linux.git/arch/powerpc/kernel/trace, branch vsnprintf

Merge tag 'powerpc-6.13-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

2024-11-23T18:44:31+00:00

Pull powerpc updates from Michael Ellerman:

 - Rework kfence support for the HPT MMU to work on systems with >= 16TB
   of RAM.

 - Remove the powerpc "maple" platform, used by the "Yellow Dog
   Powerstation".

 - Add support for DYNAMIC_FTRACE_WITH_CALL_OPS,
   DYNAMIC_FTRACE_WITH_DIRECT_CALLS & BPF Trampolines.

 - Add support for running KVM nested guests on Power11.

 - Other small features, cleanups and fixes.

Thanks to Amit Machhiwal, Arnd Bergmann, Christophe Leroy, Costa
Shulyupin, David Hunter, David Wang, Disha Goel, Gautam Menghani, Geert
Uytterhoeven, Hari Bathini, Julia Lawall, Kajol Jain, Keith Packard,
Lukas Bulwahn, Madhavan Srinivasan, Markus Elfring, Michal Suchanek,
Ming Lei, Mukesh Kumar Chaurasiya, Nathan Chancellor, Naveen N Rao,
Nicholas Piggin, Nysal Jan K.A, Paulo Miguel Almeida, Pavithra Prakash,
Ritesh Harjani (IBM), Rob Herring (Arm), Sachin P Bappalige, Shen
Lichuan, Simon Horman, Sourabh Jain, Thomas Weißschuh, Thorsten Blum,
Thorsten Leemhuis, Venkat Rao Bagalkote, Zhang Zekun, and zhang jiao.

* tag 'powerpc-6.13-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (89 commits)
  EDAC/powerpc: Remove PPC_MAPLE drivers
  powerpc/perf: Add per-task/process monitoring to vpa_pmu driver
  powerpc/kvm: Add vpa latency counters to kvm_vcpu_arch
  docs: ABI: sysfs-bus-event_source-devices-vpa-pmu: Document sysfs event format entries for vpa_pmu
  powerpc/perf: Add perf interface to expose vpa counters
  MAINTAINERS: powerpc: Mark Maddy as "M"
  powerpc/Makefile: Allow overriding CPP
  powerpc-km82xx.c: replace of_node_put() with __free
  ps3: Correct some typos in comments
  powerpc/kexec: Fix return of uninitialized variable
  macintosh: Use common error handling code in via_pmu_led_init()
  powerpc/powermac: Use of_property_match_string() in pmac_has_backlight_type()
  powerpc: remove dead config options for MPC85xx platform support
  powerpc/xive: Use cpumask_intersects()
  selftests/powerpc: Remove the path after initialization.
  powerpc/xmon: symbol lookup length fixed
  powerpc/ep8248e: Use %pa to format resource_size_t
  powerpc/ps3: Reorganize kerneldoc parameter names
  KVM: PPC: Book3S HV: Fix kmv -> kvm typo
  powerpc/sstep: make emulate_vsx_load and emulate_vsx_store static
  ...

Merge tag 'mm-stable-2024-11-18-19-27' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2024-11-23T17:58:07+00:00

Pull MM updates from Andrew Morton:

- The series "zram: optimal post-processing target selection" from
Sergey Senozhatsky improves zram's post-processing selection
algorithm. This leads to improved memory savings.

- Wei Yang has gone to town on the mapletree code, contributing several
series which clean up the implementation:
- "refine mas_mab_cp()"
- "Reduce the space to be cleared for maple_big_node"
- "maple_tree: simplify mas_push_node()"
- "Following cleanup after introduce mas_wr_store_type()"
- "refine storing null"

- The series "selftests/mm: hugetlb_fault_after_madv improvements" from
David Hildenbrand fixes this selftest for s390.

- The series "introduce pte_offset_map_{ro|rw}_nolock()" from Qi Zheng
implements some rationaizations and cleanups in the page mapping
code.

