Merge more updates from Andrew Morton:
"More mm/ work, plenty more to come
Subsystems affected by this patch series: slub, memcg, gup, kasan,
pagealloc, hugetlb, vmscan, tools, mempolicy, memblock, hugetlbfs,
thp, mmap, kconfig"
* akpm: (131 commits)
arm64: mm: use ARCH_HAS_DEBUG_WX instead of arch defined
x86: mm: use ARCH_HAS_DEBUG_WX instead of arch defined
riscv: support DEBUG_WX
mm: add DEBUG_WX support
drivers/base/memory.c: cache memory blocks in xarray to accelerate lookup
mm/thp: rename pmd_mknotpresent() as pmd_mkinvalid()
powerpc/mm: drop platform defined pmd_mknotpresent()
mm: thp: don't need to drain lru cache when splitting and mlocking THP
hugetlbfs: get unmapped area below TASK_UNMAPPED_BASE for hugetlbfs
sparc32: register memory occupied by kernel as memblock.memory
include/linux/memblock.h: fix minor typo and unclear comment
mm, mempolicy: fix up gup usage in lookup_node
tools/vm/page_owner_sort.c: filter out unneeded line
mm: swap: memcg: fix memcg stats for huge pages
mm: swap: fix vmstats for huge pages
mm: vmscan: limit the range of LRU type balancing
mm: vmscan: reclaim writepage is IO cost
mm: vmscan: determine anon/file pressure balance at the reclaim root
mm: balance LRU lists based on relative thrashing
mm: only count actual rotations as LRU reclaim cost
...
Without swap page tracking, users that are otherwise memory controlled can
easily escape their containment and allocate significant amounts of memory
that they're not being charged for. That's because swap does readahead,
but without the cgroup records of who owned the page at swapout, readahead
pages don't get charged until somebody actually faults them into their
page table and we can identify an owner task. This can be maliciously
exploited with MADV_WILLNEED, which triggers arbitrary readahead
allocations without charging the pages.
Make swap swap page tracking an integral part of memcg and remove the
Kconfig options. In the first place, it was only made configurable to
allow users to save some memory. But the overhead of tracking cgroup
ownership per swap page is minimal - 2 byte per page, or 512k per 1G of
swap, or 0.04%. Saving that at the expense of broken containment
semantics is not something we should present as a coequal option.
The swapaccount=0 boot option will continue to exist, and it will
eliminate the page_counter overhead and hide the swap control files, but
it won't disable swap slot ownership tracking.
This patch makes sure we always have the cgroup records at swapin time;
the next patch will fix the actual bug by charging readahead swap pages at
swapin time rather than at fault time.
v2: fix double swap charge bug in cgroup1/cgroup2 code gating
[hannes@cmpxchg.org: fix crash with cgroup_disable=memory]
Link: http://lkml.kernel.org/r/20200521215855.GB815153@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Naresh Kamboju <naresh.kamboju@linaro.org>
Link: http://lkml.kernel.org/r/20200508183105.225460-16-hannes@cmpxchg.org
Debugged-by: Hugh Dickins <hughd@google.com>
Debugged-by: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull MIPS updates from Thomas Bogendoerfer:
- added support for MIPSr5 and P5600 cores
- converted Loongson PCI driver into a PCI host driver using the
generic PCI framework
- added emulation of CPUCFG command for Loogonson64 cpus
- removed of LASAT, PMC MSP71xx and NEC MARKEINS/EMMA
- ioremap cleanup
- fix for a race between two threads faulting the same page
- various cleanups and fixes
* tag 'mips_5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux: (143 commits)
MIPS: ralink: drop ralink_clk_init for mt7621
MIPS: ralink: bootrom: mark a function as __init to save some memory
MIPS: Loongson64: Reorder CPUCFG model match arms
MIPS: Expose Loongson CPUCFG availability via HWCAP
MIPS: Loongson64: Guard against future cores without CPUCFG
MIPS: Fix build warning about "PTR_STR" redefinition
MIPS: Loongson64: Remove not used pci.c
MIPS: Loongson64: Define PCI_IOBASE
MIPS: CPU_LOONGSON2EF need software to maintain cache consistency
MIPS: DTS: Fix build errors used with various configs
MIPS: Loongson64: select NO_EXCEPT_FILL
MIPS: Fix IRQ tracing when call handle_fpe() and handle_msa_fpe()
MIPS: mm: add page valid judgement in function pte_modify
mm/memory.c: Add memory read privilege on page fault handling
mm/memory.c: Update local TLB if PTE entry exists
MIPS: Do not flush tlb page when updating PTE entry
MIPS: ingenic: Default to a generic board
MIPS: ingenic: Add support for GCW Zero prototype
MIPS: ingenic: DTS: Add memory info of GCW Zero
MIPS: Loongson64: Switch to generic PCI driver
...
