rtas_os_term() is called during panic. Its behavior depends on a couple
of conditions in the /rtas node of the device tree, the traversal of
which entails locking and local IRQ state changes. If the kernel panics
while devtree_lock is held, rtas_os_term() as currently written could
hang.
Instead of discovering the relevant characteristics at panic time,
cache them in file-static variables at boot. Note the lookup for
"ibm,extended-os-term" is converted to of_property_read_bool() since it
is a boolean property, not an RTAS function token.
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>
[mpe: Incorporate suggested change from Nick]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221118150751.469393-4-nathanl@linux.ibm.com
rtas_token() should be used only for properties that are RTAS function
tokens. "rtas-event-scan-rate" does not contain a function token, but it
has the same size/format as token properties so reading it with
rtas_token() happens to work.
Convert to of_property_read_u32().
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221118150751.469393-3-nathanl@linux.ibm.com
rtas_call() has a complex calling convention, non-standard return
values, and many users. Add kernel-doc for it and remove the less
structured commentary from rtas.h.
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221118150751.469393-2-nathanl@linux.ibm.com
At boot time, the FDT is parsed to compute the number of CPUs.
In addition count the number of CPU nodes and export it.
This is useful when building the FDT for a kexeced kernel since we need to
take in account the CPU node added since the boot time during CPU hotplug
operations.
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221110180619.15796-2-ldufour@linux.ibm.com
Zero GPRS r14-r31 on entry into the kernel for interrupt sources to
limit influence of user-space values in potential speculation gadgets.
Prior to this commit, all other GPRS are reassigned during the common
prologue to interrupt handlers and so need not be zeroised explicitly.
This may be done safely, without loss of register state prior to the
interrupt, as the common prologue saves the initial values of
non-volatiles, which are unconditionally restored in interrupt_64.S.
Mitigation defaults to enabled by INTERRUPT_SANITIZE_REGISTERS.
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221201071019.1953023-6-rmclure@linux.ibm.com
Zeroise user state in gprs (assign to zero) to reduce the influence of user
registers on speculation within kernel syscall handlers. Clears occur
at the very beginning of the sc and scv 0 interrupt handlers, with
restores occurring following the execution of the syscall handler.
Zeroise GPRS r0, r2-r11, r14-r31, on entry into the kernel for all
other interrupt sources. The remaining gprs are overwritten by
entry macros to interrupt handlers, irrespective of whether or not a
given handler consumes these register values. If an interrupt does not
select the IMSR_R12 IOption, zeroise r12.
Prior to this commit, r14-r31 are restored on a per-interrupt basis at
exit, but now they are always restored on 64bit Book3S. Remove explicit
REST_NVGPRS invocations on 64-bit Book3S. 32-bit systems do not clear
user registers on interrupt, and continue to depend on the return value
of interrupt_exit_user_prepare to determine whether or not to restore
non-volatiles.
The mmap_bench benchmark in selftests should rapidly invoke pagefaults.
See ~0.8% performance regression with this mitigation, but this
indicates the worst-case performance due to heavier-weight interrupt
handlers. This mitigation is able to be enabled/disabled through
CONFIG_INTERRUPT_SANITIZE_REGISTERS.
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221201071019.1953023-5-rmclure@linux.ibm.com
Interrupt handlers in asm/exceptions-64s.S contain a great deal of common
code produced by the GEN_COMMON macros. Currently, at the exit point of
the macro, r12 will contain the contents of the MSR. A future patch will
cause these macros to zeroise architected registers to avoid potential
speculation influence of user data.
Provide an IOption that signals that r12 must be retained, as the
interrupt handler assumes it to hold the contents of the MSR.
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221201071019.1953023-4-rmclure@linux.ibm.com
Interrupt code is shared between Book3E/S 64-bit systems for interrupt
handlers. Ensure that exit code correctly restores non-volatile gprs on
each system when CONFIG_INTERRUPT_SANITIZE_REGISTERS is enabled.
Also introduce macros for clearing/restoring registers on interrupt
entry for when this configuration option is either disabled or enabled.