- The series "mm: optimize shadow entries removal" from Shakeel Butt
optimizes the file truncation code by speeding up the handling of
shadow entries.

- The series "Remove PageKsm()" from Matthew Wilcox completes the
migration of this flag over to being a folio-based flag.

- The series "Unify hugetlb into arch_get_unmapped_area functions" from
Oscar Salvador implements a bunch of consolidations and cleanups in
the hugetlb code.

- The series "Do not shatter hugezeropage on wp-fault" from Dev Jain
takes away the wp-fault time practice of turning a huge zero page
into small pages. Instead we replace the whole thing with a THP. More
consistent cleaner and potentiall saves a large number of pagefaults.

- The series "percpu: Add a test case and fix for clang" from Andy
Shevchenko enhances and fixes the kernel's built in percpu test code.

- The series "mm/mremap: Remove extra vma tree walk" from Liam Howlett
optimizes mremap() by avoiding doing things which we didn't need to
do.

- The series "Improve the tmpfs large folio read performance" from
Baolin Wang teaches tmpfs to copy data into userspace at the folio
size rather than as individual pages. A 20% speedup was observed.

- The series "mm/damon/vaddr: Fix issue in
damon_va_evenly_split_region()" fro Zheng Yejian fixes DAMON
splitting.

- The series "memcg-v1: fully deprecate charge moving" from Shakeel
Butt removes the long-deprecated memcgv2 charge moving feature.

- The series "fix error handling in mmap_region() and refactor" from
Lorenzo Stoakes cleanup up some of the mmap() error handling and
addresses some potential performance issues.

- The series "x86/module: use large ROX pages for text allocations"
from Mike Rapoport teaches x86 to use large pages for
read-only-execute module text.

- The series "page allocation tag compression" from Suren Baghdasaryan
is followon maintenance work for the new page allocation profiling
feature.

- The series "page->index removals in mm" from Matthew Wilcox remove
most references to page->index in mm/. A slow march towards shrinking
struct page.

- The series "damon/{self,kunit}tests: minor fixups for DAMON debugfs
interface tests" from Andrew Paniakin performs maintenance work for
DAMON's self testing code.

- The series "mm: zswap swap-out of large folios" from Kanchana Sridhar
improves zswap's batching of compression and decompression. It is a
step along the way towards using Intel IAA hardware acceleration for
this zswap operation.

- The series "kasan: migrate the last module test to kunit" from
Sabyrzhan Tasbolatov completes the migration of the KASAN built-in
tests over to the KUnit framework.

- The series "implement lightweight guard pages" from Lorenzo Stoakes
permits userapace to place fault-generating guard pages within a
single VMA, rather than requiring that multiple VMAs be created for
this. Improved efficiencies for userspace memory allocators are
expected.

- The series "memcg: tracepoint for flushing stats" from JP Kobryn uses
tracepoints to provide increased visibility into memcg stats flushing
activity.

- The series "zram: IDLE flag handling fixes" from Sergey Senozhatsky
fixes a zram buglet which potentially affected performance.

- The series "mm: add more kernel parameters to control mTHP" from
Maíra Canal enhances our ability to control/configuremultisize THP
from the kernel boot command line.

- The series "kasan: few improvements on kunit tests" from Sabyrzhan
Tasbolatov has a couple of fixups for the KASAN KUnit tests.

- The series "mm/list_lru: Split list_lru lock into per-cgroup scope"
from Kairui Song optimizes list_lru memory utilization when lockdep
is enabled.

