Messages in this thread | | | Subject | Re: [PATCH v3] RISC-V: Add fixup to support fast call of crash_kexec() | From | Xianting Tian <> | Date | Tue, 7 Jun 2022 09:46:01 +0800 |
| |
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);
| |