Interrupts are blocked in SDEI context, per the SDEI spec: "The client
interrupts cannot preempt the event handler." If we crashed in the SDEI
handler-running context (as with ACPI's AGDI) then we need to clean up the
SDEI state before proceeding to the crash kernel so that the crash kernel
can have working interrupts.
Track the active SDEI handler per-cpu so that we can COMPLETE_AND_RESUME
the handler, discarding the interrupted context.
Fixes: f5df26961853 ("arm64: kernel: Add arch-specific SDEI entry code and CPU masking")
Signed-off-by: D Scott Phillips <[email protected]>
Reviewed-by: James Morse <[email protected]>
Cc: [email protected]
---
Changes since v3:
- Fixed messed up #ifdef logic in entry.S
- Moved sdei_handler_abort() logic from smp.c to sdei.c
v3 Link: https://lore.kernel.org/linux-arm-kernel/[email protected]/
Changes since v2:
- Dropped the patch fiddling with the sdei conduit.
v2 Link: https://lore.kernel.org/linux-arm-kernel/[email protected]/
Changes since v1:
- Store the active SDEI event being handled per-cpu, use the per-cpu active
handler information to know when to abort.
- Add prints before attempting to abort sdei handlers.
v1 Link: https://lore.kernel.org/linux-arm-kernel/[email protected]/
arch/arm64/include/asm/sdei.h | 11 +++++++++++
arch/arm64/kernel/entry.S | 27 +++++++++++++++++++++++++--
arch/arm64/kernel/sdei.c | 22 ++++++++++++++++++++++
arch/arm64/kernel/smp.c | 8 ++++----
4 files changed, 62 insertions(+), 6 deletions(-)
diff --git a/arch/arm64/include/asm/sdei.h b/arch/arm64/include/asm/sdei.h
index 4292d9bafb9d..98786108c493 100644
--- a/arch/arm64/include/asm/sdei.h
+++ b/arch/arm64/include/asm/sdei.h
@@ -17,6 +17,9 @@
#include <asm/virt.h>
+DECLARE_PER_CPU(struct sdei_registered_event *, sdei_active_normal_event);
+DECLARE_PER_CPU(struct sdei_registered_event *, sdei_active_critical_event);
+
extern unsigned long sdei_exit_mode;
/* Software Delegated Exception entry point from firmware*/
@@ -29,6 +32,14 @@ asmlinkage void __sdei_asm_entry_trampoline(unsigned long event_num,
unsigned long pc,
unsigned long pstate);
+#ifdef CONFIG_ARM_SDE_INTERFACE
+/* Abort a running handler. Context is discarded. */
+void sdei_handler_abort(void);
+void __sdei_handler_abort(void);
+#else
+static inline void sdei_handler_abort(void) { }
+#endif
+
/*
* The above entry point does the minimum to call C code. This function does
* anything else, before calling the driver.
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index ab2a6e33c052..1b4a65a33186 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -1003,9 +1003,13 @@ SYM_CODE_START(__sdei_asm_handler)
mov x19, x1
-#if defined(CONFIG_VMAP_STACK) || defined(CONFIG_SHADOW_CALL_STACK)
+ /* Store the registered-event for crash_smp_send_stop() */
ldrb w4, [x19, #SDEI_EVENT_PRIORITY]
-#endif
+ cbnz w4, 1f
+ adr_this_cpu dst=x5, sym=sdei_active_normal_event, tmp=x6
+ b 2f
+1: adr_this_cpu dst=x5, sym=sdei_active_critical_event, tmp=x6
+2: str x19, [x5]
#ifdef CONFIG_VMAP_STACK
/*
@@ -1072,6 +1076,14 @@ SYM_CODE_START(__sdei_asm_handler)
ldr_l x2, sdei_exit_mode
+ /* Clear the registered-event seen by crash_smp_send_stop() */
+ ldrb w3, [x4, #SDEI_EVENT_PRIORITY]
+ cbnz w3, 1f
+ adr_this_cpu dst=x5, sym=sdei_active_normal_event, tmp=x6
+ b 2f
+1: adr_this_cpu dst=x5, sym=sdei_active_critical_event, tmp=x6
+2: str xzr, [x5]
+
alternative_if_not ARM64_UNMAP_KERNEL_AT_EL0
sdei_handler_exit exit_mode=x2
alternative_else_nop_endif
@@ -1082,4 +1094,15 @@ alternative_else_nop_endif
#endif
SYM_CODE_END(__sdei_asm_handler)
NOKPROBE(__sdei_asm_handler)
+
+SYM_CODE_START(__sdei_handler_abort)
+ mov_q x0, SDEI_1_0_FN_SDEI_EVENT_COMPLETE_AND_RESUME
+ adr x1, 1f
+ ldr_l x2, sdei_exit_mode
+ sdei_handler_exit exit_mode=x2
+ // exit the handler and jump to the next instruction.
+ // Exit will stomp x0-x17, PSTATE, ELR_ELx, and SPSR_ELx.
