linux.git/arch/powerpc/kernel/trace, branch v6.6

Merge tag 'powerpc-6.6-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

2023-08-31T19:43:10+00:00

Pull powerpc updates from Michael Ellerman:

 - Add HOTPLUG_SMT support (/sys/devices/system/cpu/smt) and honour the
   configured SMT state when hotplugging CPUs into the system

 - Combine final TLB flush and lazy TLB mm shootdown IPIs when using the
   Radix MMU to avoid a broadcast TLBIE flush on exit

 - Drop the exclusion between ptrace/perf watchpoints, and drop the now
   unused associated arch hooks

 - Add support for the "nohlt" command line option to disable CPU idle

 - Add support for -fpatchable-function-entry for ftrace, with GCC >=
   13.1

 - Rework memory block size determination, and support 256MB size on
   systems with GPUs that have hotpluggable memory

 - Various other small features and fixes

Thanks to Andrew Donnellan, Aneesh Kumar K.V, Arnd Bergmann, Athira
Rajeev, Benjamin Gray, Christophe Leroy, Frederic Barrat, Gautam
Menghani, Geoff Levand, Hari Bathini, Immad Mir, Jialin Zhang, Joel
Stanley, Jordan Niethe, Justin Stitt, Kajol Jain, Kees Cook, Krzysztof
Kozlowski, Laurent Dufour, Liang He, Linus Walleij, Mahesh Salgaonkar,
Masahiro Yamada, Michal Suchanek, Nageswara R Sastry, Nathan Chancellor,
Nathan Lynch, Naveen N Rao, Nicholas Piggin, Nick Desaulniers, Omar
Sandoval, Randy Dunlap, Reza Arbab, Rob Herring, Russell Currey, Sourabh
Jain, Thomas Gleixner, Trevor Woerner, Uwe Kleine-König, Vaibhav Jain,
Xiongfeng Wang, Yuan Tan, Zhang Rui, and Zheng Zengkai.

* tag 'powerpc-6.6-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (135 commits)
  macintosh/ams: linux/platform_device.h is needed
  powerpc/xmon: Reapply "Relax frame size for clang"
  powerpc/mm/book3s64: Use 256M as the upper limit with coherent device memory attached
  powerpc/mm/book3s64: Fix build error with SPARSEMEM disabled
  powerpc/iommu: Fix notifiers being shared by PCI and VIO buses
  powerpc/mpc5xxx: Add missing fwnode_handle_put()
  powerpc/config: Disable SLAB_DEBUG_ON in skiroot
  powerpc/pseries: Remove unused hcall tracing instruction
  powerpc/pseries: Fix hcall tracepoints with JUMP_LABEL=n
  powerpc: dts: add missing space before {
  powerpc/eeh: Use pci_dev_id() to simplify the code
  powerpc/64s: Move CPU -mtune options into Kconfig
  powerpc/powermac: Fix unused function warning
  powerpc/pseries: Rework lppaca_shared_proc() to avoid DEBUG_PREEMPT
  powerpc: Don't include lppaca.h in paca.h
  powerpc/pseries: Move hcall_vphn() prototype into vphn.h
  powerpc/pseries: Move VPHN constants into vphn.h
  cxl: Drop unused detach_spa()
  powerpc: Drop zalloc_maybe_bootmem()
  powerpc/powernv: Use struct opal_prd_msg in more places
  ...

powerpc/ftrace: Add support for -fpatchable-function-entry

2023-08-21T14:09:06+00:00

GCC v13.1 updated support for -fpatchable-function-entry on ppc64le to
emit nops after the local entry point, rather than before it. This
allows us to use this in the kernel for ftrace purposes. A new script is
added under arch/powerpc/tools/ to help detect if nops are emitted after
the function local entry point, or before the global entry point.

With -fpatchable-function-entry, we no longer have the profiling
instructions generated at function entry, so we only need to validate
the presence of two nops at the ftrace location in ftrace_init_nop(). We
patch the preceding instruction with 'mflr r0' to match the
-mprofile-kernel ABI for subsequent ftrace use.

This changes the profiling instructions used on ppc32. The default -pg
option emits an additional 'stw' instruction after 'mflr r0' and before
the branch to _mcount 'bl _mcount'. This is very similar to the original
-mprofile-kernel implementation on ppc64le, where an additional 'std'
instruction was used to save LR to its save location in the caller's
stackframe. Subsequently, this additional store was removed in later
compiler versions for performance reasons. The same reasons apply for
ppc32 so we only patch in a 'mflr r0'.

Signed-off-by: Naveen N Rao 
Reviewed-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/68586d22981a2c3bb45f27a2b621173d10a7d092.1687166935.git.naveen@kernel.org

powerpc/ftrace: Implement ftrace_replace_code()

2023-08-21T14:09:06+00:00

Implement ftrace_replace_code() to consolidate logic from the different
ftrace patching routines: ftrace_make_nop(), ftrace_make_call() and
ftrace_modify_call(). Note that ftrace_make_call() is still required
primarily to handle patching modules during their load time. The other
two routines should no longer be called.