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221201071019.1953023-3-rmclure@linux.ibm.com
This affects only 64-bit ELFv2 kernels, and reduces the minimum
asm-created stack frame size from 112 to 32 byte on those kernels.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221127124942.1665522-16-npiggin@gmail.com
Most callers just want to validate an arbitrary kernel stack pointer,
some need a particular size. Make the size case the exceptional one
with an extra function.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221127124942.1665522-15-npiggin@gmail.com
Stack unwinders need LR and the back chain as a minimum. The switch
stack uses regs->nip for its return pointer rather than lrsave, so
that was not set in the fork frame, and neither was the back chain.
This change sets those fields in the stack.
With this and the previous change, a stack trace in the switch or
interrupt stack goes from looking like this:
Oops: Exception in kernel mode, sig: 5 [#1]
LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA pSeries
Modules linked in:
CPU: 3 PID: 90 Comm: systemd Not tainted
NIP: c000000000011060 LR: c000000000010f68 CTR: 0000000000007fff
[ ... regs ... ]
NIP [c000000000011060] _switch+0x160/0x17c
LR [c000000000010f68] _switch+0x68/0x17c
Call Trace:
To this:
Oops: Exception in kernel mode, sig: 5 [#1]
LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA pSeries
CPU: 0 PID: 93 Comm: systemd Not tainted
NIP: c000000000011060 LR: c000000000010f68 CTR: 0000000000007fff
[ ... regs ... ]
NIP [c000000000011060] _switch+0x160/0x17c
LR [c000000000010f68] _switch+0x68/0x17c
Call Trace:
[c000000005a93e10] [c00000000000cdbc] ret_from_fork_scv+0x0/0x54
--- interrupt: 3000 at 0x7fffa72f56d8
NIP: 00007fffa72f56d8 LR: 0000000000000000 CTR: 0000000000000000
[ ... regs ... ]
NIP [00007fffa72f56d8] 0x7fffa72f56d8
LR [0000000000000000] 0x0
--- interrupt: 3000
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221127124942.1665522-14-npiggin@gmail.com
Backtraces will not recognise the fork system call interrupt without
the regs marker. And regular interrupt entry from userspace creates
the back chain to the user stack, so do this for the initial fork
frame too, to be consistent.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221127124942.1665522-13-npiggin@gmail.com
This is open-coded in process.c, ppc32 uses a different define with the
same value, and the C definition is name differently which makes it an
extra indirection to grep for.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221127124942.1665522-12-npiggin@gmail.com
This is a count of longs from the stack pointer to the regs marker.
Rename it to make it more distinct from the other byte offsets. It
can be derived from the byte offset definitions just added.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221127124942.1665522-10-npiggin@gmail.com
This is a common offset that currently uses the overloaded
STACK_FRAME_OVERHEAD constant. It's easier to read and more
flexible to use a specific regs offset for this.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221127124942.1665522-8-npiggin@gmail.com
This makes it a bit clearer where the stack frame is created, and will
allow easier use of some of the stack offset constants in a later
change.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221127124942.1665522-5-npiggin@gmail.com
Override the generic module ELF check to provide a check for the ELF ABI
version. This becomes important if we allow big-endian ELF ABI V2 builds
but it doesn't hurt to check now.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221128041539.1742489-3-npiggin@gmail.com
find_timens_vvar_page() is not architecture-specific, as can be seen from
how all five per-architecture versions of it are the same.
(arm64, powerpc and riscv are exactly the same; x86 and s390 have two
characters difference inside a comment, less blank lines, and mark the
!CONFIG_TIME_NS version as inline.)
Refactor the five copies into a central copy in kernel/time/namespace.c.
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20221130115320.2918447-1-jannh@google.com
For the coming temporary mm used for instruction patching, the
breakpoint registers need to be cleared to prevent them from
accidentally being triggered. As soon as the patching is done, the
breakpoints will be restored.
The breakpoint state is stored in the per-cpu variable current_brk[].
Add a suspend_breakpoints() function which will clear the breakpoint
registers without touching the state in current_brk[]. Add a pair
function restore_breakpoints() which will move the state in
current_brk[] back to the registers.
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221109045112.187069-2-bgray@linux.ibm.com
In hw_breakpoint_handler(), ea is set by wp_get_instr_detail() except
for 8xx, leading the variable to be passed uninitialised to
wp_check_constraints(). This is safe as wp_check_constraints() returns
early without using ea, so just set it to make the compiler happy.
Signed-off-by: Russell Currey <ruscur@russell.cc>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221024041346.103608-1-ruscur@russell.cc
preempt_enable_no_resched() is just the same as preempt_enable() when we
are in a irqs disabled context. kprobe_handler() and the post/fault
handlers are all called with irqs disabled. As such, convert those to
just use preempt_enable().