Pull arm64 updates from Will Deacon:
"A sizeable pile of arm64 updates for 5.8.
Summary below, but the big two features are support for Branch Target
Identification and Clang's Shadow Call stack. The latter is currently
arm64-only, but the high-level parts are all in core code so it could
easily be adopted by other architectures pending toolchain support
Branch Target Identification (BTI):
- Support for ARMv8.5-BTI in both user- and kernel-space. This allows
branch targets to limit the types of branch from which they can be
called and additionally prevents branching to arbitrary code,
although kernel support requires a very recent toolchain.
- Function annotation via SYM_FUNC_START() so that assembly functions
are wrapped with the relevant "landing pad" instructions.
- BPF and vDSO updates to use the new instructions.
- Addition of a new HWCAP and exposure of BTI capability to userspace
via ID register emulation, along with ELF loader support for the
BTI feature in .note.gnu.property.
- Non-critical fixes to CFI unwind annotations in the sigreturn
trampoline.
Shadow Call Stack (SCS):
- Support for Clang's Shadow Call Stack feature, which reserves
platform register x18 to point at a separate stack for each task
that holds only return addresses. This protects function return
control flow from buffer overruns on the main stack.
- Save/restore of x18 across problematic boundaries (user-mode,
hypervisor, EFI, suspend, etc).
- Core support for SCS, should other architectures want to use it
too.
- SCS overflow checking on context-switch as part of the existing
stack limit check if CONFIG_SCHED_STACK_END_CHECK=y.
CPU feature detection:
- Removed numerous "SANITY CHECK" errors when running on a system
with mismatched AArch32 support at EL1. This is primarily a concern
for KVM, which disabled support for 32-bit guests on such a system.
- Addition of new ID registers and fields as the architecture has
been extended.
Perf and PMU drivers:
- Minor fixes and cleanups to system PMU drivers.
Hardware errata:
- Unify KVM workarounds for VHE and nVHE configurations.
- Sort vendor errata entries in Kconfig.
Secure Monitor Call Calling Convention (SMCCC):
- Update to the latest specification from Arm (v1.2).
- Allow PSCI code to query the SMCCC version.
Software Delegated Exception Interface (SDEI):
- Unexport a bunch of unused symbols.
- Minor fixes to handling of firmware data.
Pointer authentication:
- Add support for dumping the kernel PAC mask in vmcoreinfo so that
the stack can be unwound by tools such as kdump.
- Simplification of key initialisation during CPU bringup.
BPF backend:
- Improve immediate generation for logical and add/sub instructions.
vDSO:
- Minor fixes to the linker flags for consistency with other
architectures and support for LLVM's unwinder.
- Clean up logic to initialise and map the vDSO into userspace.
ACPI:
- Work around for an ambiguity in the IORT specification relating to
the "num_ids" field.
- Support _DMA method for all named components rather than only PCIe
root complexes.
- Minor other IORT-related fixes.
Miscellaneous:
- Initialise debug traps early for KGDB and fix KDB cacheflushing
deadlock.
- Minor tweaks to early boot state (documentation update, set
TEXT_OFFSET to 0x0, increase alignment of PE/COFF sections).
- Refactoring and cleanup"
* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (148 commits)
KVM: arm64: Move __load_guest_stage2 to kvm_mmu.h
KVM: arm64: Check advertised Stage-2 page size capability
arm64/cpufeature: Add get_arm64_ftr_reg_nowarn()
ACPI/IORT: Remove the unused __get_pci_rid()
arm64/cpuinfo: Add ID_MMFR4_EL1 into the cpuinfo_arm64 context
arm64/cpufeature: Add remaining feature bits in ID_AA64PFR1 register
arm64/cpufeature: Add remaining feature bits in ID_AA64PFR0 register
arm64/cpufeature: Add remaining feature bits in ID_AA64ISAR0 register
arm64/cpufeature: Add remaining feature bits in ID_MMFR4 register
arm64/cpufeature: Add remaining feature bits in ID_PFR0 register
arm64/cpufeature: Introduce ID_MMFR5 CPU register
arm64/cpufeature: Introduce ID_DFR1 CPU register
arm64/cpufeature: Introduce ID_PFR2 CPU register
arm64/cpufeature: Make doublelock a signed feature in ID_AA64DFR0
arm64/cpufeature: Drop TraceFilt feature exposure from ID_DFR0 register
arm64/cpufeature: Add explicit ftr_id_isar0[] for ID_ISAR0 register
arm64: mm: Add asid_gen_match() helper
firmware: smccc: Fix missing prototype warning for arm_smccc_version_init
arm64: vdso: Fix CFI directives in sigreturn trampoline
arm64: vdso: Don't prefix sigreturn trampoline with a BTI C instruction
...
Pull x86 boot updates from Ingo Molnar:
"Misc updates:
- Add the initrdmem= boot option to specify an initrd embedded in RAM
(flash most likely)
- Sanitize the CS value earlier during boot, which also fixes SEV-ES
- Various fixes and smaller cleanups"
* tag 'x86-boot-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/boot: Correct relocation destination on old linkers
x86/boot/compressed/64: Switch to __KERNEL_CS after GDT is loaded
x86/boot: Fix -Wint-to-pointer-cast build warning
x86/boot: Add kstrtoul() from lib/
x86/tboot: Mark tboot static
x86/setup: Add an initrdmem= option to specify initrd physical address
Pull RCU updates from Ingo Molnar:
"The RCU updates for this cycle were:
- RCU-tasks update, including addition of RCU Tasks Trace for BPF use
and TASKS_RUDE_RCU
- kfree_rcu() updates.
- Remove scheduler locking restriction
- RCU CPU stall warning updates.
- Torture-test updates.
- Miscellaneous fixes and other updates"
* tag 'core-rcu-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (103 commits)
rcu: Allow for smp_call_function() running callbacks from idle
rcu: Provide rcu_irq_exit_check_preempt()
rcu: Abstract out rcu_irq_enter_check_tick() from rcu_nmi_enter()
rcu: Provide __rcu_is_watching()
rcu: Provide rcu_irq_exit_preempt()
rcu: Make RCU IRQ enter/exit functions rely on in_nmi()
rcu/tree: Mark the idle relevant functions noinstr
x86: Replace ist_enter() with nmi_enter()
x86/mce: Send #MC singal from task work
x86/entry: Get rid of ist_begin/end_non_atomic()
sched,rcu,tracing: Avoid tracing before in_nmi() is correct
sh/ftrace: Move arch_ftrace_nmi_{enter,exit} into nmi exception
lockdep: Always inline lockdep_{off,on}()
hardirq/nmi: Allow nested nmi_enter()
arm64: Prepare arch_nmi_enter() for recursion
printk: Disallow instrumenting print_nmi_enter()
printk: Prepare for nested printk_nmi_enter()
rcutorture: Convert ULONG_CMP_LT() to time_before()
torture: Add a --kasan argument
torture: Save a few lines by using config_override_param initially
...
