kernel/linux.git/arch/powerpc/Makefile, branch v6.18.22

kbuild: Add missing $(objtree) prefix to powerpc crtsavres.o artifact

2025-09-01T08:11:57+00:00

In the upstream commit 214c0eea43b2ea66bcd6467ea57e47ce8874191b ("kbuild: add $(objtree)/ prefix to some in-kernel build artifacts") artifacts required for building out-of-tree kernel modules had $(objtree) prepended to them to prepare for building in other directories. When building external modules for powerpc, arch/powerpc/lib/crtsavres.o is required for certain configurations. This artifact is missing the prepended $(objtree). Fixes: 13b25489b6f8 ("kbuild: change working directory to external module directory with M=") Acked-by: Masahiro Yamada Reviewed-by: Nicolas Schier Tested-by: Nicolas Schier Signed-off-by: Kienan Stewart Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20250218-buildfix-extmod-powerpc-v2-1-1e78fcf12b56@efficios.com

arch/powerpc: Remove .interp section in vmlinux

2025-07-22T08:51:19+00:00

When building with CONFIG_RELOCATABLE, there is a .interp section which contains the name of the expected ELF interpreter: Contents of section .interp: c0000000021c1bac 2f757372 2f6c6962 2f6c642e 736f2e31 /usr/lib/ld.so.1 c0000000021c1bbc 00 . That information is useless and even likely wrong. Remove it. Link: https://github.com/linuxppc/issues/issues/434 Signed-off-by: Christophe Leroy Acked-by: Segher Boessenkool Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/eeaf8fd6628a75d19872ab31cf7e7179e2baef5e.1751366959.git.christophe.leroy@csgroup.eu

Merge tag 'kbuild-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2024-11-30T21:41:50+00:00

Pull Kbuild updates from Masahiro Yamada: - Add generic support for built-in boot DTB files - Enable TAB cycling for dialog buttons in nconfig - Fix issues in streamline_config.pl - Refactor Kconfig - Add support for Clang's AutoFDO (Automatic Feedback-Directed Optimization) - Add support for Clang's Propeller, a profile-guided optimization. - Change the working directory to the external module directory for M= builds - Support building external modules in a separate output directory - Enable objtool for *.mod.o and additional kernel objects - Use lz4 instead of deprecated lz4c - Work around a performance issue with "git describe" - Refactor modpost * tag 'kbuild-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (85 commits) kbuild: rename .tmp_vmlinux.kallsyms0.syms to .tmp_vmlinux0.syms gitignore: Don't ignore 'tags' directory kbuild: add dependency from vmlinux to resolve_btfids modpost: replace tdb_hash() with hash_str() kbuild: deb-pkg: add python3:native to build dependency genksyms: reduce indentation in export_symbol() modpost: improve error messages in device_id_check() modpost: rename alias symbol for MODULE_DEVICE_TABLE() modpost: rename variables in handle_moddevtable() modpost: move strstarts() to modpost.h modpost: convert do_usb_table() to a generic handler modpost: convert do_of_table() to a generic handler modpost: convert do_pnp_device_entry() to a generic handler modpost: convert do_pnp_card_entries() to a generic handler modpost: call module_alias_printf() from all do_*_entry() functions modpost: pass (struct module *) to do_*_entry() functions modpost: remove DEF_FIELD_ADDR_VAR() macro modpost: deduplicate MODULE_ALIAS() for all drivers modpost: introduce module_alias_printf() helper modpost: remove unnecessary check in do_acpi_entry() ...

kbuild: add $(objtree)/ prefix to some in-kernel build artifacts

2024-11-27T00:38:27+00:00

$(objtree) refers to the top of the output directory of kernel builds. This commit adds the explicit $(objtree)/ prefix to build artifacts needed for building external modules. This change has no immediate impact, as the top-level Makefile currently defines: objtree := . This commit prepares for supporting the building of external modules in a different directory. Signed-off-by: Masahiro Yamada Reviewed-by: Nicolas Schier

powerpc/Makefile: Allow overriding CPP

2024-11-15T00:59:55+00:00

Unlike all other arches, powerpc doesn't allow the user to override CPP, because it sets it unconditionally in the arch Makefile. This can lead to strange build failures. Instead add the required flags to KBUILD_CPPFLAGS, which are passed to CPP, CC and AS invocations by the generic Makefile logic. Reported-by: Arnd Bergmann Tested-by: Nathan Chancellor Reviewed-by: Nathan Chancellor Closes: https://lore.kernel.org/all/20240607061629.530301-1-arnd@kernel.org Signed-off-by: Arnd Bergmann [mpe: Rebase, write change log, add Arnd's SoB as communicated privately] Signed-off-by: Michael Ellerman Link: https://patch.msgid.link/20241107112646.32401-1-mpe@ellerman.id.au

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: 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/boot: Remove bogus reference to lilo

2024-10-29T12:01:47+00:00

The help text refers to lilo, but the install script does not run lilo and never has. The reference to lilo seems to have come originally from arch/ppc/Makefile, but it was not true there either. Remove it. Reported-by: Thorsten Leemhuis Link: https://fosstodon.org/@kernellogger/113032940928131612 Signed-off-by: Michael Ellerman Link: https://patch.msgid.link/20241009053806.135807-1-mpe@ellerman.id.au

powerpc: Adjust adding stack protector flags to KBUILD_CLAGS for clang

2024-10-23T10:11:55+00:00

After fixing the HAVE_STACKPROTECTER checks for clang's in-progress per-task stack protector support [1], the build fails during prepare0 because '-mstack-protector-guard-offset' has not been added to KBUILD_CFLAGS yet but the other '-mstack-protector-guard' flags have. clang: error: '-mstack-protector-guard=tls' is used without '-mstack-protector-guard-offset', and there is no default clang: error: '-mstack-protector-guard=tls' is used without '-mstack-protector-guard-offset', and there is no default make[4]: *** [scripts/Makefile.build:229: scripts/mod/empty.o] Error 1 make[4]: *** [scripts/Makefile.build:102: scripts/mod/devicetable-offsets.s] Error 1 Mirror other architectures and add all '-mstack-protector-guard' flags to KBUILD_CFLAGS atomically during stack_protector_prepare, which resolves the issue and allows clang's implementation to fully work with the kernel. Cc: stable@vger.kernel.org # 6.1+ Link: https://github.com/llvm/llvm-project/pull/110928 [1] Reviewed-by: Keith Packard Tested-by: Keith Packard Signed-off-by: Nathan Chancellor Signed-off-by: Michael Ellerman Link: https://patch.msgid.link/20241009-powerpc-fix-stackprotector-test-clang-v2-2-12fb86b31857@kernel.org

powerpc: Remove 40x from Kconfig and defconfig

2024-06-28T12:28:47+00:00

Remove 40x from Kconfig, making the code unreachable. Signed-off-by: Michael Ellerman Link: https://msgid.link/20240628121201.130802-3-mpe@ellerman.id.au