Reported-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/72639f75fe66f931ec8c2165276ffbfb0fe1006f.1666262278.git.naveen.n.rao@linux.vnet.ibm.com
Similar to x86 commit 2e62024c26 ("kprobes/x86: Use preempt_enable()
in optimized_callback()"), change powerpc optprobes to use
preempt_enable() rather than preempt_enable_no_resched() since powerpc
also removed irq disabling for optprobes in commit f72180cc93
("powerpc/kprobes: Do not disable interrupts for optprobes and
kprobes_on_ftrace").
Reported-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1885bab182626c33d9bf6421f430abf924c521a5.1666262278.git.naveen.n.rao@linux.vnet.ibm.com
arch_prepare_kprobe() is called from register_kprobe() via
prepare_kprobe(), or through register_aggr_kprobe(), both with the
kprobe_mutex held. Per the comment for get_kprobe():
/*
* This routine is called either:
* - under the 'kprobe_mutex' - during kprobe_[un]register().
* OR
* - with preemption disabled - from architecture specific code.
*/
As such, there is no need to disable preemption around the call to
get_kprobe(). Drop the same.
Reported-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1043d06a0affed83a4a46dd29466e72820ee215d.1666262278.git.naveen.n.rao@linux.vnet.ibm.com
cputime_t was a core kernel type, removed by commits
ed5c8c854f2b..b672592f0221. As explained in commit b672592f02
("sched/cputime: Remove generic asm headers"), the final cleanup
is for the arch to provide cputime_to_nsec[s](). Commit ade7667a98
("powerpc: Add cputime_to_nsecs()") did that, but justdidn't remove
the then-unused cputime_to_usecs(), cputime_t type, and associated
remnants.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221006105653.115829-1-npiggin@gmail.com
Although the previous commit made the powerpc instruction dump usable
with scripts/decodecode, there are still some problems.
Because the dump is split across multiple lines, the script doesn't cope
with printk timestamps or caller info.
That can be fixed by printing the entire dump on one line, eg:
[ 12.016307][ T112] --- interrupt: c00
[ 12.016605][ T112] Code: 4b7aae15 60000000 3d22016e 3c62ffec 39291160 38639bc0 e8890000 4b7aadf9 60000000 4bfffee8 7c0802a6 60000000 <0fe00000> 60420000 3c4c008f 384268a0
[ 12.017655][ T112] ---[ end trace 0000000000000000 ]---
That output can then be piped directly into scripts/decodecode and
interpreted correctly.
Printing the dump on a single line does produce a very long line, about
173 characters. That is still shorter than x86, which prints nearly 200
characters even without timestamps etc.
All consoles I'm aware of will wrap the line if it's too long, so the
length should not be a functional problem. If anything it should help on
consoles like VGA by using less vertical space.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221006032019.1128624-2-mpe@ellerman.id.au
Matt reported that scripts/decodecode doesn't work for the instruction
dump in the powerpc oops output. Although there are scripts around that
can decode it, it would be preferable if the standard in-tree script
worked.
All other arches prefix the instruction dump with "Code:", and that's
what the script looks for, so use that.
The script then works as expected:
$ CROSS_COMPILE=powerpc64le-linux-gnu- ./scripts/decodecode
Code:
fbc1fff0 f821ffc1 7c7d1b78 7c9c2378 ebc30028 7fdff378 48000018 60000000
60000000 ebff0008 7c3ef840 41820048 <815f0060> e93f0000 5529077c 7d295378
^D
All code
========
0: f0 ff c1 fb std r30,-16(r1)
4: c1 ff 21 f8 stdu r1,-64(r1)
8: 78 1b 7d 7c mr r29,r3
...
Note that the script doesn't cope well with printk timestamps or printk
caller info.
Reported-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221006032019.1128624-1-mpe@ellerman.id.au
The kvm code was refactored to convert some of kvm assembly routines to C.
This includes commits which moved code path for the kvm guest entry/exit
for p7/8 from aseembly to C. As part of the code changes, usage of some of
the macros were removed. But definitions still exist in the assembly files.