Pull x86 fix from Borislav Petkov:
"A single fix for early boot crashes of kernels built with gcc10 and
stack protector enabled"
* tag 'x86_urgent_for_v5.7-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86: Fix early boot crash on gcc-10, third try
Pull networking fixes from David Miller:
1) Fix sk_psock reference count leak on receive, from Xiyu Yang.
2) CONFIG_HNS should be invisible, from Geert Uytterhoeven.
3) Don't allow locking route MTUs in ipv6, RFCs actually forbid this,
from Maciej Żenczykowski.
4) ipv4 route redirect backoff wasn't actually enforced, from Paolo
Abeni.
5) Fix netprio cgroup v2 leak, from Zefan Li.
6) Fix infinite loop on rmmod in conntrack, from Florian Westphal.
7) Fix tcp SO_RCVLOWAT hangs, from Eric Dumazet.
8) Various bpf probe handling fixes, from Daniel Borkmann.
* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (68 commits)
selftests: mptcp: pm: rm the right tmp file
dpaa2-eth: properly handle buffer size restrictions
bpf: Restrict bpf_trace_printk()'s %s usage and add %pks, %pus specifier
bpf: Add bpf_probe_read_{user, kernel}_str() to do_refine_retval_range
bpf: Restrict bpf_probe_read{, str}() only to archs where they work
MAINTAINERS: Mark networking drivers as Maintained.
ipmr: Add lockdep expression to ipmr_for_each_table macro
ipmr: Fix RCU list debugging warning
drivers: net: hamradio: Fix suspicious RCU usage warning in bpqether.c
net: phy: broadcom: fix BCM54XX_SHD_SCR3_TRDDAPD value for BCM54810
tcp: fix error recovery in tcp_zerocopy_receive()
MAINTAINERS: Add Jakub to networking drivers.
MAINTAINERS: another add of Karsten Graul for S390 networking
drivers: ipa: fix typos for ipa_smp2p structure doc
pppoe: only process PADT targeted at local interfaces
selftests/bpf: Enforce returning 0 for fentry/fexit programs
bpf: Enforce returning 0 for fentry/fexit progs
net: stmmac: fix num_por initialization
security: Fix the default value of secid_to_secctx hook
libbpf: Fix register naming in PT_REGS s390 macros
...
This change adds generic support for Clang's Shadow Call Stack,
which uses a shadow stack to protect return addresses from being
overwritten by an attacker. Details are available here:
https://clang.llvm.org/docs/ShadowCallStack.html
Note that security guarantees in the kernel differ from the ones
documented for user space. The kernel must store addresses of
shadow stacks in memory, which means an attacker capable reading
and writing arbitrary memory may be able to locate them and hijack
control flow by modifying the stacks.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
[will: Numerous cosmetic changes]
Signed-off-by: Will Deacon <will@kernel.org>
Given the legacy bpf_probe_read{,str}() BPF helpers are broken on archs
with overlapping address ranges, we should really take the next step to
disable them from BPF use there.
To generally fix the situation, we've recently added new helper variants
bpf_probe_read_{user,kernel}() and bpf_probe_read_{user,kernel}_str().
For details on them, see 6ae08ae3de ("bpf: Add probe_read_{user, kernel}
and probe_read_{user,kernel}_str helpers").
Given bpf_probe_read{,str}() have been around for ~5 years by now, there
are plenty of users at least on x86 still relying on them today, so we
cannot remove them entirely w/o breaking the BPF tracing ecosystem.
However, their use should be restricted to archs with non-overlapping
address ranges where they are working in their current form. Therefore,
move this behind a CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE and
have x86, arm64, arm select it (other archs supporting it can follow-up
on it as well).
For the remaining archs, they can workaround easily by relying on the
feature probe from bpftool which spills out defines that can be used out
of BPF C code to implement the drop-in replacement for old/new kernels
via: bpftool feature probe macro
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/bpf/20200515101118.6508-2-daniel@iogearbox.net
... or the odyssey of trying to disable the stack protector for the
function which generates the stack canary value.
The whole story started with Sergei reporting a boot crash with a kernel
built with gcc-10:
Kernel panic — not syncing: stack-protector: Kernel stack is corrupted in: start_secondary
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.6.0-rc5—00235—gfffb08b37df9 #139
Hardware name: Gigabyte Technology Co., Ltd. To be filled by O.E.M./H77M—D3H, BIOS F12 11/14/2013
Call Trace:
dump_stack
panic
? start_secondary
__stack_chk_fail
start_secondary
secondary_startup_64
-—-[ end Kernel panic — not syncing: stack—protector: Kernel stack is corrupted in: start_secondary
This happens because gcc-10 tail-call optimizes the last function call
in start_secondary() - cpu_startup_entry() - and thus emits a stack
canary check which fails because the canary value changes after the
boot_init_stack_canary() call.
To fix that, the initial attempt was to mark the one function which
generates the stack canary with:
__attribute__((optimize("-fno-stack-protector"))) ... start_secondary(void *unused)
however, using the optimize attribute doesn't work cumulatively
as the attribute does not add to but rather replaces previously
supplied optimization options - roughly all -fxxx options.
The key one among them being -fno-omit-frame-pointer and thus leading to
not present frame pointer - frame pointer which the kernel needs.
The next attempt to prevent compilers from tail-call optimizing
the last function call cpu_startup_entry(), shy of carving out
start_secondary() into a separate compilation unit and building it with
-fno-stack-protector, was to add an empty asm("").
This current solution was short and sweet, and reportedly, is supported
by both compilers but we didn't get very far this time: future (LTO?)
optimization passes could potentially eliminate this, which leads us
to the third attempt: having an actual memory barrier there which the
compiler cannot ignore or move around etc.
That should hold for a long time, but hey we said that about the other
two solutions too so...
Reported-by: Sergei Trofimovich <slyfox@gentoo.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Kalle Valo <kvalo@codeaurora.org>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200314164451.346497-1-slyfox@gentoo.org
Pull tracing fixes from Steven Rostedt:
"Fixes to previous fixes.
Unfortunately, the last set of fixes introduced some minor bugs:
- The bootconfig apply_xbc() leak fix caused the application to
return a positive number on success, when it should have returned
zero.
- The preempt_irq_delay_thread fix to make the creation code wait for
the kthread to finish to prevent it from executing after module
unload, can now cause the kthread to exit before it even executes
(preventing it to run its tests).
- The fix to the bootconfig that fixed the initrd to remove the
bootconfig from causing the kernel to panic, now prints a warning
that the bootconfig is not found, even when bootconfig is not on
the command line"
* tag 'trace-v5.7-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
bootconfig: Fix to prevent warning message if no bootconfig option
tracing: Wait for preempt irq delay thread to execute
tools/bootconfig: Fix apply_xbc() to return zero on success
Similarly to the CC_IS_CLANG config, add LD_IS_LLD to avoid GNU ld
specific logic such as ld-version or ld-ifversion and gain the
ability to select potential features that depend on the linker at
configuration time such as LTO.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Masahiro Yamada <masahiroy@kernel.org>
[nc: Reword commit message]
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
It seems that for whatever reason, gcc-10 ends up not inlining a couple
of functions that used to be inlined before. Even if they only have one
single callsite - it looks like gcc may have decided that the code was
unlikely, and not worth inlining.
The code generation difference is harmless, but caused a few new section
mismatch errors, since the (now no longer inlined) function wasn't in
the __init section, but called other init functions:
Section mismatch in reference from the function kexec_free_initrd() to the function .init.text:free_initrd_mem()
Section mismatch in reference from the function tpm2_calc_event_log_size() to the function .init.text:early_memremap()
Section mismatch in reference from the function tpm2_calc_event_log_size() to the function .init.text:early_memunmap()
So add the appropriate __init annotation to make modpost not complain.
