| Message ID | 20220606123750.2884245-1-xianting.tian@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3] RISC-V: Add fixup to support fast call of crash_kexec() | expand |
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);
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);
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);
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);
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); + 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/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(+)