Commits are listed below:
Commit 2e1ae9cd56 ("KVM: PPC: Book3S HV: Implement radix prefetch workaround by disabling MMU")
Commit 9769a7fd79 ("KVM: PPC: Book3S HV: Remove radix guest support from P7/8 path")
Commit fae5c9f366 ("KVM: PPC: Book3S HV: remove ISA v3.0 and v3.1 support from P7/8 path")
Commit 57dc0eed73 ("KVM: PPC: Book3S HV P9: Implement PMU save/restore in C")
Many of the asm-offset macro definitions were missed to remove. Patch
fixes by removing the unused macros.
Signed-off-by: Disha Goel <disgoel@linux.vnet.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220916105736.268153-2-disgoel@linux.vnet.ibm.com
Do not run objtool on VDSO files, by using OBJECT_FILES_NON_STANDARD.
Suggested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221114175754.1131267-8-sv@linux.ibm.com
Fix several annotations in assembly files on PPC32.
[Sathvika Vasireddy: Changed subject line and removed Kconfig change to
enable objtool, as it is a part of "objtool/powerpc: Enable objtool to
be built on ppc" patch in this series.]
Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221114175754.1131267-7-sv@linux.ibm.com
This is a simple mechanical transformation done by:
@@
expression E;
@@
- prandom_u32_max
+ get_random_u32_below
(E)
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Darrick J. Wong <djwong@kernel.org> # for xfs
Reviewed-by: SeongJae Park <sj@kernel.org> # for damon
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> # for infiniband
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> # for arm
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # for mmc
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
.data.rel.ro* catches .data.rel.root_cpuacct, and the kernel crashes on
a store in css_clear_dir. At least we know read-only data protection is
working...
Fixes: b6adc6d6d3 ("powerpc/build: move .data.rel.ro, .sdata2 to read-only")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221116043954.3307852-1-npiggin@gmail.com
With the introduction of syscall wrappers all wrappers for syscalls with
64-bit arguments must be handled specially, not only those that have
unaligned 64-bit arguments. This left out the fallocate() and
sync_file_range2() syscalls.
Fixes: 7e92e01b72 ("powerpc: Provide syscall wrapper")
Fixes: e237506238 ("powerpc/32: fix syscall wrappers with 64-bit arguments of unaligned register-pairs")
Signed-off-by: Andreas Schwab <schwab@linux-m68k.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/87mt9cxd6g.fsf_-_@igel.home
Commit a4cb3651a1 ("powerpc/64s/interrupt: Fix lost interrupts when
returning to soft-masked context") fixed the problem of pending irqs
being cleared when clearing the HARD_DIS bit, but then it didn't clear
the bit at all. This change clears HARD_DIS without affecting other bits
in the mask.
When an interrupt hits in a soft-masked section that has MSR[EE]=1, it
can hard disable and set PACA_IRQS_HARD_DIS, which must be cleared when
returning to the EE=1 caller (unless it was set due to a MUST_HARD_MASK
interrupt becoming pending). Failure to clear this leaves the
returned-to context running with MSR[EE]=1 and PACA_IRQS_HARD_DIS, which
confuses irq assertions and could be dangerous for code that might test
the flag.
This was observed in a hash MMU kernel where a kernel hash fault hits in
a local_irqs_disabled region that has EE=1. The hash fault also runs
with EE=1, then as it returns, a decrementer hits in the restart section
and the irq restart code hard-masks which sets the PACA_IRQ_HARD_DIS
flag, which is not clear when the original context is returned to.
Reported-by: Sachin Sant <sachinp@linux.ibm.com>
Fixes: a4cb3651a1 ("powerpc/64s/interrupt: Fix lost interrupts when returning to soft-masked context")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Tested-by: Sachin Sant <sachinp@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221022052207.471328-1-npiggin@gmail.com
NMI interrupts should exit with EXCEPTION_RESTORE_REGS not with
interrupt_return_srr, which is what the perf NMI handler currently does.
This breaks if a PMI hits after interrupt_exit_user_prepare_main() has
switched the context tracking to user mode, then the CT_WARN_ON() in
interrupt_exit_kernel_prepare() fires because it returns to kernel with
context set to user.
This could possibly be solved by soft-disabling PMIs in the exit path,
but that reduces our ability to profile that code. The warning could be
removed, but it's potentially useful.
