| Message ID | CACRpkdZCiiMTwf7eGJJ9aCKFOC3_xTGv1JKQUijjyp+_++cZ_A@mail.gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [GIT,PULL] Generic entry for ARM | expand |
On Fri, Feb 28 2025 at 13:49, Linus Walleij wrote: > please consider pulling the following git branch for generic entry, > see below. > > This branch was just harvested from my own v5 patch series on > lore with b4 am -t 20250225-arm-generic-entry-v5-0-2f02313653e5@linaro.org > then git am on top of v6.14-rc1, so you can do the same if you > prefer. > > It's possible to squash patches, even all of them into one > big all-or-nothing patch, given the not very gradual nature generic > entry conversion seems to have. > > Main upsides and downsides are in the signed tag. > > I don't know who the most important stakeholders are, but I guess > the context tracker maintainer (Paul McKenney) and the people working > on generic entry (tglx) could have a say on how important this is, or isn't. > > I think it's pretty neat. It's valuable to consolidate these common functionalities across architectures as it reduces maintainence costs. I read through the patches and did not find anything offending there. Thanks for doing that! Acked-by: Thomas Gleixner <tglx@linutronix.de>
On Fri, Feb 28, 2025 at 01:49:36PM +0100, Linus Walleij wrote: > Hi Russell, > > please consider pulling the following git branch for generic entry, > see below. > > This branch was just harvested from my own v5 patch series on > lore with b4 am -t 20250225-arm-generic-entry-v5-0-2f02313653e5@linaro.org > then git am on top of v6.14-rc1, so you can do the same if you > prefer. > > It's possible to squash patches, even all of them into one > big all-or-nothing patch, given the not very gradual nature generic > entry conversion seems to have. > > Main upsides and downsides are in the signed tag. > > I don't know who the most important stakeholders are, but I guess > the context tracker maintainer (Paul McKenney) and the people working > on generic entry (tglx) could have a say on how important this is, or isn't. > > I think it's pretty neat. No argument here! Once you are confident that you have all the needed "noinstr" and "__always_inline" instances in place, could you please add ARCH_WANTS_NO_INSTR to the list of "select" clauses for "config ARM" in arch/arm/Kconfig? Once all architectures that support trampoline-based tracing also select ARCH_WANTS_NO_INSTR we can drop RCU Tasks Rude. ;-) In the meantime, for the series: Acked-by: Paul E. McKenney <paulmck@kernel.org> Thanx, Paul > Yours, > Linus Walleij > > The following changes since commit 2014c95afecee3e76ca4a56956a936e23283f05b: > > Linux 6.14-rc1 (2025-02-02 15:39:26 -0800) > > are available in the Git repository at: > > git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-integrator.git > tags/arm-generic-entry-for-v6.15 > > for you to fetch changes up to 98b8e133458a3feefdf882ea16fb7f1f576a49e5: > > ARM: entry: Reimplement local restart in C (2025-02-28 13:40:44 +0100) > > ---------------------------------------------------------------- > Main upsides: > > - Using the same common entry as used by x86_64, RISCV, S390 > and Loongarch, probably soon also ARM64. > > - Moves ARM away from the obsoleted context tracker entry points > user_enter_callable() and user_exit_callable() are now only used > by ARM, CSKY and Xtensa. > > - Solves a few lockdep warnings in the process. > > - Converts a bit of assembly into C. > > Main downside: > > - Slightly increased system call overhead, around 6% in > measurements. > > ---------------------------------------------------------------- > Linus Walleij (31): > ARM: Prepare includes for generic entry > ARM: ptrace: Split report_syscall() > ARM: entry: Skip ret_slow_syscall label > ARM: process: Rewrite ret_from_fork i C > ARM: process: Remove local restart > ARM: entry: Invoke syscalls using C > ARM: entry: Rewrite two asm calls in C > ARM: entry: Move trace entry to C function > ARM: entry: save the syscall sp in thread_info > ARM: entry: move all tracing invocation to C > ARM: entry: Merge the common and trace entry code > ARM: entry: Rename syscall invocation > ARM: entry: Create user_mode_enter/exit > ARM: entry: Drop trace argument from usr_entry macro > ARM: entry: Separate call path for syscall SWI entry > ARM: entry: Drop argument to asm_irqentry macros > ARM: entry: Implement syscall_exit_to_user_mode() > ARM: entry: Drop the superfast ret_fast_syscall > ARM: entry: Remove fast and offset register restore > ARM: entry: Untangle ret_fast_syscall/to_user > ARM: entry: Do not double-call exit functions > ARM: entry: Move work processing to C > ARM: entry: Stop exiting syscalls like IRQs > ARM: entry: Complete syscall and IRQ transition to C > ARM: entry: Create irqentry calls from kernel mode > ARM: entry: Move in-kernel hardirq tracing to C > ARM: irq: Add irqstack helper > ARM: entry: Convert to generic entry > ARM: entry: Handle dabt, pabt, and und as interrupts > ARM: entry: Block IRQs in early IRQ context > ARM: entry: Reimplement local restart in C > > arch/arm/Kconfig | 1 + > arch/arm/include/asm/entry-common.h | 66 ++++++++++++ > arch/arm/include/asm/entry.h | 14 +++ > arch/arm/include/asm/ptrace.h | 8 +- > arch/arm/include/asm/signal.h | 4 - > arch/arm/include/asm/stacktrace.h | 2 +- > arch/arm/include/asm/switch_to.h | 4 + > arch/arm/include/asm/syscall.h | 7 ++ > arch/arm/include/asm/thread_info.h | 22 ++-- > arch/arm/include/asm/traps.h | 5 +- > arch/arm/include/uapi/asm/ptrace.h | 2 + > arch/arm/kernel/Makefile | 5 +- > arch/arm/kernel/asm-offsets.c | 1 + > arch/arm/kernel/entry-armv.S | 82 ++++----------- > arch/arm/kernel/entry-common.S | 198 +++++++++++++----------------------- > arch/arm/kernel/entry-header.S | 100 ++---------------- > arch/arm/kernel/entry.c | 120 ++++++++++++++++++++++ > arch/arm/kernel/irq.c | 6 ++ > arch/arm/kernel/irq.h | 2 + > arch/arm/kernel/process.c | 25 ++++- > arch/arm/kernel/ptrace.c | 81 +-------------- > arch/arm/kernel/signal.c | 68 +++---------- > arch/arm/kernel/syscall.c | 59 +++++++++++ > arch/arm/kernel/traps.c | 30 +----- > arch/arm/mm/abort-ev4.S | 2 +- > arch/arm/mm/abort-ev4t.S | 2 +- > arch/arm/mm/abort-ev5t.S | 4 +- > arch/arm/mm/abort-ev5tj.S | 6 +- > arch/arm/mm/abort-ev6.S | 2 +- > arch/arm/mm/abort-ev7.S | 2 +- > arch/arm/mm/abort-lv4t.S | 36 +++---- > arch/arm/mm/abort-macro.S | 2 +- > arch/arm/mm/abort-nommu.S | 2 +- > arch/arm/mm/fault.c | 4 +- > arch/arm/mm/fault.h | 8 +- > arch/arm/mm/pabort-legacy.S | 2 +- > arch/arm/mm/pabort-v6.S | 2 +- > arch/arm/mm/pabort-v7.S | 2 +- > 38 files changed, 484 insertions(+), 504 deletions(-) > create mode 100644 arch/arm/include/asm/entry-common.h > create mode 100644 arch/arm/include/asm/entry.h > create mode 100644 arch/arm/kernel/entry.c > create mode 100644 arch/arm/kernel/irq.h > create mode 100644 arch/arm/kernel/syscall.c
On Wed, Mar 12, 2025 at 7:00 PM Paul E. McKenney <paulmck@kernel.org> wrote: > Once you are confident that you have all the needed "noinstr" > and "__always_inline" instances in place, could you please add > ARCH_WANTS_NO_INSTR to the list of "select" clauses for "config ARM" > in arch/arm/Kconfig? I would love to do that, I'm just not sure what this really entails. Surely this patchset tags a noinstr on every entry point from exceptions and syscall software interrupts. Documentation/core-api/entry.rst is pretty good at explaining this. But what makes me uncertain are things that are tagged "notrace", such as void notrace cpu_init(void) - surely we don't trace, but should that be "noinstr"? It's even marked "notrace" but not "noinstr" in arm64. cpu_init() is called from e.g.: asmlinkage void secondary_start_kernel(struct task_struct *task) OK should this also be noinstr? Or is that just implied because of asmlinkage? <linux/compiler_types.h> will resolve to: #if defined(CC_USING_HOTPATCH) #define notrace __attribute__((hotpatch(0, 0))) #elif defined(CC_USING_PATCHABLE_FUNCTION_ENTRY) #define notrace __attribute__((patchable_function_entry(0, 0))) #else #define notrace __attribute__((__no_instrument_function__)) #endif which I read as three different ways of saying "don't patch here". Which is confusingly similar or identical to what noinstr does, I do see that noinstr pushes the code to separate section but that in turn might be what __attribute__((__no_instrument_function__)) and friends does? Are they equivalent? sched_clock_noinstr() is tagged noinstr and sched_clock() is tagged notrace, so there must be a difference here. secondary_start_kernel() is tagged "notrace" on arm64 but not on arm, should it be tagged "noinstr" or "notrace"? This kind of stuff makes me uncertain about how this is to be done. A "noinstr vs notrace" section in Documentation/core-api/entry.rst would help a lot I think! Yours, Linus Walleij
