tjh.dev
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.
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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 powerpc fixes from Michael Ellerman:
- Fix handling of PCI domains in /proc on 32-bit systems using the
recently added support for numbering buses from zero for each domain.
- A fix and a revert for some changes to use READ/WRITE_ONCE() which
caused problems with KASAN enabled due to sanitisation calls being
introduced in low-level paths that can't cope with it.
- Fix build errors on 32-bit caused by the syscall table being
misaligned sometimes.
- Two fixes to get IBM Cell native machines booting again, which had
bit-rotted while my QS22 was temporarily out of action.
- Fix the papr_scm driver to not assume the order of events returned by
the hypervisor is stable, and a related compile fix.
Thanks to Aneesh Kumar K.V, Christophe Leroy, Jordan Niethe, Kajol Jain,
Masahiro Yamada, Nathan Chancellor, Pali Rohár, Vaibhav Jain, and Zhouyi
Zhou.
* tag 'powerpc-6.0-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
powerpc/papr_scm: Ensure rc is always initialized in papr_scm_pmu_register()
Revert "powerpc/irq: Don't open code irq_soft_mask helpers"
powerpc: Fix hard_irq_disable() with sanitizer
powerpc/rtas: Fix RTAS MSR[HV] handling for Cell
Revert "powerpc: Remove unused FW_FEATURE_NATIVE references"
powerpc: align syscall table for ppc32
powerpc/pci: Enable PCI domains in /proc when PCI bus numbers are not unique
powerpc/papr_scm: Fix nvdimm event mappings
Pull kvm fixes from Paolo Bonzini:
"s390:
- PCI interpretation compile fixes
RISC-V:
- fix unused variable warnings in vcpu_timer.c
- move extern sbi_ext declarations to a header
x86:
- check validity of argument to KVM_SET_MP_STATE
- use guest's global_ctrl to completely disable guest PEBS
- fix a memory leak on memory allocation failure
- mask off unsupported and unknown bits of IA32_ARCH_CAPABILITIES
- fix build failure with Clang integrated assembler
- fix MSR interception
- always flush TLBs when enabling dirty logging"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: x86: check validity of argument to KVM_SET_MP_STATE
perf/x86/core: Completely disable guest PEBS via guest's global_ctrl
KVM: x86: fix memoryleak in kvm_arch_vcpu_create()
KVM: x86: Mask off unsupported and unknown bits of IA32_ARCH_CAPABILITIES
KVM: s390: pci: Hook to access KVM lowlevel from VFIO
riscv: kvm: move extern sbi_ext declarations to a header
riscv: kvm: vcpu_timer: fix unused variable warnings
KVM: selftests: Fix ambiguous mov in KVM_ASM_SAFE()
KVM: selftests: Fix KVM_EXCEPTION_MAGIC build with Clang
KVM: VMX: Heed the 'msr' argument in msr_write_intercepted()
kvm: x86: mmu: Always flush TLBs when enabling dirty logging
kvm: x86: mmu: Drop the need_remote_flush() function
Clang warns:
arch/powerpc/platforms/pseries/papr_scm.c:492:6: warning: variable 'rc' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
if (!p->stat_buffer_len)
^~~~~~~~~~~~~~~~~~~
arch/powerpc/platforms/pseries/papr_scm.c:523:64: note: uninitialized use occurs here
dev_info(&p->pdev->dev, "nvdimm pmu didn't register rc=%d\n", rc);
^~
include/linux/dev_printk.h:150:67: note: expanded from macro 'dev_info'
dev_printk_index_wrap(_dev_info, KERN_INFO, dev, dev_fmt(fmt), ##__VA_ARGS__)
^~~~~~~~~~~
include/linux/dev_printk.h:110:23: note: expanded from macro 'dev_printk_index_wrap'
_p_func(dev, fmt, ##__VA_ARGS__); \
^~~~~~~~~~~
arch/powerpc/platforms/pseries/papr_scm.c:492:2: note: remove the 'if' if its condition is always false
if (!p->stat_buffer_len)
^~~~~~~~~~~~~~~~~~~~~~~~
arch/powerpc/platforms/pseries/papr_scm.c:484:8: note: initialize the variable 'rc' to silence this warning
int rc, nodeid;
^
= 0
1 warning generated.
The call to papr_scm_pmu_check_events() was eliminated but a return code
was not added to the if statement. Add the same return code from
papr_scm_pmu_check_events() for this condition so there is no more
warning.
Fixes: 9b1ac04698a4 ("powerpc/papr_scm: Fix nvdimm event mappings")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://github.com/ClangBuiltLinux/linux/issues/1701
Link: https://lore.kernel.org/r/20220830151256.1473169-1-nathan@kernel.org
-Wformat was recently re-enabled for builds with clang, then quickly
re-disabled, due to concerns stemming from the frequency of default
argument promotion related warning instances.
commit 258fafcd0683 ("Makefile.extrawarn: re-enable -Wformat for clang")
commit 21f9c8a13bb2 ("Revert "Makefile.extrawarn: re-enable -Wformat for clang"")
ISO WG14 has ratified N2562 to address default argument promotion
explicitly for printf, as part of the upcoming ISO C2X standard.
The behavior of clang was changed in clang-16 to not warn for the cited
cases in all language modes.
Add a version check, so that users of clang-16 now get the full effect
of -Wformat. For older clang versions, re-enable flags under the
-Wformat group that way users still get some useful checks related to
format strings, without noisy default argument promotion warnings. I
intentionally omitted -Wformat-y2k and -Wformat-security from being
re-enabled, which are also part of -Wformat in clang-16.
Link: https://github.com/ClangBuiltLinux/linux/issues/378
Link: https://github.com/llvm/llvm-project/issues/57102
Link: https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2562.pdf
Suggested-by: Justin Stitt <jstitt007@gmail.com>
Suggested-by: Nathan Chancellor <nathan@kernel.org>
Suggested-by: Youngmin Nam <youngmin.nam@samsung.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
PCI interpretation compile fixes
This reverts commit ef5b570d3700fbb8628a58da0487486ceeb713cd.
Zhouyi reported that commit is causing crashes when running rcutorture
with KASAN enabled:
BUG: using smp_processor_id() in preemptible [00000000] code: rcu_torture_rea/100
caller is rcu_preempt_deferred_qs_irqrestore+0x74/0xed0
CPU: 4 PID: 100 Comm: rcu_torture_rea Tainted: G W 5.19.0-rc5-next-20220708-dirty #253
Call Trace:
dump_stack_lvl+0xbc/0x108 (unreliable)
check_preemption_disabled+0x154/0x160
rcu_preempt_deferred_qs_irqrestore+0x74/0xed0
__rcu_read_unlock+0x290/0x3b0
rcu_torture_read_unlock+0x30/0xb0
rcutorture_one_extend+0x198/0x810
rcu_torture_one_read+0x58c/0xc90
rcu_torture_reader+0x12c/0x360
kthread+0x1e8/0x220
ret_from_kernel_thread+0x5c/0x64
KASAN will generate instrumentation instructions around the
WRITE_ONCE(local_paca->irq_soft_mask, mask):
0xc000000000295cb0 <+0>: addis r2,r12,774
0xc000000000295cb4 <+4>: addi r2,r2,16464
0xc000000000295cb8 <+8>: mflr r0
0xc000000000295cbc <+12>: bl 0xc00000000008bb4c <mcount>
0xc000000000295cc0 <+16>: mflr r0
0xc000000000295cc4 <+20>: std r31,-8(r1)
0xc000000000295cc8 <+24>: addi r3,r13,2354
0xc000000000295ccc <+28>: mr r31,r13
0xc000000000295cd0 <+32>: std r0,16(r1)
0xc000000000295cd4 <+36>: stdu r1,-48(r1)
0xc000000000295cd8 <+40>: bl 0xc000000000609b98 <__asan_store1+8>
0xc000000000295cdc <+44>: nop
0xc000000000295ce0 <+48>: li r9,1
0xc000000000295ce4 <+52>: stb r9,2354(r31)
0xc000000000295ce8 <+56>: addi r1,r1,48
0xc000000000295cec <+60>: ld r0,16(r1)
0xc000000000295cf0 <+64>: ld r31,-8(r1)
0xc000000000295cf4 <+68>: mtlr r0
If there is a context switch before "stb r9,2354(r31)", r31 may
not equal to r13, in such case, irq soft mask will not work.
The usual solution of marking the code ineligible for instrumentation
forces the code out-of-line, which we would prefer to avoid. Christophe
proposed a partial revert, but Nick raised some concerns with that. So
for now do a full revert.
Reported-by: Zhouyi Zhou <zhouzhouyi@gmail.com>
[mpe: Construct change log based on Zhouyi's original report]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220831131052.42250-1-mpe@ellerman.id.au
Pull gpio fixes from Bartosz Golaszewski:
"A a set of fixes from the GPIO subsystem.
Most are small driver fixes except the realtek-otto driver patch which
is pretty big but addresses a significant flaw that can cause the CPU
to stay infinitely busy on uncleared ISR on some platforms.
Summary:
- MAINTAINERS update
- fix resource leaks in gpio-mockup and gpio-pxa
- add missing locking in gpio-pca953x
- use 32-bit I/O in gpio-realtek-otto
- make irq_chip structures immutable in four more drivers"
* tag 'gpio-fixes-for-v6.0-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux:
gpio: ws16c48: Make irq_chip immutable
gpio: 104-idio-16: Make irq_chip immutable
gpio: 104-idi-48: Make irq_chip immutable
gpio: 104-dio-48e: Make irq_chip immutable
gpio: realtek-otto: switch to 32-bit I/O
gpio: pca953x: Add mutex_lock for regcache sync in PM
gpio: mockup: remove gpio debugfs when remove device
gpio: pxa: use devres for the clock struct
MAINTAINERS: rectify entry for XILINX GPIO DRIVER
KVM/riscv fixes for 6.0, take #1
- Fix unused variable warnings in vcpu_timer.c
- Move extern sbi_ext declarations to a header
We have a cross dependency between KVM and VFIO when using
s390 vfio_pci_zdev extensions for PCI passthrough
To be able to keep both subsystem modular we add a registering
hook inside the S390 core code.
This fixes a build problem when VFIO is built-in and KVM is built
as a module.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Fixes: 09340b2fca007 ("KVM: s390: pci: add routines to start/stop interpretive execution")
Cc: <stable@vger.kernel.org>
Acked-by: Janosch Frank <frankja@linux.ibm.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Link: https://lore.kernel.org/r/20220819122945.9309-1-pmorel@linux.ibm.com
Message-Id: <20220819122945.9309-1-pmorel@linux.ibm.com>
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
As reported by Zhouyi Zhou, WRITE_ONCE() is not atomic
as expected when KASAN or KCSAN are compiled in.
Fix it by re-implementing it using inline assembly.
Fixes: 077fc62b2b66 ("powerpc/irq: remove inline assembly in hard_irq_disable macro")
Reported-by: Zhouyi Zhou <zhouzhouyi@gmail.com>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a8298991b3df049a54ee8e558838e34265812014.1661272586.git.christophe.leroy@csgroup.eu
Pull xen fixes from Juergen Gross:
- a minor fix for the Xen grant driver
- a small series fixing a recently introduced problem in the Xen
blkfront/blkback drivers with negotiation of feature usage
* tag 'for-linus-6.0-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
xen/grants: prevent integer overflow in gnttab_dma_alloc_pages()
xen-blkfront: Cache feature_persistent value before advertisement
xen-blkfront: Advertise feature-persistent as user requested
xen-blkback: Advertise feature-persistent as user requested
Kernel warns about mutable irq_chips:
"not an immutable chip, please consider fixing!"
Make the struct irq_chip const, flag it as IRQCHIP_IMMUTABLE, add the
new helper functions, and call the appropriate gpiolib functions.
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
An invalid argument to KVM_SET_MP_STATE has no effect other than making the
vCPU fail to run at the next KVM_RUN. Since it is extremely unlikely that
any userspace is relying on it, fail with -EINVAL just like for other
architectures.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sparse complains about missing statics in the declarations of several
variables:
arch/riscv/kvm/vcpu_sbi_replace.c:38:37: warning: symbol 'vcpu_sbi_ext_time' was not declared. Should it be static?
arch/riscv/kvm/vcpu_sbi_replace.c:73:37: warning: symbol 'vcpu_sbi_ext_ipi' was not declared. Should it be static?
arch/riscv/kvm/vcpu_sbi_replace.c:126:37: warning: symbol 'vcpu_sbi_ext_rfence' was not declared. Should it be static?
arch/riscv/kvm/vcpu_sbi_replace.c:170:37: warning: symbol 'vcpu_sbi_ext_srst' was not declared. Should it be static?
arch/riscv/kvm/vcpu_sbi_base.c:69:37: warning: symbol 'vcpu_sbi_ext_base' was not declared. Should it be static?
arch/riscv/kvm/vcpu_sbi_base.c:90:37: warning: symbol 'vcpu_sbi_ext_experimental' was not declared. Should it be static?
arch/riscv/kvm/vcpu_sbi_base.c:96:37: warning: symbol 'vcpu_sbi_ext_vendor' was not declared. Should it be static?
arch/riscv/kvm/vcpu_sbi_hsm.c:115:37: warning: symbol 'vcpu_sbi_ext_hsm' was not declared. Should it be static?
These variables are however used in vcpu_sbi.c where they are declared
as extern. Move them to kvm_vcpu_sbi.h which is handily already
included by the three other files.
Fixes: a046c2d8578c ("RISC-V: KVM: Reorganize SBI code by moving SBI v0.1 to its own file")
Fixes: 5f862df5585c ("RISC-V: KVM: Add v0.1 replacement SBI extensions defined in v0.2")
Fixes: 3e1d86569c21 ("RISC-V: KVM: Add SBI HSM extension in KVM")
Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
README