+1: ret
+SYM_CODE_END(__sdei_handler_abort)
+NOKPROBE(__sdei_handler_abort)
#endif /* CONFIG_ARM_SDE_INTERFACE */
diff --git a/arch/arm64/kernel/sdei.c b/arch/arm64/kernel/sdei.c
index 830be01af32d..fcd418af386e 100644
--- a/arch/arm64/kernel/sdei.c
+++ b/arch/arm64/kernel/sdei.c
@@ -47,6 +47,9 @@ DEFINE_PER_CPU(unsigned long *, sdei_shadow_call_stack_normal_ptr);
DEFINE_PER_CPU(unsigned long *, sdei_shadow_call_stack_critical_ptr);
#endif
+DEFINE_PER_CPU(struct sdei_registered_event *, sdei_active_normal_event);
+DEFINE_PER_CPU(struct sdei_registered_event *, sdei_active_critical_event);
+
static void _free_sdei_stack(unsigned long * __percpu *ptr, int cpu)
{
unsigned long *p;
@@ -262,3 +265,22 @@ unsigned long __kprobes do_sdei_event(struct pt_regs *regs,
return vbar + 0x480;
}
+
+void sdei_handler_abort(void)
+{
+ /*
+ * If the crash happened in an SDEI event handler then we need to
+ * finish the handler with the firmware so that we can have working
+ * interrupts in the crash kernel.
+ */
+ if (__this_cpu_read(sdei_active_critical_event)) {
+ pr_warn("SDEI: still in SDEI critical event context, attempting to finish handler.\n");
+ __sdei_handler_abort();
+ __this_cpu_write(sdei_active_critical_event, NULL);
+ }
+ if (__this_cpu_read(sdei_active_normal_event)) {
+ pr_warn("SDEI: still in SDEI normal event context, attempting to finish handler.\n");
+ __sdei_handler_abort();
+ __this_cpu_write(sdei_active_normal_event, NULL);
+ }
+}
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index d00d4cbb31b1..c6b882e589e6 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -1048,10 +1048,8 @@ void crash_smp_send_stop(void)
* If this cpu is the only one alive at this point in time, online or
* not, there are no stop messages to be sent around, so just back out.
*/
- if (num_other_online_cpus() == 0) {
- sdei_mask_local_cpu();
- return;
- }
+ if (num_other_online_cpus() == 0)
+ goto skip_ipi;
cpumask_copy(&mask, cpu_online_mask);
cpumask_clear_cpu(smp_processor_id(), &mask);
@@ -1070,7 +1068,9 @@ void crash_smp_send_stop(void)
pr_warn("SMP: failed to stop secondary CPUs %*pbl\n",
cpumask_pr_args(&mask));
+skip_ipi:
sdei_mask_local_cpu();
+ sdei_handler_abort();
}
bool smp_crash_stop_failed(void)
--
2.41.0
Hi Scott,
kernel test robot noticed the following build errors:
[auto build test ERROR on arm64/for-next/core]
[also build test ERROR on arm/for-next arm/fixes kvmarm/next soc/for-next linus/master v6.4 next-20230623]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/D-Scott-Phillips/arm64-sdei-abort-running-SDEI-handlers-during-crash/20230626-074210
base: https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core
patch link: https://lore.kernel.org/r/20230625234033.672594-1-scott%40os.amperecomputing.com
patch subject: [PATCH v4] arm64: sdei: abort running SDEI handlers during crash
config: arm64-defconfig (https://download.01.org/0day-ci/archive/20230626/[email protected]/config)
compiler: aarch64-linux-gcc (GCC) 12.3.0
reproduce: (https://download.01.org/0day-ci/archive/20230626/[email protected]/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
All errors (new ones prefixed by >>):
arch/arm64/kernel/smp.c: In function 'crash_smp_send_stop':
>> arch/arm64/kernel/smp.c:1073:9: error: implicit declaration of function 'sdei_handler_abort'; did you mean 'acpi_handle_alert'? [-Werror=implicit-function-declaration]
1073 | sdei_handler_abort();
| ^~~~~~~~~~~~~~~~~~
| acpi_handle_alert
cc1: some warnings being treated as errors
vim +1073 arch/arm64/kernel/smp.c
1030
1031 #ifdef CONFIG_KEXEC_CORE
1032 void crash_smp_send_stop(void)
1033 {
1034 static int cpus_stopped;
1035 cpumask_t mask;
1036 unsigned long timeout;
1037
1038 /*
1039 * This function can be called twice in panic path, but obviously
1040 * we execute this only once.
1041 */
1042 if (cpus_stopped)
1043 return;
1044
1045 cpus_stopped = 1;
1046
1047 /*
1048 * If this cpu is the only one alive at this point in time, online or
1049 * not, there are no stop messages to be sent around, so just back out.
1050 */
1051 if (num_other_online_cpus() == 0)
1052 goto skip_ipi;
1053
1054 cpumask_copy(&mask, cpu_online_mask);
1055 cpumask_clear_cpu(smp_processor_id(), &mask);
1056
1057 atomic_set(&waiting_for_crash_ipi, num_other_online_cpus());
1058
1059 pr_crit("SMP: stopping secondary CPUs\n");
1060 smp_cross_call(&mask, IPI_CPU_CRASH_STOP);
1061
1062 /* Wait up to one second for other CPUs to stop */
1063 timeout = USEC_PER_SEC;
1064 while ((atomic_read(&waiting_for_crash_ipi) > 0) && timeout--)
1065 udelay(1);
1066
1067 if (atomic_read(&waiting_for_crash_ipi) > 0)
1068 pr_warn("SMP: failed to stop secondary CPUs %*pbl\n",
1069 cpumask_pr_args(&mask));
1070
1071 skip_ipi:
1072 sdei_mask_local_cpu();
> 1073 sdei_handler_abort();
1074 }
1075
--
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https://github.com/intel/lkp-tests/wiki