On Fri, Nov 29, 2024 at 8:55 AM Guo Ren <guoren@xxxxxxxxxx> wrote: > > On Fri, Nov 29, 2024 at 12:19 AM Conor Dooley <conor@xxxxxxxxxx> wrote: > > > > On Thu, Nov 28, 2024 at 03:50:09PM +0100, Alexandre Ghiti wrote: > > > On 28/11/2024 15:14, Conor Dooley wrote: > > > > On Thu, Nov 28, 2024 at 01:41:36PM +0000, Will Deacon wrote: > > > > > On Thu, Nov 28, 2024 at 12:56:55PM +0000, Conor Dooley wrote: > > > > > > On Sun, Nov 03, 2024 at 03:51:53PM +0100, Alexandre Ghiti wrote: > > > > > > > In order to produce a generic kernel, a user can select > > > > > > > CONFIG_COMBO_SPINLOCKS which will fallback at runtime to the ticket > > > > > > > spinlock implementation if Zabha or Ziccrse are not present. > > > > > > > > > > > > > > Note that we can't use alternatives here because the discovery of > > > > > > > extensions is done too late and we need to start with the qspinlock > > > > > > > implementation because the ticket spinlock implementation would pollute > > > > > > > the spinlock value, so let's use static keys. > > > > > > > > > > > > > > This is largely based on Guo's work and Leonardo reviews at [1]. > > > > > > > > > > > > > > Link: https://lore.kernel.org/linux-riscv/20231225125847.2778638-1-guoren@xxxxxxxxxx/ [1] > > > > > > > Signed-off-by: Guo Ren <guoren@xxxxxxxxxx> > > > > > > > Signed-off-by: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx> > > > > > > This patch (now commit ab83647fadae2 ("riscv: Add qspinlock support")) > > > > > > breaks boot on polarfire soc. It dies before outputting anything to the > > > > > > console. My .config has: > > > > > > > > > > > > # CONFIG_RISCV_TICKET_SPINLOCKS is not set > > > > > > # CONFIG_RISCV_QUEUED_SPINLOCKS is not set > > > > > > CONFIG_RISCV_COMBO_SPINLOCKS=y > > > > > I pointed out some of the fragility during review: > > > > > > > > > > https://lore.kernel.org/all/20241111164259.GA20042@willie-the-truck/ > > > > > > > > > > so I'm kinda surprised it got merged tbh :/ > > > > Maybe it could be reverted rather than having a broken boot with the > > > > default settings in -rc1. > > > > > > > > > No need to rush before we know what's happening,I guess you bisected to this > > > commit right? > > > > The symptom is a failure to boot, without any console output, of course > > I bisected it before blaming something specific. But I don't think it is > > "rushing" as having -rc1 broken with an option's default is a massive pain > > in the arse when it comes to testing. > > > > > I don't have this soc, so can you provide $stval/$sepc/$scause, a config, a > > > kernel, anything? > > > > I don't have the former cos it died immediately on boot. config is > > attached. It reproduces in QEMU so you don't need any hardware. > If QEMU could reproduce, could you provide a dmesg by the below method? > > Qemu cmd append: -s -S > ref: https://qemu-project.gitlab.io/qemu/system/gdb.html > > Connect gdb and in console: > 1. file vmlinux > 2. source ./Documentation/admin-guide/kdump/gdbmacros.txt > 3. dmesg > > Then, we could get the kernel's early boot logs from memory. I've reproduced it on qemu, thx for the config. Reading symbols from ../build-rv64lp64/vmlinux... (gdb) tar rem:1234 Remote debugging using :1234 ticket_spin_lock (lock=0xffffffff81b9a5b8 <text_mutex>) at /home/guoren/source/kernel/linux/include/asm-generic/ticket_spinlock.h:49 49 atomic_cond_read_acquire(&lock->val, ticket == (u16)VAL); (gdb) bt #0 ticket_spin_lock (lock=0xffffffff81b9a5b8 <text_mutex>) at /home/guoren/source/kernel/linux/include/asm-generic/ticket_spinlock.h:49 #1 arch_spin_lock (lock=0xffffffff81b9a5b8 <text_mutex>) at /home/guoren/source/kernel/linux/arch/riscv/include/asm/spinlock.h:28 #2 do_raw_spin_lock (lock=lock@entry=0xffffffff81b9a5b8 <text_mutex>) at /home/guoren/source/kernel/linux/kernel/locking/spinlock_debug.c:116 #3 0xffffffff80b2ea0e in __raw_spin_lock_irqsave (lock=0xffffffff81b9a5b8 <text_mutex>) at /home/guoren/source/kernel/linux/include/linux/spinlock_api_smp.h:111 #4 _raw_spin_lock_irqsave (lock=lock@entry=0xffffffff81b9a5b8 <text_mutex>) at /home/guoren/source/kernel/linux/kernel/locking/spinlock.c:162 #5 0xffffffff80b27c54 in rt_mutex_slowtrylock (lock=0xffffffff81b9a5b8 <text_mutex>) at /home/guoren/source/kernel/linux/kernel/locking/rtmutex.c:1393 #6 0xffffffff80b295ea in rt_mutex_try_acquire (lock=0xffffffff81b9a5b8 <text_mutex>) at /home/guoren/source/kernel/linux/kernel/locking/rtmutex.c:319 #7 __rt_mutex_lock (state=2, lock=0xffffffff81b9a5b8 <text_mutex>) at /home/guoren/source/kernel/linux/kernel/locking/rtmutex.c:1805 #8 __mutex_lock_common (ip=18446744071562135170, nest_lock=0x0, subclass=0, state=2, lock=0xffffffff81b9a5b8 <text_mutex>) at /home/guoren/source/kernel/linux/kernel/locking/rtmutex_api.c:518 #9 mutex_lock_nested (lock=0xffffffff81b9a5b8 <text_mutex>, subclass=subclass@entry=0) at /home/guoren/source/kernel/linux/kernel/locking/rtmutex_api.c:529 #10 0xffffffff80010682 in arch_jump_label_transform_queue (entry=entry@entry=0xffffffff8158da28, type=<optimized out>) at /home/guoren/source/kernel/linux/arch/riscv/kernel/jump_label.c:39 #11 0xffffffff801d86b2 in __jump_label_update (key=key@entry=0xffffffff81a1abb0 <qspinlock_key>, entry=0xffffffff8158da28, stop=stop@entry=0xffffffff815a5e68 <__tracepoint_ptr_initcall_finish>, init=init@entry=true) at /home/guoren/source/kernel/linux/kernel/jump_label.c:513 #12 0xffffffff801d890c in jump_label_update (key=key@entry=0xffffffff81a1abb0 <qspinlock_key>) at /home/guoren/source/kernel/linux/kernel/jump_label.c:920 #13 0xffffffff801d8be8 in static_key_disable_cpuslocked (key=key@entry=0xffffffff81a1abb0 <qspinlock_key>) at /home/guoren/source/kernel/linux/kernel/jump_label.c:240 #14 0xffffffff801d8c04 in static_key_disable (key=key@entry=0xffffffff81a1abb0 <qspinlock_key>) at /home/guoren/source/kernel/linux/kernel/jump_label.c:248 #15 0xffffffff80c04a1a in riscv_spinlock_init () at /home/guoren/source/kernel/linux/arch/riscv/kernel/setup.c:271 #16 setup_arch (cmdline_p=cmdline_p@entry=0xffffffff81a03e88) at /home/guoren/source/kernel/linux/arch/riscv/kernel/setup.c:336 #17 0xffffffff80c007a2 in start_kernel () at /home/guoren/source/kernel/linux/init/main.c:922 #18 0xffffffff80001164 in _start_kernel () Backtrace stopped: frame did not save the PC (gdb) p /x lock $1 = 0xffffffff81b9a5b8 (gdb) p /x *lock $2 = {{val = {counter = 0x20000}, {locked = 0x0, pending = 0x0}, {locked_pending = 0x0, tail = 0x2}}} > > > > > > Does the polarfire soc provide Ziccrse? > > > > I don't think that is relevant because ziccrse is not listed in the dts, > > so the kernel should not be assuming that LR/SC has a forward progress > > guarantee. It's not even getting as far as riscv_spinlock_init() given > > several things before that should be emitting logs, so it doesn't even > > get to make any decisions about Ziccrse. > > > > -- > Best Regards > Guo Ren -- Best Regards Guo Ren