* tag 'mm-stable-2024-11-18-19-27' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (215 commits)
cma: enforce non-zero pageblock_order during cma_init_reserved_mem()
mm/kfence: add a new kunit test test_use_after_free_read_nofault()
zram: fix NULL pointer in comp_algorithm_show()
memcg/hugetlb: add hugeTLB counters to memcg
vmstat: call fold_vm_zone_numa_events() before show per zone NUMA event
mm: mmap_lock: check trace_mmap_lock_$type_enabled() instead of regcount
zram: ZRAM_DEF_COMP should depend on ZRAM
MAINTAINERS/MEMORY MANAGEMENT: add document files for mm
Docs/mm/damon: recommend academic papers to read and/or cite
mm: define general function pXd_init()
kmemleak: iommu/iova: fix transient kmemleak false positive
mm/list_lru: simplify the list_lru walk callback function
mm/list_lru: split the lock to per-cgroup scope
mm/list_lru: simplify reparenting and initial allocation
mm/list_lru: code clean up for reparenting
mm/list_lru: don't export list_lru_add
mm/list_lru: don't pass unnecessary key parameters
kasan: add kunit tests for kmalloc_track_caller, kmalloc_node_track_caller
kasan: change kasan_atomics kunit test as KUNIT_CASE_SLOW
kasan: use EXPORT_SYMBOL_IF_KUNIT to export symbols
...

asm-generic: introduce text-patching.h

2024-11-07T22:25:15+00:00

Several architectures support text patching, but they name the header
files that declare patching functions differently.

Make all such headers consistently named text-patching.h and add an empty
header in asm-generic for architectures that do not support text patching.

Link: https://lkml.kernel.org/r/20241023162711.2579610-4-rppt@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) 
Reviewed-by: Christoph Hellwig 
Acked-by: Geert Uytterhoeven  # m68k
Acked-by: Arnd Bergmann 
Reviewed-by: Luis Chamberlain 
Tested-by: kdevops 
Cc: Andreas Larsson 
Cc: Andy Lutomirski 
Cc: Ard Biesheuvel 
Cc: Borislav Petkov (AMD) 
Cc: Brian Cain 
Cc: Catalin Marinas 
Cc: Christophe Leroy 
Cc: Dave Hansen 
Cc: Dinh Nguyen 
Cc: Guo Ren 
Cc: Helge Deller 
Cc: Huacai Chen 
Cc: Ingo Molnar 
Cc: Johannes Berg 
Cc: John Paul Adrian Glaubitz 
Cc: Kent Overstreet 
Cc: Liam R. Howlett 
Cc: Mark Rutland 
Cc: Masami Hiramatsu (Google) 
Cc: Matt Turner 
Cc: Max Filippov 
Cc: Michael Ellerman 
Cc: Michal Simek 
Cc: Oleg Nesterov 
Cc: Palmer Dabbelt 
Cc: Peter Zijlstra 
Cc: Richard Weinberger 
Cc: Russell King 
Cc: Song Liu 
Cc: Stafford Horne 
Cc: Steven Rostedt (Google) 
Cc: Suren Baghdasaryan 
Cc: Thomas Bogendoerfer 
Cc: Thomas Gleixner 
Cc: Uladzislau Rezki (Sony) 
Cc: Vineet Gupta 
Cc: Will Deacon 
Signed-off-by: Andrew Morton

powerpc/ftrace: Add support for DYNAMIC_FTRACE_WITH_DIRECT_CALLS

2024-10-31T00:00:55+00:00

Add support for DYNAMIC_FTRACE_WITH_DIRECT_CALLS similar to the arm64
implementation.

ftrace direct calls allow custom trampolines to be called into directly
from function ftrace call sites, bypassing the ftrace trampoline
completely. This functionality is currently utilized by BPF trampolines
to hook into kernel function entries.

Since we have limited relative branch range, we support ftrace direct
calls through support for DYNAMIC_FTRACE_WITH_CALL_OPS. In this
approach, ftrace trampoline is not entirely bypassed. Rather, it is
re-purposed into a stub that reads direct_call field from the associated
ftrace_ops structure and branches into that, if it is not NULL. For
this, it is sufficient if we can ensure that the ftrace trampoline is
reachable from all traceable functions.

When multiple ftrace_ops are associated with a call site, we utilize a
call back to set pt_regs->orig_gpr3 that can then be tested on the
return path from the ftrace trampoline to branch into the direct caller.