Hi Russell, please consider pulling the following git branch for generic entry, see below. This branch was just harvested from my own v5 patch series on lore with b4 am -t 20250225-arm-generic-entry-v5-0-2f02313653e5@linaro.org then git am on top of v6.14-rc1, so you can do the same if you prefer. It's possible to squash patches, even all of them into one big all-or-nothing patch, given the not very gradual nature generic entry conversion seems to have. Main upsides and downsides are in the signed tag. I don't know who the most important stakeholders are, but I guess the context tracker maintainer (Paul McKenney) and the people working on generic entry (tglx) could have a say on how important this is, or isn't. I think it's pretty neat. Yours, Linus Walleij The following changes since commit 2014c95afecee3e76ca4a56956a936e23283f05b: Linux 6.14-rc1 (2025-02-02 15:39:26 -0800) are available in the Git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-integrator.git tags/arm-generic-entry-for-v6.15 for you to fetch changes up to 98b8e133458a3feefdf882ea16fb7f1f576a49e5: ARM: entry: Reimplement local restart in C (2025-02-28 13:40:44 +0100) ---------------------------------------------------------------- Main upsides: - Using the same common entry as used by x86_64, RISCV, S390 and Loongarch, probably soon also ARM64. - Moves ARM away from the obsoleted context tracker entry points user_enter_callable() and user_exit_callable() are now only used by ARM, CSKY and Xtensa. - Solves a few lockdep warnings in the process. - Converts a bit of assembly into C. Main downside: - Slightly increased system call overhead, around 6% in measurements. ---------------------------------------------------------------- Linus Walleij (31): ARM: Prepare includes for generic entry ARM: ptrace: Split report_syscall() ARM: entry: Skip ret_slow_syscall label ARM: process: Rewrite ret_from_fork i C ARM: process: Remove local restart ARM: entry: Invoke syscalls using C ARM: entry: Rewrite two asm calls in C ARM: entry: Move trace entry to C function ARM: entry: save the syscall sp in thread_info ARM: entry: move all tracing invocation to C ARM: entry: Merge the common and trace entry code ARM: entry: Rename syscall invocation ARM: entry: Create user_mode_enter/exit ARM: entry: Drop trace argument from usr_entry macro ARM: entry: Separate call path for syscall SWI entry ARM: entry: Drop argument to asm_irqentry macros ARM: entry: Implement syscall_exit_to_user_mode() ARM: entry: Drop the superfast ret_fast_syscall ARM: entry: Remove fast and offset register restore ARM: entry: Untangle ret_fast_syscall/to_user ARM: entry: Do not double-call exit functions ARM: entry: Move work processing to C ARM: entry: Stop exiting syscalls like IRQs ARM: entry: Complete syscall and IRQ transition to C ARM: entry: Create irqentry calls from kernel mode ARM: entry: Move in-kernel hardirq tracing to C ARM: irq: Add irqstack helper ARM: entry: Convert to generic entry ARM: entry: Handle dabt, pabt, and und as interrupts ARM: entry: Block IRQs in early IRQ context ARM: entry: Reimplement local restart in C arch/arm/Kconfig | 1 + arch/arm/include/asm/entry-common.h | 66 ++++++++++++ arch/arm/include/asm/entry.h | 14 +++ arch/arm/include/asm/ptrace.h | 8 +- arch/arm/include/asm/signal.h | 4 - arch/arm/include/asm/stacktrace.h | 2 +- arch/arm/include/asm/switch_to.h | 4 + arch/arm/include/asm/syscall.h | 7 ++ arch/arm/include/asm/thread_info.h | 22 ++-- arch/arm/include/asm/traps.h | 5 +- arch/arm/include/uapi/asm/ptrace.h | 2 + arch/arm/kernel/Makefile | 5 +- arch/arm/kernel/asm-offsets.c | 1 + arch/arm/kernel/entry-armv.S | 82 ++++----------- arch/arm/kernel/entry-common.S | 198 +++++++++++++----------------------- arch/arm/kernel/entry-header.S | 100 ++---------------- arch/arm/kernel/entry.c | 120 ++++++++++++++++++++++ arch/arm/kernel/irq.c | 6 ++ arch/arm/kernel/irq.h | 2 + arch/arm/kernel/process.c | 25 ++++- arch/arm/kernel/ptrace.c | 81 +-------------- arch/arm/kernel/signal.c | 68 +++---------- arch/arm/kernel/syscall.c | 59 +++++++++++ arch/arm/kernel/traps.c | 30 +----- arch/arm/mm/abort-ev4.S | 2 +- arch/arm/mm/abort-ev4t.S | 2 +- arch/arm/mm/abort-ev5t.S | 4 +- arch/arm/mm/abort-ev5tj.S | 6 +- arch/arm/mm/abort-ev6.S | 2 +- arch/arm/mm/abort-ev7.S | 2 +- arch/arm/mm/abort-lv4t.S | 36 +++---- arch/arm/mm/abort-macro.S | 2 +- arch/arm/mm/abort-nommu.S | 2 +- arch/arm/mm/fault.c | 4 +- arch/arm/mm/fault.h | 8 +- arch/arm/mm/pabort-legacy.S | 2 +- arch/arm/mm/pabort-v6.S | 2 +- arch/arm/mm/pabort-v7.S | 2 +- 38 files changed, 484 insertions(+), 504 deletions(-) create mode 100644 arch/arm/include/asm/entry-common.h create mode 100644 arch/arm/include/asm/entry.h create mode 100644 arch/arm/kernel/entry.c create mode 100644 arch/arm/kernel/irq.h create mode 100644 arch/arm/kernel/syscall.c