In both cases there were trivially just a single callsite from another
__init function.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We have some rather random rules about when we accept the
"maybe-initialized" warnings, and when we don't.
For example, we consider it unreliable for gcc versions < 4.9, but also
if -O3 is enabled, or if optimizing for size. And then various kernel
config options disabled it, because they know that they trigger that
warning by confusing gcc sufficiently (ie PROFILE_ALL_BRANCHES).
And now gcc-10 seems to be introducing a lot of those warnings too, so
it falls under the same heading as 4.9 did.
At the same time, we have a very straightforward way to _enable_ that
warning when wanted: use "W=2" to enable more warnings.
So stop playing these ad-hoc games, and just disable that warning by
default, with the known and straight-forward "if you want to work on the
extra compiler warnings, use W=123".
Would it be great to have code that is always so obvious that it never
confuses the compiler whether a variable is used initialized or not?
Yes, it would. In a perfect world, the compilers would be smarter, and
our source code would be simpler.
That's currently not the world we live in, though.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If there is a bootconfig data in the tail of initrd/initramfs,
initrd image sanity check caused an error while decompression
stage as follows.
[ 0.883882] Unpacking initramfs...
[ 2.696429] Initramfs unpacking failed: invalid magic at start of compressed archive
This error will be ignored if CONFIG_BLK_DEV_RAM=n,
but CONFIG_BLK_DEV_RAM=y the kernel failed to mount rootfs
and causes a panic.
To fix this issue, shrink down the initrd_end for removing
tailing bootconfig data while boot the kernel.
Link: http://lkml.kernel.org/r/158788401014.24243.17424755854115077915.stgit@devnote2
Cc: Borislav Petkov <bp@alien8.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@vger.kernel.org
Fixes: 7684b8582c ("bootconfig: Load boot config from the tail of initrd")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit splits ->trc_reader_need_end by using the rcu_special union.
This change permits readers to check to see if a memory barrier is
required without any added overhead in the common case where no such
barrier is required. This commit also adds the read-side checking.
Later commits will add the machinery to properly set the new
->trc_reader_special.b.need_mb field.
This commit also makes rcu_read_unlock_trace_special() tolerate nested
read-side critical sections within interrupt and NMI handlers.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Because RCU does not watch exception early-entry/late-exit, idle-loop,
or CPU-hotplug execution, protection of tracing and BPF operations is
needlessly complicated. This commit therefore adds a variant of
Tasks RCU that:
o Has explicit read-side markers to allow finite grace periods in
the face of in-kernel loops for PREEMPT=n builds. These markers
are rcu_read_lock_trace() and rcu_read_unlock_trace().
o Protects code in the idle loop, exception entry/exit, and
CPU-hotplug code paths. In this respect, RCU-tasks trace is
similar to SRCU, but with lighter-weight readers.
o Avoids expensive read-side instruction, having overhead similar
to that of Preemptible RCU.
There are of course downsides:
o The grace-period code can send IPIs to CPUs, even when those
CPUs are in the idle loop or in nohz_full userspace. This is
mitigated by later commits.
o It is necessary to scan the full tasklist, much as for Tasks RCU.
o There is a single callback queue guarded by a single lock,
again, much as for Tasks RCU. However, those early use cases
that request multiple grace periods in quick succession are
expected to do so from a single task, which makes the single
lock almost irrelevant. If needed, multiple callback queues
can be provided using any number of schemes.
Perhaps most important, this variant of RCU does not affect the vanilla
flavors, rcu_preempt and rcu_sched. The fact that RCU Tasks Trace
readers can operate from idle, offline, and exception entry/exit in no
way enables rcu_preempt and rcu_sched readers to do so.
