kernel/arch/powerpc/include/asm/head-64.h, branch linux-6.2.y

powerpc/64/asm: Do not reassign labels

2021-12-23T11:35:12Z

The LLVM integrated assembler really does not like us reassigning things to the same label: :7:9: error: invalid reassignment of non-absolute variable 'fs_label' This happens across a bunch of platforms: https://github.com/ClangBuiltLinux/linux/issues/1043 https://github.com/ClangBuiltLinux/linux/issues/1008 https://github.com/ClangBuiltLinux/linux/issues/920 https://github.com/ClangBuiltLinux/linux/issues/1050 There is no hope of getting this fixed in LLVM (see https://github.com/ClangBuiltLinux/linux/issues/1043#issuecomment-641571200 and https://bugs.llvm.org/show_bug.cgi?id=47798#c1 ) so if we want to build with LLVM_IAS, we need to hack around it ourselves. For us the big problem comes from this: \#define USE_FIXED_SECTION(sname) \ fs_label = start_##sname; \ fs_start = sname##_start; \ use_ftsec sname; \#define USE_TEXT_SECTION() fs_label = start_text; \ fs_start = text_start; \ .text and in particular fs_label. This works around it by not setting those 'variables' and requiring that users of the variables instead track for themselves what section they are in. This isn't amazing, by any stretch, but it gets us further in the compilation. Note that even though users have to keep track of the section, using a wrong one produces an error with both binutils and llvm which prevents from using wrong section at the compile time: llvm error example: AS arch/powerpc/kernel/head_64.o :0: error: Cannot represent a difference across sections make[3]: *** [/home/aik/p/kernels-llvm/llvm/scripts/Makefile.build:388: arch/powerpc/kernel/head_64.o] Error 1 binutils error example: /home/aik/p/kernels-llvm/llvm/arch/powerpc/kernel/exceptions-64s.S: Assembler messages: /home/aik/p/kernels-llvm/llvm/arch/powerpc/kernel/exceptions-64s.S:1974: Error: can't resolve `system_call_common' {.text section} - `start_r eal_vectors' {.head.text.real_vectors section} make[3]: *** [/home/aik/p/kernels-llvm/llvm/scripts/Makefile.build:388: arch/powerpc/kernel/head_64.o] Error 1 Signed-off-by: Daniel Axtens Signed-off-by: Alexey Kardashevskiy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20211221055904.555763-5-aik@ozlabs.ru

powerpc/64: move interrupt return asm to interrupt_64.S

2021-06-24T14:06:55Z

The next patch would like to move interrupt return assembly code to a low location before general text, so move it into its own file and include via head_64.S Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210617155116.2167984-7-npiggin@gmail.com

powerpc/64s: system call support for scv/rfscv instructions

2020-07-22T13:00:27Z

Add support for the scv instruction on POWER9 and later CPUs. For now this implements the zeroth scv vector 'scv 0', as identical to 'sc' system calls, with the exception that LR is not preserved, nor are volatile CR registers, and error is not indicated with CR0[SO], but by returning a negative errno. rfscv is implemented to return from scv type system calls. It can not be used to return from sc system calls because those are defined to preserve LR. getpid syscall throughput on POWER9 is improved by 26% (428 to 318 cycles), largely due to reducing mtmsr and mtspr. Signed-off-by: Nicholas Piggin [mpe: Fix ppc64e build] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200611081203.995112-3-npiggin@gmail.com

powerpc/64s/exception: move head-64.h exception code to exception-64s.S

2019-08-30T00:32:36Z

The head-64.h code should deal only with the head code sections and offset calculations. No generated code change except BUG line number constants. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20190802105709.27696-19-npiggin@gmail.com

powerpc/64s/exception: move head-64.h code to exception-64s.S where it is used

2019-07-02T10:24:42Z

No generated code change. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman

powerpc/64s/exception: remove STD_EXCEPTION_COMMON variants

2019-07-02T10:24:42Z

These are only called in one place each. No generated code change. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman

powerpc/64s/exception: unwind exception-64s.h macros

2019-07-02T10:24:42Z

Many of these macros just specify 1-4 lines which are only called a few times each at most, and often just once. Remove this indirection. No generated code change. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman

powerpc/64s/exception: Move EXCEPTION_COMMON additions into callers

2019-07-02T10:24:42Z

More cases of code insertion via macros that does not add a great deal. All the additions have to be specified in the macro arguments, so they can just as well go after the macro. No generated code change. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman

powerpc/64s/exception: KVM handler can set the HSRR trap bit

2019-07-02T10:24:42Z

Move the KVM trap HSRR bit into the KVM handler, which can be conditionally applied when hsrr parameter is set. No generated code change. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman

powerpc/64s/exception: merge KVM handler and skip variants

2019-07-02T10:24:42Z

Conditionally expand the skip case if it is specified. No generated code change. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman