Hi Palmer,
The 2 patches are some obviously fixups, could you please have a look?
Recently, I finished the development of Crash-utility for RISCV64,
I will submit the patches soon.
We expect we can normally use Kdump & Crash for 5.19-rcx.
thanks.
Xianting Tian (2):
RISC-V: Fixup fast call of crash_kexec()
RISC-V: use __smp_processor_id() instead of smp_processor_id()
arch/riscv/kernel/machine_kexec.c | 2 +-
arch/riscv/kernel/traps.c | 4 ++++
2 files changed, 5 insertions(+), 1 deletion(-)
--
2.17.1
Use __smp_processor_id() to avoid check the preemption context when
CONFIG_DEBUG_PREEMPT enabled, as we will enter crash kernel and no
return.
Without the patch,
[ 103.781044] sysrq: Trigger a crash
[ 103.784625] Kernel panic - not syncing: sysrq triggered crash
[ 103.837634] CPU1: off
[ 103.889668] CPU2: off
[ 103.933479] CPU3: off
[ 103.939424] Starting crashdump kernel...
[ 103.943442] BUG: using smp_processor_id() in preemptible [00000000] code: sh/346
[ 103.950884] caller is debug_smp_processor_id+0x1c/0x26
[ 103.956051] CPU: 0 PID: 346 Comm: sh Kdump: loaded Not tainted 5.10.113-00002-gce03f03bf4ec-dirty #149
[ 103.965355] Call Trace:
[ 103.967805] [<ffffffe00020372a>] walk_stackframe+0x0/0xa2
[ 103.973206] [<ffffffe000bcf1f4>] show_stack+0x32/0x3e
[ 103.978258] [<ffffffe000bd382a>] dump_stack_lvl+0x72/0x8e
[ 103.983655] [<ffffffe000bd385a>] dump_stack+0x14/0x1c
[ 103.988705] [<ffffffe000bdc8fe>] check_preemption_disabled+0x9e/0xaa
[ 103.995057] [<ffffffe000bdc926>] debug_smp_processor_id+0x1c/0x26
[ 104.001150] [<ffffffe000206c64>] machine_kexec+0x22/0xd0
[ 104.006463] [<ffffffe000291a7e>] __crash_kexec+0x6a/0xa4
[ 104.011774] [<ffffffe000bcf3fa>] panic+0xfc/0x2b0
[ 104.016480] [<ffffffe000656ca4>] sysrq_reset_seq_param_set+0x0/0x70
[ 104.022745] [<ffffffe000657310>] __handle_sysrq+0x8c/0x154
[ 104.028229] [<ffffffe0006577e8>] write_sysrq_trigger+0x5a/0x6a
[ 104.034061] [<ffffffe0003d90e0>] proc_reg_write+0x58/0xd4
[ 104.039459] [<ffffffe00036cff4>] vfs_write+0x7e/0x254
[ 104.044509] [<ffffffe00036d2f6>] ksys_write+0x58/0xbe
[ 104.049558] [<ffffffe00036d36a>] sys_write+0xe/0x16
[ 104.054434] [<ffffffe000201b9a>] ret_from_syscall+0x0/0x2
[ 104.067863] Will call new kernel at ecc00000 from hart id 0
[ 104.074939] FDT image at fc5ee000
[ 104.079523] Bye...
With the patch we can got clear output,
[ 67.740553] sysrq: Trigger a crash
[ 67.744166] Kernel panic - not syncing: sysrq triggered crash
[ 67.809123] CPU1: off
[ 67.865210] CPU2: off
[ 67.909075] CPU3: off
[ 67.919123] Starting crashdump kernel...
[ 67.924900] Will call new kernel at ecc00000 from hart id 0
[ 67.932045] FDT image at fc5ee000
[ 67.935560] Bye...
Fixes: 0e105f1d0037 ("riscv: use hart id instead of cpu id on machine_kexec")
Reviewed-by: Guo Ren <[email protected]>
Signed-off-by: Xianting Tian <[email protected]>
---
arch/riscv/kernel/machine_kexec.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/riscv/kernel/machine_kexec.c b/arch/riscv/kernel/machine_kexec.c
index df8e24559035..86d1b5f9dfb5 100644
--- a/arch/riscv/kernel/machine_kexec.c
+++ b/arch/riscv/kernel/machine_kexec.c
@@ -171,7 +171,7 @@ machine_kexec(struct kimage *image)
struct kimage_arch *internal = &image->arch;
unsigned long jump_addr = (unsigned long) image->start;
unsigned long first_ind_entry = (unsigned long) &image->head;
- unsigned long this_cpu_id = smp_processor_id();
+ unsigned long this_cpu_id = __smp_processor_id();
unsigned long this_hart_id = cpuid_to_hartid_map(this_cpu_id);
unsigned long fdt_addr = internal->fdt_addr;
void *control_code_buffer = page_address(image->control_code_page);
--
2.17.1
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 <[email protected]>
Reviewed-by: Kefeng Wang <[email protected]>
Signed-off-by: Xianting Tian <[email protected]>
---
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);
+
bust_spinlocks(0);
add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
spin_unlock_irq(&die_lock);
--
2.17.1