![Haren Myneni](/assets/img/avatar_default.png)
- This contains the arch specific changes for the following the kdump generic fixes which were already accepted in the upstream. . Capturing CPU registers (for the case of 'panic' and invoking the dump using 'sysrq-trigger') from a function (stack frame) which will be not be available during the kdump boot. Hence, might result in invalid stack trace. . Dynamically allocating per cpu ELF notes section instead of statically for NR_CPUS. - Fix the compiler warning in prom_init.c. Signed-off-by: Haren Myneni <haren@us.ibm.com> Signed-off-by: Paul Mackerras <paulus@samba.org>
198 lines
4.6 KiB
C
198 lines
4.6 KiB
C
/*
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* Architecture specific (PPC64) functions for kexec based crash dumps.
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*
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* Copyright (C) 2005, IBM Corp.
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*
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* Created by: Haren Myneni
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*
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* This source code is licensed under the GNU General Public License,
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* Version 2. See the file COPYING for more details.
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*
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*/
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#undef DEBUG
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#include <linux/kernel.h>
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#include <linux/smp.h>
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#include <linux/reboot.h>
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#include <linux/kexec.h>
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#include <linux/bootmem.h>
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#include <linux/crash_dump.h>
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#include <linux/delay.h>
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#include <linux/elf.h>
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#include <linux/elfcore.h>
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#include <linux/init.h>
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#include <linux/types.h>
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#include <asm/processor.h>
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#include <asm/machdep.h>
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#include <asm/kdump.h>
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#include <asm/lmb.h>
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#include <asm/firmware.h>
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#include <asm/smp.h>
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#ifdef DEBUG
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#include <asm/udbg.h>
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#define DBG(fmt...) udbg_printf(fmt)
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#else
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#define DBG(fmt...)
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#endif
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/* This keeps a track of which one is crashing cpu. */
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int crashing_cpu = -1;
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static u32 *append_elf_note(u32 *buf, char *name, unsigned type, void *data,
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size_t data_len)
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{
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struct elf_note note;
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note.n_namesz = strlen(name) + 1;
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note.n_descsz = data_len;
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note.n_type = type;
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memcpy(buf, ¬e, sizeof(note));
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buf += (sizeof(note) +3)/4;
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memcpy(buf, name, note.n_namesz);
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buf += (note.n_namesz + 3)/4;
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memcpy(buf, data, note.n_descsz);
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buf += (note.n_descsz + 3)/4;
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return buf;
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}
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static void final_note(u32 *buf)
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{
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struct elf_note note;
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note.n_namesz = 0;
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note.n_descsz = 0;
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note.n_type = 0;
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memcpy(buf, ¬e, sizeof(note));
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}
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static void crash_save_this_cpu(struct pt_regs *regs, int cpu)
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{
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struct elf_prstatus prstatus;
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u32 *buf;
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if ((cpu < 0) || (cpu >= NR_CPUS))
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return;
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/* Using ELF notes here is opportunistic.
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* I need a well defined structure format
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* for the data I pass, and I need tags
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* on the data to indicate what information I have
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* squirrelled away. ELF notes happen to provide
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* all of that that no need to invent something new.
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*/
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buf = (u32*)per_cpu_ptr(crash_notes, cpu);
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if (!buf)
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return;
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memset(&prstatus, 0, sizeof(prstatus));
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prstatus.pr_pid = current->pid;
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elf_core_copy_regs(&prstatus.pr_reg, regs);
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buf = append_elf_note(buf, "CORE", NT_PRSTATUS, &prstatus,
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sizeof(prstatus));
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final_note(buf);
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}
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#ifdef CONFIG_SMP
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static atomic_t waiting_for_crash_ipi;
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void crash_ipi_callback(struct pt_regs *regs)
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{
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int cpu = smp_processor_id();
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if (cpu == crashing_cpu)
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return;
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if (!cpu_online(cpu))
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return;
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if (ppc_md.kexec_cpu_down)
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ppc_md.kexec_cpu_down(1, 1);
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local_irq_disable();
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crash_save_this_cpu(regs, cpu);
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atomic_dec(&waiting_for_crash_ipi);
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kexec_smp_wait();
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/* NOTREACHED */
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}
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static void crash_kexec_prepare_cpus(void)
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{
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unsigned int msecs;
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atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
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crash_send_ipi(crash_ipi_callback);
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smp_wmb();
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/*
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* FIXME: Until we will have the way to stop other CPUSs reliabally,
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* the crash CPU will send an IPI and wait for other CPUs to
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* respond. If not, proceed the kexec boot even though we failed to
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* capture other CPU states.
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*/
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msecs = 1000000;
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while ((atomic_read(&waiting_for_crash_ipi) > 0) && (--msecs > 0)) {
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barrier();
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mdelay(1);
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}
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/* Would it be better to replace the trap vector here? */
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/*
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* FIXME: In case if we do not get all CPUs, one possibility: ask the
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* user to do soft reset such that we get all.
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* IPI handler is already set by the panic cpu initially. Therefore,
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* all cpus could invoke this handler from die() and the panic CPU
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* will call machine_kexec() directly from this handler to do
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* kexec boot.
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*/
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if (atomic_read(&waiting_for_crash_ipi))
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printk(KERN_ALERT "done waiting: %d cpus not responding\n",
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atomic_read(&waiting_for_crash_ipi));
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/* Leave the IPI callback set */
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}
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#else
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static void crash_kexec_prepare_cpus(void)
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{
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/*
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* move the secondarys to us so that we can copy
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* the new kernel 0-0x100 safely
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*
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* do this if kexec in setup.c ?
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*/
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smp_release_cpus();
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}
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#endif
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void default_machine_crash_shutdown(struct pt_regs *regs)
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{
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/*
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* This function is only called after the system
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* has paniced or is otherwise in a critical state.
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* The minimum amount of code to allow a kexec'd kernel
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* to run successfully needs to happen here.
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*
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* In practice this means stopping other cpus in
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* an SMP system.
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* The kernel is broken so disable interrupts.
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*/
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local_irq_disable();
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if (ppc_md.kexec_cpu_down)
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ppc_md.kexec_cpu_down(1, 0);
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/*
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* Make a note of crashing cpu. Will be used in machine_kexec
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* such that another IPI will not be sent.
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*/
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crashing_cpu = smp_processor_id();
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crash_kexec_prepare_cpus();
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crash_save_this_cpu(regs, crashing_cpu);
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}
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