Messages in this thread | | | From | Guo Ren <> | Date | Fri, 17 Jun 2022 15:13:34 +0800 | Subject | Re: [PATCH v3] RISC-V: Add fixup to support fast call of crash_kexec() |
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Hi Xianting,
On Fri, Jun 17, 2022 at 2:40 PM Xianting Tian <xianting.tian@linux.alibaba.com> wrote: > > Hi Palmer > > Will you apply this patch for 5.19? Maybe we could update tile with [PATCH v3] RISC-V: Fixup fast call of crash_kexec() for a V4.
It's a fixup not feature, that would mislead maintainer. And add "Reviewed-by: Kefeng Wang".
> > thanks > > 在 2022/6/7 上午9:46, Xianting Tian 写道: > > > > 在 2022/6/7 上午9:21, Kefeng Wang 写道: > >> > >> On 2022/6/6 20:37, Xianting Tian wrote: > >>> Currently, almost all archs (x86, arm64, mips...) support fast call > >>> of crash_kexec() when "regs && kexec_should_crash()" is true. But > >>> RISC-V not, it can only enter crash system via panic(). However panic() > >>> doesn't pass the regs of the real accident scene to crash_kexec(), > >>> it caused we can't get accurate backtrace via gdb, > >>> $ riscv64-linux-gnu-gdb vmlinux vmcore > >>> Reading symbols from vmlinux... > >>> [New LWP 95] > >>> #0 console_unlock () at kernel/printk/printk.c:2557 > >>> 2557 if (do_cond_resched) > >>> (gdb) bt > >>> #0 console_unlock () at kernel/printk/printk.c:2557 > >>> #1 0x0000000000000000 in ?? () > >>> > >>> With the patch we can get the accurate backtrace, > >>> $ riscv64-linux-gnu-gdb vmlinux vmcore > >>> Reading symbols from vmlinux... > >>> [New LWP 95] > >>> #0 0xffffffe00063a4e0 in test_thread (data=<optimized out>) at > >>> drivers/test_crash.c:81 > >>> 81 *(int *)p = 0xdead; > >>> (gdb) > >>> (gdb) bt > >>> #0 0xffffffe00064d5c0 in test_thread (data=<optimized out>) at > >>> drivers/test_crash.c:81 > >>> #1 0x0000000000000000 in ?? () > >>> > >>> Test code to produce NULL address dereference in test_crash.c, > >>> void *p = NULL; > >>> *(int *)p = 0xdead; > >>> > >>> Fixes: 76d2a0493a17 ("RISC-V: Init and Halt Code") > >>> Reviewed-by: Guo Ren <guoren@kernel.org> > >>> Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com> > >>> --- > >>> Changes from v1: > >>> - simplify the commit message > >>> Changes from v2: > >>> - add fixup in title > >>> --- > >>> arch/riscv/kernel/traps.c | 4 ++++ > >>> 1 file changed, 4 insertions(+) > >>> > >>> diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c > >>> index b40426509244..39d0f8bba4b4 100644 > >>> --- a/arch/riscv/kernel/traps.c > >>> +++ b/arch/riscv/kernel/traps.c > >>> @@ -16,6 +16,7 @@ > >>> #include <linux/mm.h> > >>> #include <linux/module.h> > >>> #include <linux/irq.h> > >>> +#include <linux/kexec.h> > >>> #include <asm/asm-prototypes.h> > >>> #include <asm/bug.h> > >>> @@ -44,6 +45,9 @@ void die(struct pt_regs *regs, const char *str) > >>> ret = notify_die(DIE_OOPS, str, regs, 0, regs->cause, SIGSEGV); > >>> + if (regs && kexec_should_crash(current)) > >>> + crash_kexec(regs); > >>> + > >> > >> It seems that the regs won't be null, right? except that, > > > > Autually both regs won't be null, But if it is triggered by panic() , > > the regs are got via riscv_crash_save_regs(), which are the regs of > > that moment, but not the real accident scene. > > > >> > >> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> > >> > >>> bust_spinlocks(0); > >>> add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); > >>> spin_unlock_irq(&die_lock);
-- Best Regards Guo Ren
ML: https://lore.kernel.org/linux-csky/
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