All other NMIs and soft-NMIs return using EXCEPTION_RESTORE_REGS, so
this makes perf interrupts consistent with that and seems like the best
fix.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Squash in fixups from Nick]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221006140413.126443-3-npiggin@gmail.com
NMI PMIs really should not return using the normal interrupt_return
function. If such a PMI hits in code returning to user with the context
switched to user mode, this warning can fire. This was enough to cause
crashes when reproducing on 64s, because another perf interrupt would
hit while reporting bug, and that would cause another bug, and so on
until smashing the stack.
Work around that particular crash for now by just disabling that context
warning for PMIs. This is a hack and not a complete fix, there could be
other such problems lurking in corners. But it does fix the known crash.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221014030729.2077151-3-npiggin@gmail.com
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Merge tag 'random-6.1-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random
Pull more random number generator updates from Jason Donenfeld:
"This time with some large scale treewide cleanups.
The intent of this pull is to clean up the way callers fetch random
integers. The current rules for doing this right are:
- If you want a secure or an insecure random u64, use get_random_u64()
- If you want a secure or an insecure random u32, use get_random_u32()
The old function prandom_u32() has been deprecated for a while
now and is just a wrapper around get_random_u32(). Same for
get_random_int().
- If you want a secure or an insecure random u16, use get_random_u16()
- If you want a secure or an insecure random u8, use get_random_u8()
- If you want secure or insecure random bytes, use get_random_bytes().
The old function prandom_bytes() has been deprecated for a while
now and has long been a wrapper around get_random_bytes()
- If you want a non-uniform random u32, u16, or u8 bounded by a
certain open interval maximum, use prandom_u32_max()
I say "non-uniform", because it doesn't do any rejection sampling
or divisions. Hence, it stays within the prandom_*() namespace, not
the get_random_*() namespace.
I'm currently investigating a "uniform" function for 6.2. We'll see
what comes of that.
By applying these rules uniformly, we get several benefits:
- By using prandom_u32_max() with an upper-bound that the compiler
can prove at compile-time is ≤65536 or ≤256, internally
get_random_u16() or get_random_u8() is used, which wastes fewer
batched random bytes, and hence has higher throughput.
- By using prandom_u32_max() instead of %, when the upper-bound is
not a constant, division is still avoided, because
prandom_u32_max() uses a faster multiplication-based trick instead.
- By using get_random_u16() or get_random_u8() in cases where the
return value is intended to indeed be a u16 or a u8, we waste fewer
batched random bytes, and hence have higher throughput.
This series was originally done by hand while I was on an airplane
without Internet. Later, Kees and I worked on retroactively figuring
out what could be done with Coccinelle and what had to be done
manually, and then we split things up based on that.
So while this touches a lot of files, the actual amount of code that's
hand fiddled is comfortably small"
* tag 'random-6.1-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random:
prandom: remove unused functions
treewide: use get_random_bytes() when possible
treewide: use get_random_u32() when possible
treewide: use get_random_{u8,u16}() when possible, part 2
treewide: use get_random_{u8,u16}() when possible, part 1
treewide: use prandom_u32_max() when possible, part 2
treewide: use prandom_u32_max() when possible, part 1
- Fix 32-bit syscall wrappers with 64-bit arguments of unaligned register-pairs.
Notably this broke ftruncate64 & pread/write64, which can lead to file corruption.
- Fix lost interrupts when returning to soft-masked context on 64-bit.
- Fix build failure when CONFIG_DTL=n.
Thanks to: Nicholas Piggin, Jason A. Donenfeld, Guenter Roeck, Arnd Bergmann, Sachin Sant.
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Merge tag 'powerpc-6.1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc fixes from Michael Ellerman:
- Fix 32-bit syscall wrappers with 64-bit arguments of unaligned
register-pairs. Notably this broke ftruncate64 & pread/write64, which
can lead to file corruption.
- Fix lost interrupts when returning to soft-masked context on 64-bit.
- Fix build failure when CONFIG_DTL=n.
Thanks to Nicholas Piggin, Jason A. Donenfeld, Guenter Roeck, Arnd
Bergmann, and Sachin Sant.
* tag 'powerpc-6.1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
powerpc/pseries: Fix CONFIG_DTL=n build
powerpc/64s/interrupt: Fix lost interrupts when returning to soft-masked context
powerpc/32: fix syscall wrappers with 64-bit arguments of unaligned register-pairs
It's possible for an interrupt returning to an irqs-disabled context to
lose a pending soft-masked irq because it branches to part of the exit
code for irqs-enabled contexts, which is meant to clear only the
PACA_IRQS_HARD_DIS flag from PACAIRQHAPPENED by zeroing the byte. This
just looks like a simple thinko from a recent commit (if there was no
hard mask pending, there would be no reason to clear it anyway).