The memory ordering was outlined here:
https://lore.kernel.org/lkml/20200319034030.GX3199@paulmck-ThinkPad-P72/
This effort benefited greatly from off-list discussions of BPF
requirements with Alexei Starovoitov and Andrii Nakryiko. At least
some of the on-list discussions are captured in the Link: tags below.
In addition, KCSAN was quite helpful in finding some early bugs.
Link: https://lore.kernel.org/lkml/20200219150744.428764577@infradead.org/
Link: https://lore.kernel.org/lkml/87mu8p797b.fsf@nanos.tec.linutronix.de/
Link: https://lore.kernel.org/lkml/20200225221305.605144982@linutronix.de/
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andrii Nakryiko <andriin@fb.com>
[ paulmck: Apply feedback from Steve Rostedt and Joel Fernandes. ]
[ paulmck: Decrement trc_n_readers_need_end upon IPI failure. ]
[ paulmck: Fix locking issue reported by rcutorture. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Add the initrdmem option:
initrdmem=ss[KMG],nn[KMG]
which is used to specify the physical address of the initrd, almost
always an address in FLASH. Also add code for x86 to use the existing
phys_init_start and phys_init_size variables in the kernel.
This is useful in cases where a kernel and an initrd is placed in FLASH,
but there is no firmware file system structure in the FLASH.
One such situation occurs when unused FLASH space on UEFI systems has
been reclaimed by, e.g., taking it from the Management Engine. For
example, on many systems, the ME is given half the FLASH part; not only
is 2.75M of an 8M part unused; but 10.75M of a 16M part is unused. This
space can be used to contain an initrd, but need to tell Linux where it
is.
This space is "raw": due to, e.g., UEFI limitations: it can not be added
to UEFI firmware volumes without rebuilding UEFI from source or writing
a UEFI device driver. It can be referenced only as a physical address
and size.
At the same time, if a kernel can be "netbooted" or loaded from GRUB or
syslinux, the option of not using the physical address specification
should be available.
Then, it is easy to boot the kernel and provide an initrd; or boot the
the kernel and let it use the initrd in FLASH. In practice, this has
proven to be very helpful when integrating Linux into FLASH on x86.
Hence, the most flexible and convenient path is to enable the initrdmem
command line option in a way that it is the last choice tried.
For example, on the DigitalLoggers Atomic Pi, an image into FLASH can be
burnt in with a built-in command line which includes:
initrdmem=0xff968000,0x200000
which specifies a location and size.
[ bp: Massage commit message, make it passive. ]
[akpm@linux-foundation.org: coding style fixes]
Signed-off-by: Ronald G. Minnich <rminnich@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Link: http://lkml.kernel.org/r/CAP6exYLK11rhreX=6QPyDQmW7wPHsKNEFtXE47pjx41xS6O7-A@mail.gmail.com
Link: https://lkml.kernel.org/r/20200426011021.1cskg0AGd%akpm@linux-foundation.org
Pull more Kbuild updates from Masahiro Yamada:
- raise minimum supported binutils version to 2.23
- remove old CONFIG_AS_* macros that we know binutils >= 2.23 supports
- move remaining CONFIG_AS_* tests to Kconfig from Makefile
- enable -Wtautological-compare warnings to catch more issues
- do not support GCC plugins for GCC <= 4.7
- fix various breakages of 'make xconfig'
- include the linker version used for linking the kernel into
LINUX_COMPILER, which is used for the banner, and also exposed to
/proc/version
- link lib-y objects to vmlinux forcibly when CONFIG_MODULES=y, which
allows us to remove the lib-ksyms.o workaround, and to solve the last
known issue of the LLVM linker
- add dummy tools in scripts/dummy-tools/ to enable all compiler tests
in Kconfig, which will be useful for distro maintainers
- support the single switch, LLVM=1 to use Clang and all LLVM utilities
instead of GCC and Binutils.
