Messages in this thread | | | Date | Tue, 7 Jun 2022 09:21:44 +0800 | Subject | Re: [PATCH v3] RISC-V: Add fixup to support fast call of crash_kexec() | From | Kefeng Wang <> |
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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,
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> bust_spinlocks(0); > add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); > spin_unlock_irq(&die_lock);
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