This also adds comment to the code that actually does need to clear the
flag.
Fixes: e485f6c751 ("powerpc/64/interrupt: Fix return to masked context after hard-mask irq becomes pending")
Reported-by: Sachin Sant <sachinp@linux.ibm.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221013064418.1311104-1-npiggin@gmail.com
- Valentin Schneider makes crash-kexec work properly when invoked from
an NMI-time panic.
- ntfs bugfixes from Hawkins Jiawei
- Jiebin Sun improves IPC msg scalability by replacing atomic_t's with
percpu counters.
- nilfs2 cleanups from Minghao Chi
- lots of other single patches all over the tree!
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Merge tag 'mm-nonmm-stable-2022-10-11' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull non-MM updates from Andrew Morton:
- hfs and hfsplus kmap API modernization (Fabio Francesco)
- make crash-kexec work properly when invoked from an NMI-time panic
(Valentin Schneider)
- ntfs bugfixes (Hawkins Jiawei)
- improve IPC msg scalability by replacing atomic_t's with percpu
counters (Jiebin Sun)
- nilfs2 cleanups (Minghao Chi)
- lots of other single patches all over the tree!
* tag 'mm-nonmm-stable-2022-10-11' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (71 commits)
include/linux/entry-common.h: remove has_signal comment of arch_do_signal_or_restart() prototype
proc: test how it holds up with mapping'less process
mailmap: update Frank Rowand email address
ia64: mca: use strscpy() is more robust and safer
init/Kconfig: fix unmet direct dependencies
ia64: update config files
nilfs2: replace WARN_ONs by nilfs_error for checkpoint acquisition failure
fork: remove duplicate included header files
init/main.c: remove unnecessary (void*) conversions
proc: mark more files as permanent
nilfs2: remove the unneeded result variable
nilfs2: delete unnecessary checks before brelse()
checkpatch: warn for non-standard fixes tag style
usr/gen_init_cpio.c: remove unnecessary -1 values from int file
ipc/msg: mitigate the lock contention with percpu counter
percpu: add percpu_counter_add_local and percpu_counter_sub_local
fs/ocfs2: fix repeated words in comments
relay: use kvcalloc to alloc page array in relay_alloc_page_array
proc: make config PROC_CHILDREN depend on PROC_FS
fs: uninline inode_maybe_inc_iversion()
...
powerpc 32-bit system call (and function) calling convention for 64-bit
arguments requires the next available odd-pair (two sequential registers
with the first being odd-numbered) from the standard register argument
allocation.
The first argument register is r3, so a 64-bit argument that appears at
an even position in the argument list must skip a register (unless there
were preceding 64-bit arguments, which might throw things off). This
requires non-standard compat definitions to deal with the holes in the
argument register allocation.
With pt_regs syscall wrappers which use a standard mapper to map pt_regs
GPRs to function arguments, 32-bit kernels hit the same basic problem,
the standard definitions don't cope with the unused argument registers.
Fix this by having 32-bit kernels share those syscall definitions with
compat.
Thanks to Jason for spending a lot of time finding and bisecting this
and developing a trivial reproducer. The perfect bug report.
Reported-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Fixes: 7e92e01b72 ("powerpc: Provide syscall wrapper")
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221012035335.866440-1-npiggin@gmail.com
Rather than incurring a division or requesting too many random bytes for
the given range, use the prandom_u32_max() function, which only takes
the minimum required bytes from the RNG and avoids divisions. This was
done mechanically with this coccinelle script:
@basic@
expression E;
type T;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
typedef u64;
@@
(
- ((T)get_random_u32() % (E))
+ prandom_u32_max(E)
|
- ((T)get_random_u32() & ((E) - 1))
+ prandom_u32_max(E * XXX_MAKE_SURE_E_IS_POW2)
|
- ((u64)(E) * get_random_u32() >> 32)
+ prandom_u32_max(E)
|
- ((T)get_random_u32() & ~PAGE_MASK)
+ prandom_u32_max(PAGE_SIZE)
)
@multi_line@
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
identifier RAND;
expression E;
@@
- RAND = get_random_u32();
... when != RAND
- RAND %= (E);
+ RAND = prandom_u32_max(E);
// Find a potential literal
@literal_mask@
expression LITERAL;
type T;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
position p;
@@
((T)get_random_u32()@p & (LITERAL))
// Add one to the literal.
