On 1/19/23 8:44?PM, Luis Claudio R. Goncalves wrote: > On Thu, Jan 19, 2023 at 04:09:44PM -0700, Jens Axboe wrote: >> On 1/19/23 2:03?PM, Salvatore Bonaccorso wrote: >>> Hi Luis, all, >>> >>> On Thu, Jan 19, 2023 at 10:16:34AM -0300, Luis Claudio R. Goncalves wrote: >>>> On Thu, Jan 19, 2023 at 12:38:25PM +0100, Pavel Machek wrote: >>>>> Hi! >>>>> >>>>>>> I'm pleased to announce the 5.10.162-rt78 stable release. >>>>>>> >>>>>>> You can get this release via the git tree at: >>>>>>> >>>>>>> git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-stable-rt.git >>>>>>> >>>>>>> branch: v5.10-rt >>>>>>> Head SHA1: 143ef105f40a65f3ddd57121d4b4bc36eb10cc06 >>>>>>> >>>>>>> Or to build 5.10.162-rt78 directly, the following patches should be applied: >>>>> >>>>>> I see that vanilla 5.10.162-rt78 fails to build with arm64 defconfig. [0] Full log [1] >>>>>> Any pointers on what maybe wrong? >>>>> >>>>> We see the same failure. >>>>> >>>>>> AS arch/arm64/kernel/entry.o >>>>>> arch/arm64/kernel/entry.S: Assembler messages: >>>>>> arch/arm64/kernel/entry.S:763: Error: immediate out of range at operand 3 -- `and x2,x19,#((1<<1)|(1<<0)|(1<<2)|(1<<3)|(1<<4)|(1<<5)|(1<<6)|(1<<13)|(1<<7))' >>>>>> make[2]: *** [scripts/Makefile.build:367: arch/arm64/kernel/entry.o] Error 1 >>>>>> make[1]: *** [scripts/Makefile.build:503: arch/arm64/kernel] Error 2 >>>>>> make: *** [Makefile:1837: arch/arm64] Error 2 >>>>> >>>>> The line is: >>>>> >>>>>> and x2, x19, #_TIF_WORK_MASK >>>> >>>> I believe this is related to the arch/arm64/include/asm/thread_info.h >>>> changes in 5.10.162-rt78, specifically: >>>> >>>> 79a9991e87fe arm64: add support for TIF_NOTIFY_SIGNAL >>>> 1ba44dcf789d Merge tag 'v5.10.162' into v5.10-rt >>>> >>>> The first one is the original change, coming from stable v5.10.162 and the >>>> second one has the merge conflict I fixed in that file due to the existence >>>> of TIF_NEED_RESCHED_LAZY in PREEMPT_RT. >>>> >>>> It escaped me that having TIF_NEED_RESCHED_LAZY set to 13 breaks the AND >>>> statement reported above. Looking at >>>> >>>> b5a5a01d8e9a arm64: uaccess: remove addr_limit_user_check() >>>> >>>> specially this note >>>> >>>> To ensure that _TIF_WORK_MASK can be used as an immediate value in an >>>> AND instruction (as it is in `ret_to_user`), TIF_MTE_ASYNC_FAULT is >>>> renumbered to keep the constituent bits of _TIF_WORK_MASK contiguous. >>>> >>>> I understand that I need to either have to renumber TIF_NEED_RESCHED_LAZY >>>> to 8, with the risk of breaking something else, or backport commit >>>> b5a5a01d8e9a in order to remove TIF_FSCHECK and then safely renumber >>>> TIF_NEED_RESCHED_LAZY. >>>> >>>> Guidance is welcome here :) >>> >>> Should we loop in here Jens, as having some overview of the needed >>> changes for io_uring rebase in the 5.10.y version? (doing so in the >>> mail). >> >> Huh that's funky, I built and (runtime) tested this on arm64 >> specifically. But I do remember some details about the first 8 bits on >> arm, but not arm64. >> >> I guess we need to twiddle that asm to deal with eg 16 bits, rather than >> attempt to backport any TIF removal patches. > > One simple solution, tested with defconfig plus FTRACE options (including > FTRACE_SYSCALLS) enabled, is: > > diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h > index 6eb36a2126e8..37f19bb49d38 100644 > --- a/arch/arm64/include/asm/thread_info.h > +++ b/arch/arm64/include/asm/thread_info.h > @@ -70,12 +70,12 @@ void arch_release_task_struct(struct task_struct *tsk); > #define TIF_FSCHECK 5 /* Check FS is USER_DS on return */ > #define TIF_MTE_ASYNC_FAULT 6 /* MTE Asynchronous Tag Check Fault */ > #define TIF_NOTIFY_SIGNAL 7 /* signal notifications exist */ > -#define TIF_SYSCALL_TRACE 8 /* syscall trace active */ > +#define TIF_NEED_RESCHED_LAZY 8 > #define TIF_SYSCALL_AUDIT 9 /* syscall auditing */ > #define TIF_SYSCALL_TRACEPOINT 10 /* syscall tracepoint for ftrace */ > #define TIF_SECCOMP 11 /* syscall secure computing */ > #define TIF_SYSCALL_EMU 12 /* syscall emulation active */ > -#define TIF_NEED_RESCHED_LAZY 13 > +#define TIF_SYSCALL_TRACE 13 /* syscall trace active */ > #define TIF_MEMDIE 18 /* is terminating due to OOM killer */ > #define TIF_FREEZE 19 > #define TIF_RESTORE_SIGMASK 20 > > Would that be acceptable? With that we ensure the bits in > _TIF_WORK_MASK are contiguous and within the 8 bits limit you > mentioned. And TIF_SYSCALL_TRACE did not seem to have any (build) > problem with the new value. That should work too, the _TIF_WORK_MASK bits being in the lower 8 bits is really all we should care about. I do wonder why I didn't see this in testing - the kernel build bot was also happy with it... But anyway, should be an easy fix. -- Jens Axboe