- support LLVM_IAS=1 to enable the integrated assembler, which is still
experimental
* tag 'kbuild-v5.7-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (36 commits)
kbuild: fix comment about missing include guard detection
kbuild: support LLVM=1 to switch the default tools to Clang/LLVM
kbuild: replace AS=clang with LLVM_IAS=1
kbuild: add dummy toolchains to enable all cc-option etc. in Kconfig
kbuild: link lib-y objects to vmlinux forcibly when CONFIG_MODULES=y
MIPS: fw: arc: add __weak to prom_meminit and prom_free_prom_memory
kbuild: remove -I$(srctree)/tools/include from scripts/Makefile
kbuild: do not pass $(KBUILD_CFLAGS) to scripts/mkcompile_h
Documentation/llvm: fix the name of llvm-size
kbuild: mkcompile_h: Include $LD version in /proc/version
kconfig: qconf: Fix a few alignment issues
kconfig: qconf: remove some old bogus TODOs
kconfig: qconf: fix support for the split view mode
kconfig: qconf: fix the content of the main widget
kconfig: qconf: Change title for the item window
kconfig: qconf: clean deprecated warnings
gcc-plugins: drop support for GCC <= 4.7
kbuild: Enable -Wtautological-compare
x86: update AS_* macros to binutils >=2.23, supporting ADX and AVX2
crypto: x86 - clean up poly1305-x86_64-cryptogams.S by 'make clean'
...
printk_deferred(), similarly to printk_safe/printk_nmi, does not
immediately attempt to print a new message on the consoles, avoiding
calls into non-reentrant kernel paths, e.g. scheduler or timekeeping,
which potentially can deadlock the system.
Those printk() flavors, instead, rely on per-CPU flush irq_work to print
messages from safer contexts. For same reasons (recursive scheduler or
timekeeping calls) printk() uses per-CPU irq_work in order to wake up
user space syslog/kmsg readers.
However, only printk_safe/printk_nmi do make sure that per-CPU areas
have been initialised and that it's safe to modify per-CPU irq_work.
This means that, for instance, should printk_deferred() be invoked "too
early", that is before per-CPU areas are initialised, printk_deferred()
will perform illegal per-CPU access.
Lech Perczak [0] reports that after commit 1b710b1b10 ("char/random:
silence a lockdep splat with printk()") user-space syslog/kmsg readers
are not able to read new kernel messages.
The reason is printk_deferred() being called too early (as was pointed
out by Petr and John).
Fix printk_deferred() and do not queue per-CPU irq_work before per-CPU
areas are initialized.
Link: https://lore.kernel.org/lkml/aa0732c6-5c4e-8a8b-a1c1-75ebe3dca05b@camlintechnologies.com/
Reported-by: Lech Perczak <l.perczak@camlintechnologies.com>
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Tested-by: Jann Horn <jannh@google.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull arm64 fixes from Catalin Marinas:
- Ensure that the compiler and linker versions are aligned so that ld
doesn't complain about not understanding a .note.gnu.property section
(emitted when pointer authentication is enabled).
- Force -mbranch-protection=none when the feature is not enabled, in
case a compiler may choose a different default value.
- Remove CONFIG_DEBUG_ALIGN_RODATA. It was never in defconfig and
rarely enabled.
- Fix checking 16-bit Thumb-2 instructions checking mask in the
emulation of the SETEND instruction (it could match the bottom half
of a 32-bit Thumb-2 instruction).
* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
arm64: armv8_deprecated: Fix undef_hook mask for thumb setend
arm64: remove CONFIG_DEBUG_ALIGN_RODATA feature
arm64: Always force a branch protection mode when the compiler has one
arm64: Kconfig: ptrauth: Add binutils version check to fix mismatch
init/kconfig: Add LD_VERSION Kconfig
Linus Torvalds
Johannes Weiner
Daniel Jordan
Thomas Gleixner
Sami Tolvanen
Daniel Borkmann
Borislav Petkov
Masami Hiramatsu
Paul E. McKenney
Ronald G. Minnich
Sergey Senozhatsky