@script:python add_one@
literal << literal_mask.LITERAL;
RESULT;
@@
value = None
if literal.startswith('0x'):
value = int(literal, 16)
elif literal[0] in '123456789':
value = int(literal, 10)
if value is None:
print("I don't know how to handle %s" % (literal))
cocci.include_match(False)
elif value == 2**32 - 1 or value == 2**31 - 1 or value == 2**24 - 1 or value == 2**16 - 1 or value == 2**8 - 1:
print("Skipping 0x%x for cleanup elsewhere" % (value))
cocci.include_match(False)
elif value & (value + 1) != 0:
print("Skipping 0x%x because it's not a power of two minus one" % (value))
cocci.include_match(False)
elif literal.startswith('0x'):
coccinelle.RESULT = cocci.make_expr("0x%x" % (value + 1))
else:
coccinelle.RESULT = cocci.make_expr("%d" % (value + 1))
// Replace the literal mask with the calculated result.
@plus_one@
expression literal_mask.LITERAL;
position literal_mask.p;
expression add_one.RESULT;
identifier FUNC;
@@
- (FUNC()@p & (LITERAL))
+ prandom_u32_max(RESULT)
@collapse_ret@
type T;
identifier VAR;
expression E;
@@
{
- T VAR;
- VAR = (E);
- return VAR;
+ return E;
}
@drop_var@
type T;
identifier VAR;
@@
{
- T VAR;
... when != VAR
}
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: KP Singh <kpsingh@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz> # for ext4 and sbitmap
Reviewed-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com> # for drbd
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com> # for s390
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # for mmc
Acked-by: Darrick J. Wong <djwong@kernel.org> # for xfs
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
The merge of the kbuild tree dropped the renaming of the FSL_BOOKE
kconfig option.
Fixes: 8afc66e8d4 ("Merge tag 'kbuild-v6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild")
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
linux-next for a couple of months without, to my knowledge, any negative
reports (or any positive ones, come to that).
- Also the Maple Tree from Liam R. Howlett. An overlapping range-based
tree for vmas. It it apparently slight more efficient in its own right,
but is mainly targeted at enabling work to reduce mmap_lock contention.
Liam has identified a number of other tree users in the kernel which
could be beneficially onverted to mapletrees.
Yu Zhao has identified a hard-to-hit but "easy to fix" lockdep splat
(https://lkml.kernel.org/r/CAOUHufZabH85CeUN-MEMgL8gJGzJEWUrkiM58JkTbBhh-jew0Q@mail.gmail.com).
This has yet to be addressed due to Liam's unfortunately timed
vacation. He is now back and we'll get this fixed up.
- Dmitry Vyukov introduces KMSAN: the Kernel Memory Sanitizer. It uses
clang-generated instrumentation to detect used-unintialized bugs down to
the single bit level.
KMSAN keeps finding bugs. New ones, as well as the legacy ones.
- Yang Shi adds a userspace mechanism (madvise) to induce a collapse of
memory into THPs.
- Zach O'Keefe has expanded Yang Shi's madvise(MADV_COLLAPSE) to support
file/shmem-backed pages.
- userfaultfd updates from Axel Rasmussen
- zsmalloc cleanups from Alexey Romanov
- cleanups from Miaohe Lin: vmscan, hugetlb_cgroup, hugetlb and memory-failure
- Huang Ying adds enhancements to NUMA balancing memory tiering mode's
page promotion, with a new way of detecting hot pages.
- memcg updates from Shakeel Butt: charging optimizations and reduced
memory consumption.
- memcg cleanups from Kairui Song.
- memcg fixes and cleanups from Johannes Weiner.
- Vishal Moola provides more folio conversions
- Zhang Yi removed ll_rw_block() :(
- migration enhancements from Peter Xu
- migration error-path bugfixes from Huang Ying
- Aneesh Kumar added ability for a device driver to alter the memory
tiering promotion paths. For optimizations by PMEM drivers, DRM
drivers, etc.
- vma merging improvements from Jakub Matěn.
- NUMA hinting cleanups from David Hildenbrand.
- xu xin added aditional userspace visibility into KSM merging activity.