This lays the groundwork to enable better control in patching ftrace
locations, including the ability to nop-out preceding profiling
instructions when ftrace is disabled.

Signed-off-by: Naveen N Rao 
Reviewed-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/c28f852225646b0561bbf3c1d22d03f041ace8e0.1687166935.git.naveen@kernel.org

powerpc/ftrace: Replace use of ftrace_call_replace() with ftrace_create_branch_inst()

2023-08-21T14:09:06+00:00

ftrace_create_branch_inst() is clearer about its intent than
ftrace_call_replace().

Signed-off-by: Naveen N Rao 
Reviewed-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/953513b88fa922ba7a66d772dc1310710efe9177.1687166935.git.naveen@kernel.org

powerpc/ftrace: Simplify ftrace_modify_call()

2023-08-21T14:09:06+00:00

Now that we validate the ftrace location during initialization in
ftrace_init_nop(), we can simplify ftrace_modify_call() to patch-in the
updated branch instruction without worrying about the instructions
surrounding the ftrace location. Note that we continue to ensure we
have the expected branch instruction at the ftrace location before
patching it with the updated branch destination.

Signed-off-by: Naveen N Rao 
Reviewed-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/06275720939f8ee4c2f61c9e9a3e89b1fa3c441d.1687166935.git.naveen@kernel.org

powerpc/ftrace: Simplify ftrace_make_call()

2023-08-21T14:09:06+00:00

Now that we validate the ftrace location during initialization in
ftrace_init_nop(), we can simplify ftrace_make_call() to replace the nop
without worrying about the instructions surrounding the ftrace location.
Note that we continue to ensure that we have a nop at the ftrace
location before patching it.

Signed-off-by: Naveen N Rao 
Reviewed-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/2d28866d2f556488a663981abe5621511efb207b.1687166935.git.naveen@kernel.org

powerpc/ftrace: Simplify ftrace_make_nop()

2023-08-21T14:09:06+00:00

Now that we validate the ftrace location during initialization in
ftrace_init_nop(), we can simplify ftrace_make_nop() to patch-in the nop
without worrying about the instructions surrounding the ftrace location.
Note that we continue to ensure that we have a bl to
ftrace_[regs_]caller at the ftrace location before nop-ing it out.

Signed-off-by: Naveen N Rao 
Reviewed-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/e12ccbf28c50c3a07fb614f4d392e55f7098a729.1687166935.git.naveen@kernel.org

powerpc/ftrace: Add separate ftrace_init_nop() with additional validation

2023-08-21T14:09:06+00:00

Currently, we validate instructions around the ftrace location every
time we have to enable/disable ftrace. Introduce ftrace_init_nop() to
instead perform all the validation during ftrace initialization. This
allows us to simply patch the necessary instructions during
enabling/disabling ftrace.

Signed-off-by: Naveen N Rao 
Reviewed-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/f373684081e8e98be09b7f44d2d93069768324dc.1687166935.git.naveen@kernel.org

powerpc/ftrace: Stop re-purposing linker generated long branches for ftrace

2023-08-21T14:09:06+00:00

Commit 67361cf8071286 ("powerpc/ftrace: Handle large kernel configs")
added ftrace support for ppc64 kernel images with a text section larger
than 32MB. The patch did two things:
1. Add stubs at the end of .text to branch into ftrace_[regs_]caller for
   functions that were out of branch range.
2. Re-purpose linker-generated long branches to _mcount to instead branch
   to ftrace_[regs_]caller.

Before that, we only supported kernel .text up to ~32MB. With the above,
we now support up to ~96MB:
- The first 32MB of kernel text can branch directly into
  ftrace_[regs_]caller since that symbol is usually at the beginning.
- The modified long_branch from (2) above is used by the next 32MB of
  kernel text.
- The next 32MB of kernel text can use the stub at the end of text to
  branch back to ftrace_[regs_]caller.

While re-purposing the long branch works in practice, it still restricts
ftrace to kernel text up to ~96MB. The stub at the end of kernel text
from (1) already enables us to extend ftrace support for kernel text
up to 64MB, which fulfils the original requirement. Further, once we
switch to -fpatchable-function-entry, there will not be a long branch
that we can use.

Stop re-purposing the linker-generated long branches for ftrace to
simplify the code. If there are good reasons to support ftrace on
kernels beyond 64MB, we can consider adding support by using
-fpatchable-function-entry.

Signed-off-by: Naveen N Rao 
Reviewed-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/33fa3be97f8e1f2171254ef2e1b0d5c8836c11fd.1687166935.git.naveen@kernel.org

powerpc/ftrace: Refactor ftrace_modify_code()

2023-08-21T14:09:05+00:00

Split up ftrace_modify_code() into a few helpers for future use. Also
update error messages accordingly.

Signed-off-by: Naveen N Rao 
Reviewed-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/a8daa49712b44ff539e6c22a2ea649a540386798.1687166935.git.naveen@kernel.org