Signed-off-by: Naveen N Rao 
Signed-off-by: Michael Ellerman 
Link: https://patch.msgid.link/20241030070850.1361304-16-hbathini@linux.ibm.com

powerpc/ftrace: Add support for DYNAMIC_FTRACE_WITH_CALL_OPS

2024-10-31T00:00:55+00:00

Implement support for DYNAMIC_FTRACE_WITH_CALL_OPS similar to the
arm64 implementation.

This works by patching-in a pointer to an associated ftrace_ops
structure before each traceable function. If multiple ftrace_ops are
associated with a call site, then a special ftrace_list_ops is used to
enable iterating over all the registered ftrace_ops. If no ftrace_ops
are associated with a call site, then a special ftrace_nop_ops structure
is used to render the ftrace call as a no-op. ftrace trampoline can then
read the associated ftrace_ops for a call site by loading from an offset
from the LR, and branch directly to the associated function.

The primary advantage with this approach is that we don't have to
iterate over all the registered ftrace_ops for call sites that have a
single ftrace_ops registered. This is the equivalent of implementing
support for dynamic ftrace trampolines, which set up a special ftrace
trampoline for each registered ftrace_ops and have individual call sites
branch into those directly.

A secondary advantage is that this gives us a way to add support for
direct ftrace callers without having to resort to using stubs. The
address of the direct call trampoline can be loaded from the ftrace_ops
structure.

To support this, we reserve a nop before each function on 32-bit
powerpc. For 64-bit powerpc, two nops are reserved before each
out-of-line stub. During ftrace activation, we update this location with
the associated ftrace_ops pointer. Then, on ftrace entry, we load from
this location and call into ftrace_ops->func().

For 64-bit powerpc, we ensure that the out-of-line stub area is
doubleword aligned so that ftrace_ops address can be updated atomically.

Signed-off-by: Naveen N Rao 
Signed-off-by: Michael Ellerman 
Link: https://patch.msgid.link/20241030070850.1361304-15-hbathini@linux.ibm.com

powerpc64/ftrace: Support .text larger than 32MB with out-of-line stubs

2024-10-31T00:00:55+00:00

We are restricted to a .text size of ~32MB when using out-of-line
function profile sequence. Allow this to be extended up to the previous
limit of ~64MB by reserving space in the middle of .text.

A new config option CONFIG_PPC_FTRACE_OUT_OF_LINE_NUM_RESERVE is
introduced to specify the number of function stubs that are reserved in
.text. On boot, ftrace utilizes stubs from this area first before using
the stub area at the end of .text.

A ppc64le defconfig has ~44k functions that can be traced. A more
conservative value of 32k functions is chosen as the default value of
PPC_FTRACE_OUT_OF_LINE_NUM_RESERVE so that we do not allot more space
than necessary by default. If building a kernel that only has 32k
trace-able functions, we won't allot any more space at the end of .text
during the pass on vmlinux.o. Otherwise, only the remaining functions
get space for stubs at the end of .text. This default value should help
cover a .text size of ~48MB in total (including space reserved at the
end of .text which can cover up to 32MB), which should be sufficient for
most common builds. For a very small kernel build, this can be set to 0.
Or, this can be bumped up to a larger value to support vmlinux .text
size up to ~64MB.

Signed-off-by: Naveen N Rao 
Signed-off-by: Hari Bathini 
Signed-off-by: Michael Ellerman 
Link: https://patch.msgid.link/20241030070850.1361304-14-hbathini@linux.ibm.com

powerpc64/ftrace: Move ftrace sequence out of line

2024-10-31T00:00:54+00:00

Function profile sequence on powerpc includes two instructions at the
beginning of each function:
	mflr	r0
	bl	ftrace_caller

The call to ftrace_caller() gets nop'ed out during kernel boot and is
patched in when ftrace is enabled.

