Re: [PATCH 2/2] kdump shutdown hook support
From: Michael Ellerman <hidden>
Date: 2007-12-12 23:07:19
On Wed, 2007-12-12 at 16:45 +1100, Michael Neuling wrote:
quoted hunk ↗ jump to hunk
This adds hooks into the default_machine_crash_shutdown so drivers can register a function to be run in the first kernel before we hand off to the second kernel. This should only be used in exceptional circumstances, like where the device can't be reset in the second kernel alone (as is the case with eHEA). To emphasize this, the number of handles allowed to be registered is currently #def to 1. This uses the setjmp/longjmp code to call out to the registered hooks, so any bogus exceptions we encounter will hopefully be recoverable. I've tested with bogus data and instruction exceptions. Signed-off-by: Michael Neuling <redacted> --- arch/powerpc/kernel/crash.c | 90 +++++++++++++++++++++++++++++++++++++++++--- include/asm-powerpc/kexec.h | 3 + 2 files changed, 88 insertions(+), 5 deletions(-) Index: linux-2.6-ozlabs/arch/powerpc/kernel/crash.c ===================================================================--- linux-2.6-ozlabs.orig/arch/powerpc/kernel/crash.c +++ linux-2.6-ozlabs/arch/powerpc/kernel/crash.c@@ -32,6 +32,8 @@ #include <asm/lmb.h> #include <asm/firmware.h> #include <asm/smp.h> +#include <asm/system.h> +#include <asm/setjmp.h> #ifdef DEBUG #include <asm/udbg.h>@@ -45,6 +47,11 @@ int crashing_cpu = -1; static cpumask_t cpus_in_crash = CPU_MASK_NONE; cpumask_t cpus_in_sr = CPU_MASK_NONE; +#define CRASH_SHUTDOWN_HANDLES_NUM 1
CRASH_HANDLER_MAX ?
quoted hunk ↗ jump to hunk
+/* NULL terminated list of shutdown handles */ +static crash_shutdown_t crash_shutdown_handles[CRASH_SHUTDOWN_HANDLES_NUM+1]; +static DEFINE_SPINLOCK(crash_handles_lock); + #ifdef CONFIG_SMP static atomic_t enter_on_soft_reset = ATOMIC_INIT(0);@@ -285,9 +292,69 @@ static inline void crash_kexec_stop_spus } #endif /* CONFIG_SPU_BASE */ +/* + * Register a function to be called on shutdown. Only use this if you + * can't reset your device in the second kernel. + */ +int crash_shutdown_register(crash_shutdown_t handler) +{ + unsigned int i, rc; + + spin_lock(&crash_handles_lock);
+ for(i = 0 ; i <= CRASH_SHUTDOWN_HANDLES_NUM; i++) {
+ if (!crash_shutdown_handles[i]) {
+ /* Insert handle at end */
+ crash_shutdown_handles[i] = handler;
+ rc = 0;
+ break;
+ }
+ }
+ if (i == CRASH_SHUTDOWN_HANDLES_NUM){
+ printk(KERN_ERR "Crash shutdown handles full, "
+ "not registered.\n");
+ rc = 1;
+ }
+
+ spin_unlock(&crash_handles_lock);Perhaps?
+ return rc;
+}
+EXPORT_SYMBOL(crash_shutdown_register);
+
+int crash_shutdown_unregister(crash_shutdown_t handler)
+{
+ unsigned int i;
+
+ spin_lock(&crash_handles_lock);
+ for(i = 0 ; i <= CRASH_SHUTDOWN_HANDLES_NUM; i++)
+ if (crash_shutdown_handles[i] == handler)
+ break;
+
+ if (i == CRASH_SHUTDOWN_HANDLES_NUM){
+ printk(KERN_ERR "Crash shutdown handle not found\n");
+ spin_unlock(&crash_handles_lock);
+ return 1;
+ }
+
+ /* Shift handles down */
+ while(crash_shutdown_handles[i]) {
+ crash_shutdown_handles[i] = crash_shutdown_handles[i+1];
+ i++;
+ }
+ spin_unlock(&crash_handles_lock);
+ return 0;
+}
+EXPORT_SYMBOL(crash_shutdown_unregister);
+
+static long crash_shutdown_buf[SETJMP_BUF_LEN];unsigned long?
quoted hunk ↗ jump to hunk
+ +static int handle_fault(struct pt_regs *regs) +{ + longjmp(crash_shutdown_buf, 1); + return 0; +} + void default_machine_crash_shutdown(struct pt_regs *regs) { - unsigned int irq; + unsigned int i; /* * This function is only called after the system@@ -301,14 +368,27 @@ void default_machine_crash_shutdown(stru */ hard_irq_disable(); - for_each_irq(irq) { - struct irq_desc *desc = irq_desc + irq; + for_each_irq(i) { + struct irq_desc *desc = irq_desc + i; if (desc->status & IRQ_INPROGRESS) - desc->chip->eoi(irq); + desc->chip->eoi(i); if (!(desc->status & IRQ_DISABLED)) - desc->chip->disable(irq); + desc->chip->disable(i); + } + + /* Call registered shutdown routines */ + __debugger_fault_handler = handle_fault; + i = 0; + while(crash_shutdown_handles[i]){ + if (setjmp(crash_shutdown_buf) == 0) { + asm volatile("sync; isync"); + crash_shutdown_handles[i](); + asm volatile("sync; isync"); + __delay(200); + } + i++; }
You should probably reset __debugger_fault_handler, just to be safe. cheers -- Michael Ellerman OzLabs, IBM Australia Development Lab wwweb: http://michael.ellerman.id.au phone: +61 2 6212 1183 (tie line 70 21183) We do not inherit the earth from our ancestors, we borrow it from our children. - S.M.A.R.T Person
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