| Message ID | 20220515131407.946832-1-xianting.tian@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | RISC-V: Add fast call path of crash_kexec() | expand |
Great Job, I think it's a fixup, we should add Fix: and Cc: stable@kernel.org Reviewed-by: Guo Ren <guoren@kernel.org> On Sun, May 15, 2022 at 9:14 PM Xianting Tian <xianting.tian@linux.alibaba.com> 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/virtio/virtio_mmio.c:806 > 806 *(int *)p = 0xdead; > (gdb) > (gdb) bt > #0 0xffffffe00063a4e0 in test_thread (data=<optimized out>) at drivers/virtio/virtio_mmio.c:806 > #1 0x0000000000000000 in ?? () > > Test code to produce NULL address dereference, > +extern int panic_on_oops; > +static struct task_struct *k; > +static int test_thread(void *data) { > + > + void *p = NULL; > + > + while (!panic_on_oops) > + msleep(2000); > + > + *(int *)p = 0xdead; > + > + return 0; > +} > + > static int __init virtio_mmio_init(void) > { > + k = kthread_run(test_thread, NULL, "test_thread"); > + if (IS_ERR(k)) > + pr_err("Couldn't create test kthread\n"); > + > return platform_driver_register(&virtio_mmio_driver); > } > > Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com> > --- > 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 fe92e119e6a3..e666ebfa2a64 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); > + > bust_spinlocks(0); > add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); > spin_unlock_irq(&die_lock); > -- > 2.17.1 >
just a friendly ping 在 2022/5/15 下午9:14, Xianting Tian 写道: > 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/virtio/virtio_mmio.c:806 > 806 *(int *)p = 0xdead; > (gdb) > (gdb) bt > #0 0xffffffe00063a4e0 in test_thread (data=<optimized out>) at drivers/virtio/virtio_mmio.c:806 > #1 0x0000000000000000 in ?? () > > Test code to produce NULL address dereference, > +extern int panic_on_oops; > +static struct task_struct *k; > +static int test_thread(void *data) { > + > + void *p = NULL; > + > + while (!panic_on_oops) > + msleep(2000); > + > + *(int *)p = 0xdead; > + > + return 0; > +} > + > static int __init virtio_mmio_init(void) > { > + k = kthread_run(test_thread, NULL, "test_thread"); > + if (IS_ERR(k)) > + pr_err("Couldn't create test kthread\n"); > + > return platform_driver_register(&virtio_mmio_driver); > } > > Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com> > --- > 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 fe92e119e6a3..e666ebfa2a64 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); > + > bust_spinlocks(0); > add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); > spin_unlock_irq(&die_lock);
diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c index fe92e119e6a3..e666ebfa2a64 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); + bust_spinlocks(0); add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); spin_unlock_irq(&die_lock);
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/virtio/virtio_mmio.c:806 806 *(int *)p = 0xdead; (gdb) (gdb) bt #0 0xffffffe00063a4e0 in test_thread (data=<optimized out>) at drivers/virtio/virtio_mmio.c:806 #1 0x0000000000000000 in ?? () Test code to produce NULL address dereference, +extern int panic_on_oops; +static struct task_struct *k; +static int test_thread(void *data) { + + void *p = NULL; + + while (!panic_on_oops) + msleep(2000); + + *(int *)p = 0xdead; + + return 0; +} + static int __init virtio_mmio_init(void) { + k = kthread_run(test_thread, NULL, "test_thread"); + if (IS_ERR(k)) + pr_err("Couldn't create test kthread\n"); + return platform_driver_register(&virtio_mmio_driver); } Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com> --- arch/riscv/kernel/traps.c | 4 ++++ 1 file changed, 4 insertions(+)