Given the sequence, we cannot return from ftrace_caller with 'blr' as we
need to keep LR and r0 intact. This results in link stack (return
address predictor) imbalance when ftrace is enabled. To address that, we
would like to use a three instruction sequence:
	mflr	r0
	bl	ftrace_caller
	mtlr	r0

Further more, to support DYNAMIC_FTRACE_WITH_CALL_OPS, we need to
reserve two instruction slots before the function. This results in a
total of five instruction slots to be reserved for ftrace use on each
function that is traced.

Move the function profile sequence out-of-line to minimize its impact.
To do this, we reserve a single nop at function entry using
-fpatchable-function-entry=1 and add a pass on vmlinux.o to determine
the total number of functions that can be traced. This is then used to
generate a .S file reserving the appropriate amount of space for use as
ftrace stubs, which is built and linked into vmlinux.

On bootup, the stub space is split into separate stubs per function and
populated with the proper instruction sequence. A pointer to the
associated stub is maintained in dyn_arch_ftrace.

For modules, space for ftrace stubs is reserved from the generic module
stub space.

This is restricted to and enabled by default only on 64-bit powerpc,
though there are some changes to accommodate 32-bit powerpc. This is
done so that 32-bit powerpc could choose to opt into this based on
further tests and benchmarks.

As an example, after this patch, kernel functions will have a single nop
at function entry:
:
	addis	r2,r12,467
	addi	r2,r2,-16028
	nop
	mfocrf	r11,8
	...

When ftrace is enabled, the nop is converted to an unconditional branch
to the stub associated with that function:
:
	addis	r2,r12,467
	addi	r2,r2,-16028
	b	ftrace_ool_stub_text_end+0x11b28
	mfocrf	r11,8
	...

The associated stub:
:
	mflr	r0
	bl	ftrace_caller
	mtlr	r0
	b	kernel_clone+0xc
	...

This change showed an improvement of ~10% in null_syscall benchmark on a
Power 10 system with ftrace enabled.

Signed-off-by: Naveen N Rao 
Signed-off-by: Hari Bathini 
Signed-off-by: Michael Ellerman 
Link: https://patch.msgid.link/20241030070850.1361304-13-hbathini@linux.ibm.com

powerpc/ftrace: Skip instruction patching if the instructions are the same

2024-10-31T00:00:53+00:00

To simplify upcoming changes to ftrace, add a check to skip actual
instruction patching if the old and new instructions are the same. We
still validate that the instruction is what we expect, but don't
actually patch the same instruction again.

Signed-off-by: Naveen N Rao 
Signed-off-by: Michael Ellerman 
Link: https://patch.msgid.link/20241030070850.1361304-8-hbathini@linux.ibm.com

powerpc/ftrace: Remove pointer to struct module from dyn_arch_ftrace

2024-10-31T00:00:53+00:00

Pointer to struct module is only relevant for ftrace records belonging
to kernel modules. Having this field in dyn_arch_ftrace wastes memory
for all ftrace records belonging to the kernel. Remove the same in
favour of looking up the module from the ftrace record address, similar
to other architectures.

Reviewed-by: Nicholas Piggin 
Signed-off-by: Naveen N Rao 
Signed-off-by: Michael Ellerman 
Link: https://patch.msgid.link/20241030070850.1361304-7-hbathini@linux.ibm.com

powerpc32/ftrace: Unify 32-bit and 64-bit ftrace entry code

2024-10-31T00:00:53+00:00

On 32-bit powerpc, gcc generates a three instruction sequence for
function profiling:
	mflr	r0
	stw	r0, 4(r1)
	bl	_mcount

On kernel boot, the call to _mcount() is nop-ed out, to be patched back
in when ftrace is actually enabled. The 'stw' instruction therefore is
not necessary unless ftrace is enabled. Nop it out during ftrace init.

When ftrace is enabled, we want the 'stw' so that stack unwinding works
properly. Perform the same within the ftrace handler, similar to 64-bit
powerpc.

Reviewed-by: Nicholas Piggin 
Signed-off-by: Naveen N Rao 
Signed-off-by: Michael Ellerman 
Link: https://patch.msgid.link/20241030070850.1361304-5-hbathini@linux.ibm.com