Messages in this thread | | | Subject | Re: [PATCH v3] RISC-V: Add fixup to support fast call of crash_kexec() | From | Xianting Tian <> | Date | Fri, 17 Jun 2022 14:40:44 +0800 |
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Hi Palmer
Will you apply this patch for 5.19?
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);
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