Changes in Kbuild

eec37961 - powerpc64/ftrace: Move ftrace sequence out of line

Wed, 30 Oct 2024 07:08:45 +0000

powerpc64/ftrace: Move ftrace sequence out of lineFunction profile sequence on powerpc includes two instructions at thebeginning of each function: mflr r0 bl ftrace_callerThe call to ftrace_caller() gets nop'ed out during kernel boot and ispatched in when ftrace is enabled.Given the sequence, we cannot return from ftrace_caller with 'blr' as weneed to keep LR and r0 intact. This results in link stack (returnaddress predictor) imbalance when ftrace is enabled. To address that, wewould like to use a three instruction sequence: mflr r0 bl ftrace_caller mtlr r0Further more, to support DYNAMIC_FTRACE_WITH_CALL_OPS, we need toreserve two instruction slots before the function. This results in atotal of five instruction slots to be reserved for ftrace use on eachfunction 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 determinethe total number of functions that can be traced. This is then used togenerate a .S file reserving the appropriate amount of space for use asftrace stubs, which is built and linked into vmlinux.On bootup, the stub space is split into separate stubs per function andpopulated with the proper instruction sequence. A pointer to theassociated stub is maintained in dyn_arch_ftrace.For modules, space for ftrace stubs is reserved from the generic modulestub 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 isdone so that 32-bit powerpc could choose to opt into this based onfurther tests and benchmarks.As an example, after this patch, kernel functions will have a single nopat 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 branchto 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 aPower 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 List of files: /linux-6.15/arch/powerpc/Kbuild

8884fc91 - powerpc: Fix fatal warnings flag for LLVM's integrated assembler

Fri, 05 Apr 2024 19:31:22 +0000

powerpc: Fix fatal warnings flag for LLVM's integrated assemblerWhen building with LLVM_IAS=1, there is an error because'-fatal-warnings' is not recognized as a valid flag: clang: error: unsupported argument '-fatal-warnings' to option '-Wa,'Use the double hyphen version of the flag, '--fatal-warnings', whichworks with both the GNU assembler and LLVM's integrated assembler.Fixes: 608d4a5ca563 ("powerpc: Error on assembly warnings")Signed-off-by: Nathan Chancellor Reviewed-by: Justin Stitt Signed-off-by: Michael Ellerman Link: https://msgid.link/20240405-ppc-fix-wa-fatal-warnings-clang-v1-1-bdcd969f2ef0@kernel.org List of files: /linux-6.15/arch/powerpc/Kbuild

608d4a5c - powerpc: Error on assembly warnings

Tue, 26 Mar 2024 04:44:20 +0000

powerpc: Error on assembly warningsWe currently enable -Werror on the arch/powerpc subtree. However thisonly catches C warnings. Assembly warnings are logged, but the makeinvocation will still succeed. This can allow incorrect syntax such as ori r3, r4, r5to be compiled without catching that the assembler is treating r5as the immediate value 5.To prevent this in assembly files and inline assembly, add the-fatal-warnings option to assembler invocations.Signed-off-by: Benjamin Gray Tested-by: Andrew Donnellan Reviewed-by: Andrew Donnellan Signed-off-by: Michael Ellerman Link: https://msgid.link/20240326044420.577031-1-bgray@linux.ibm.com List of files: /linux-6.15/arch/powerpc/Kbuild

8212f898 - kbuild: use more subdir- for visiting subdirectories while cleaning

Wed, 13 Oct 2021 06:36:22 +0000

kbuild: use more subdir- for visiting subdirectories while cleaningDocumentation/kbuild/makefiles.rst suggests to use "archclean" forcleaning arch/$(SRCARCH)/boot/, but it is not a hard requirement.Since commit d92cc4d51643 ("kbuild: require all architectures to havearch/$(SRCARCH)/Kbuild"), we can use the "subdir- += boot" trick forall architectures. This can take advantage of the parallel option (-j)for "make clean".I also cleaned up the comments in arch/$(SRCARCH)/Makefile. The "archdep"target no longer exists.Signed-off-by: Masahiro Yamada Reviewed-by: Kees Cook Acked-by: Geert Uytterhoeven Acked-by: Michael Ellerman (powerpc) List of files: /linux-6.15/arch/powerpc/Kbuild

793b08e2 - powerpc/kexec: Move kexec files into a dedicated subdir.

Tue, 29 Oct 2019 12:13:58 +0000

powerpc/kexec: Move kexec files into a dedicated subdir.arch/powerpc/kernel/ contains 8 files dedicated to kexec.Move them into a dedicated subdirectory.Signed-off-by: Christophe Leroy [mpe: Move to a/p/kexec, drop the 'machine' naming and use 'core' instead]Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/afbef97ec6a978574a5cf91a4441000e0a9da42a.1572351221.git.christophe.leroy@c-s.fr List of files: /linux-6.15/arch/powerpc/Kbuild

96ac6d43 - treewide: Add SPDX license identifier - Kbuild

Thu, 30 May 2019 12:03:44 +0000

treewide: Add SPDX license identifier - KbuildAdd SPDX license identifiers to all Make/Kconfig files which: - Have no license information of any formThese files fall under the project license, GPL v2 only. The resulting SPDXlicense identifier is: GPL-2.0Reported-by: Masahiro Yamada Signed-off-by: Greg Kroah-Hartman Reviewed-by: Kate Stewart Signed-off-by: Greg Kroah-Hartman List of files: /linux-6.15/arch/powerpc/Kbuild

23ad1a27 - powerpc: Add -Werror at arch/powerpc level

Wed, 10 Oct 2018 05:13:06 +0000

powerpc: Add -Werror at arch/powerpc levelBack when I added -Werror in commit ba55bd74360e ("powerpc: Addconfigurable -Werror for arch/powerpc") I did it by adding it to mostof the arch Makefiles.At the time we excluded math-emu, because apparently it didn't buildcleanly. But that seems to have been fixed somewhere in the interim.So move the -Werror addition to the top-level of the arch, this savesus from repeating it in every Makefile and means we won't forget toadd it to any new sub-dirs.Signed-off-by: Michael Ellerman List of files: /linux-6.15/arch/powerpc/Kbuild

c47ca98d - powerpc: Move core kernel logic into arch/powerpc/Kbuild

Wed, 10 Oct 2018 05:13:05 +0000

powerpc: Move core kernel logic into arch/powerpc/KbuildThis is a nice cleanup, arch/powerpc/Makefile is long and messy somoving this out helps a little.It also allows us to do: $ make arch/powerpcWhich can be helpful if you just want to compile test some changes toarch code and not link everything.Finally it also gives us a single place to do subdir-cc-flagsassignments which affect the whole of arch/powerpc, which we will doin a future patch.Signed-off-by: Michael Ellerman List of files: /linux-6.15/arch/powerpc/Kbuild