- THP & KSM code consolidation from Qi Zheng.
- more folio work from Matthew Wilcox.
- KASAN updates from Andrey Konovalov.
- DAMON cleanups from Kaixu Xia.
- DAMON work from SeongJae Park: fixes, cleanups.
- hugetlb sysfs cleanups from Muchun Song.
- Mike Kravetz fixes locking issues in hugetlbfs and in hugetlb core.
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Merge tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- Yu Zhao's Multi-Gen LRU patches are here. They've been under test in
linux-next for a couple of months without, to my knowledge, any
negative reports (or any positive ones, come to that).
- Also the Maple Tree from Liam Howlett. An overlapping range-based
tree for vmas. It it apparently slightly more efficient in its own
right, but is mainly targeted at enabling work to reduce mmap_lock
contention.
Liam has identified a number of other tree users in the kernel which
could be beneficially onverted to mapletrees.
Yu Zhao has identified a hard-to-hit but "easy to fix" lockdep splat
at [1]. This has yet to be addressed due to Liam's unfortunately
timed vacation. He is now back and we'll get this fixed up.
- Dmitry Vyukov introduces KMSAN: the Kernel Memory Sanitizer. It uses
clang-generated instrumentation to detect used-unintialized bugs down
to the single bit level.
KMSAN keeps finding bugs. New ones, as well as the legacy ones.
- Yang Shi adds a userspace mechanism (madvise) to induce a collapse of
memory into THPs.
- Zach O'Keefe has expanded Yang Shi's madvise(MADV_COLLAPSE) to
support file/shmem-backed pages.
- userfaultfd updates from Axel Rasmussen
- zsmalloc cleanups from Alexey Romanov
- cleanups from Miaohe Lin: vmscan, hugetlb_cgroup, hugetlb and
memory-failure
- Huang Ying adds enhancements to NUMA balancing memory tiering mode's
page promotion, with a new way of detecting hot pages.
- memcg updates from Shakeel Butt: charging optimizations and reduced
memory consumption.
- memcg cleanups from Kairui Song.
- memcg fixes and cleanups from Johannes Weiner.
- Vishal Moola provides more folio conversions
- Zhang Yi removed ll_rw_block() :(
- migration enhancements from Peter Xu
- migration error-path bugfixes from Huang Ying
- Aneesh Kumar added ability for a device driver to alter the memory
tiering promotion paths. For optimizations by PMEM drivers, DRM
drivers, etc.
- vma merging improvements from Jakub Matěn.
- NUMA hinting cleanups from David Hildenbrand.
- xu xin added aditional userspace visibility into KSM merging
activity.
- THP & KSM code consolidation from Qi Zheng.
- more folio work from Matthew Wilcox.
- KASAN updates from Andrey Konovalov.
- DAMON cleanups from Kaixu Xia.
- DAMON work from SeongJae Park: fixes, cleanups.
- hugetlb sysfs cleanups from Muchun Song.
- Mike Kravetz fixes locking issues in hugetlbfs and in hugetlb core.
Link: https://lkml.kernel.org/r/CAOUHufZabH85CeUN-MEMgL8gJGzJEWUrkiM58JkTbBhh-jew0Q@mail.gmail.com [1]
* tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (555 commits)
hugetlb: allocate vma lock for all sharable vmas
hugetlb: take hugetlb vma_lock when clearing vma_lock->vma pointer
hugetlb: fix vma lock handling during split vma and range unmapping
mglru: mm/vmscan.c: fix imprecise comments
mm/mglru: don't sync disk for each aging cycle
mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol
mm: memcontrol: use do_memsw_account() in a few more places
mm: memcontrol: deprecate swapaccounting=0 mode
mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled
mm/secretmem: remove reduntant return value
mm/hugetlb: add available_huge_pages() func
mm: remove unused inline functions from include/linux/mm_inline.h
selftests/vm: add selftest for MADV_COLLAPSE of uffd-minor memory
selftests/vm: add file/shmem MADV_COLLAPSE selftest for cleared pmd
selftests/vm: add thp collapse shmem testing
selftests/vm: add thp collapse file and tmpfs testing
selftests/vm: modularize thp collapse memory operations
selftests/vm: dedup THP helpers
mm/khugepaged: add tracepoint to hpage_collapse_scan_file()
mm/madvise: add file and shmem support to MADV_COLLAPSE
...
