+0x263/0x680
Fixes: 40da8ccd724f ("KVM: x86/xen: Add event channel interrupt vector upcall")
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Cc: stable@vger.kernel.org
Message-Id: <606aaaf29fca3850a63aa4499826104e77a72346.camel@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Got following build fail on powerpc:
CC arch/powerpc/util/skip-callchain-idx.o
In function ‘check_return_reg’,
inlined from ‘check_return_addr’ at arch/powerpc/util/skip-callchain-idx.c:213:7,
inlined from ‘arch_skip_callchain_idx’ at arch/powerpc/util/skip-callchain-idx.c:265:7:
arch/powerpc/util/skip-callchain-idx.c:54:18: error: ‘dwarf_frame_register’ accessing 96 bytes \
in a region of size 64 [-Werror=stringop-overflow=]
54 | result = dwarf_frame_register(frame, ra_regno, ops_mem, &ops, &nops);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
arch/powerpc/util/skip-callchain-idx.c: In function ‘arch_skip_callchain_idx’:
arch/powerpc/util/skip-callchain-idx.c:54:18: note: referencing argument 3 of type ‘Dwarf_Op *’
In file included from /usr/include/elfutils/libdwfl.h:32,
from arch/powerpc/util/skip-callchain-idx.c:10:
/usr/include/elfutils/libdw.h:1069:12: note: in a call to function ‘dwarf_frame_register’
1069 | extern int dwarf_frame_register (Dwarf_Frame *frame, int regno,
| ^~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
The dwarf_frame_register args changed with [1],
Updating ops_mem accordingly.
[1] https://sourceware.org/git/?p=elfutils.git;a=commit;h=5621fe5443da23112170235dd5cac161e5c75e65
Reviewed-by: Kajol Jain <kjain@linux.ibm.com>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Mark Wieelard <mjw@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Link: https://lore.kernel.org/r/20210928195253.1267023-1-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Pull clk fix from Stephen Boyd:
"One fix for the composite clk that broke when we changed this clk type
to use the determine_rate instead of round_rate clk op by default.
This caused lots of problems on Rockchip SoCs because they heavily use
the composite clk code to model the clk tree"
* tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
clk: composite: Also consider .determine_rate for rate + mux composites
The Host Performance Buffer feature allows UFS read commands to carry the
physical media addresses along with the LBAs, thus allowing less internal
L2P-table switches in the device. HPB1.0 allowed a single LBA, while
HPB2.0 increases this capacity up to 255 blocks.
Carrying more than a single record, the read operation is no longer purely
of type "read" but a "hybrid" command: Writing the physical address to the
device in one operation and reading back the required payload in another.
The JEDEC HPB spec defines two commands for this operation:
HPB-WRITE-BUFFER (0x2) to write the physical addresses to device, and
HPB-READ to read the payload.
With the current HPB design the UFS driver has no alternative but to divide
the READ request into 2 separate commands: HPB-WRITE-BUFFER and HPB-READ.
This causes a great deal of aggravation to the block layer guys who
demanded that we completely revert the entire HPB driver regardless of the
huge amount of corporate effort already invested in it.
As a compromise, remove only the pieces that implement the 2.0
specification. This is done as a matter of urgency for the final 5.15
release.
Link: https://lore.kernel.org/r/20211030062301.248-1-avri.altman@wdc.com
Tested-by: Avri Altman <avri.altman@wdc.com>
Tested-by: Bean Huo <beanhuo@micron.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Bean Huo <beanhuo@micron.com>
Co-developed-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Avri Altman <avri.altman@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
If the guest requests string I/O from the hypervisor via VMGEXIT,
SW_EXITINFO2 will contain the REP count. However, sev_es_string_io
was incorrectly treating it as the size of the GHCB buffer in
bytes.
This fixes the "outsw" test in the experimental SEV tests of
kvm-unit-tests.
Cc: stable@vger.kernel.org
Fixes: 7ed9abfe8e9f ("KVM: SVM: Support string IO operations for an SEV-ES guest")
Reported-by: Marc Orr <marcorr@google.com>
Tested-by: Marc Orr <marcorr@google.com>
Reviewed-by: Marc Orr <marcorr@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When perf.data is not written cleanly, we would like to process existing
data as much as possible (please see f_header.data.size == 0 condition
in perf_session__read_header). However, perf.data with partial data may
crash perf. Specifically, we see crash in 'perf script' for NULL
session->header.env.arch.
Fix this by checking session->header.env.arch before using it to determine
native_arch. Also split the if condition so it is easier to read.
Committer notes:
If it is a pipe, we already assume is a native arch, so no need to check
session->header.env.arch.
Signed-off-by: Song Liu <songliubraving@fb.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: kernel-team@fb.com
Cc: stable@vger.kernel.org
Link: http://lore.kernel.org/lkml/20211004053238.514936-1-songliubraving@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Pull RISC-V fixes from Palmer Dabbelt:
"These are pretty late, but they do fix concrete issues.
- ensure the trap vector's address is aligned.
- avoid re-populating the KASAN shadow memory.
- allow kasan to build without warnings, which have recently become
errors"
* tag 'riscv-for-linus-5.15-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
riscv: Fix asan-stack clang build
riscv: Do not re-populate shadow memory with kasan_populate_early_shadow
riscv: fix misalgned trap vector base address
Commit 69a00fb3d69706 ("clk: divider: Implement and wire up
.determine_rate by default") switches clk_divider_ops to implement
.determine_rate by default. This breaks composite clocks with multiple
parents because clk-composite.c does not use the special handling for
mux + divider combinations anymore (that was restricted to rate clocks
which only implement .round_rate, but not .determine_rate).
Alex reports:
This breaks lot of clocks for Rockchip which intensively uses
composites, i.e. those clocks will always stay at the initial parent,
which in some cases is the XTAL clock and I strongly guess it is the
same for other platforms, which use composite clocks having more than
one parent (e.g. mediatek, ti ...)
Example (RK3399)
clk_sdio is set (initialized) with XTAL (24 MHz) as parent in u-boot.
It will always stay at this parent, even if the mmc driver sets a rate
of 200 MHz (fails, as the nature of things), which should switch it
to any of its possible parent PLLs defined in
mux_pll_src_cpll_gpll_npll_ppll_upll_24m_p (see clk-rk3399.c) - which
never happens.
Restore the original behavior by changing the priority of the conditions
inside clk-composite.c. Now the special rate + mux case (with rate_ops
having a .round_rate - which is still the case for the default
clk_divider_ops) is preferred over rate_ops which have .determine_rate
defined (and not further considering the mux).
Fixes: 69a00fb3d69706 ("clk: divider: Implement and wire up .determine_rate by default")
Reported-by: Alex Bee <knaerzche@gmail.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://lore.kernel.org/r/20211016105022.303413-2-martin.blumenstingl@googlemail.com
Tested-by: Alex Bee <knaerzche@gmail.com>
Tested-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Testing revealed a problem with how the reference tag was handled for
a WRITE_INSERT operation. The SCSI_PROT_REF_CHECK flag is not set when
the controller is asked to generate the protection information
(i.e. not DIX). And as a result the initial reference tag would not be
set in the WRITE_INSERT case.
Separate handling of the REF_CHECK and REF_INCREMENT flags to align
with both the DIX spec and the MPI implementation.
Link: https://lore.kernel.org/r/20211028034202.24225-1-martin.petersen@oracle.com
Fixes: b3e2c72af1d5 ("scsi: mpt3sas: Use the proper SCSI midlayer interfaces for PI")
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>