[PATCH] Kexec / Kdump: Unify elf note code

From: Magnus Damm
Date: Mon Dec 04 2006 - 00:18:49 EST

[PATCH] Kexec / Kdump: Unify elf note code

The elf note saving code is currently duplicated over several architectures.
This cleanup patch simply adds code to a common file and then replaces
the arch-specific code with calls to the newly added code.

The only drawback with this approach is that s390 doesn't fully support
kexec-on-panic which for that arch leads to introduction of unused code.

Signed-Off-By: Magnus Damm <magnus@xxxxxxxxxxxxx>
---

Applies on top of linux-2.6.19.
Builds on i386 and x86_64.

arch/i386/kernel/crash.c | 66 +----------------------------------------
arch/powerpc/kernel/crash.c | 59 +-----------------------------------
arch/x86_64/kernel/crash.c | 69 +------------------------------------------
include/linux/kexec.h | 1
kernel/kexec.c | 56 ++++++++++++++++++++++++++++++++++
5 files changed, 63 insertions(+), 188 deletions(-)

--- 0001/arch/i386/kernel/crash.c
+++ work/arch/i386/kernel/crash.c 2006-12-04 11:40:16.000000000 +0900
@@ -31,68 +31,6 @@
/* This keeps a track of which one is crashing cpu. */
static int crashing_cpu;

-static u32 *append_elf_note(u32 *buf, char *name, unsigned type, void *data,
- size_t data_len)
-{
- struct elf_note note;
-
- note.n_namesz = strlen(name) + 1;
- note.n_descsz = data_len;
- note.n_type = type;
- memcpy(buf, &note, sizeof(note));
- buf += (sizeof(note) +3)/4;
- memcpy(buf, name, note.n_namesz);
- buf += (note.n_namesz + 3)/4;
- memcpy(buf, data, note.n_descsz);
- buf += (note.n_descsz + 3)/4;
-
- return buf;
-}
-
-static void final_note(u32 *buf)
-{
- struct elf_note note;
-
- note.n_namesz = 0;
- note.n_descsz = 0;
- note.n_type = 0;
- memcpy(buf, &note, sizeof(note));
-}
-
-static void crash_save_this_cpu(struct pt_regs *regs, int cpu)
-{
- struct elf_prstatus prstatus;
- u32 *buf;
-
- if ((cpu < 0) || (cpu >= NR_CPUS))
- return;
-
- /* Using ELF notes here is opportunistic.
- * I need a well defined structure format
- * for the data I pass, and I need tags
- * on the data to indicate what information I have
- * squirrelled away. ELF notes happen to provide
- * all of that, so there is no need to invent something new.
- */
- buf = (u32*)per_cpu_ptr(crash_notes, cpu);
- if (!buf)
- return;
- memset(&prstatus, 0, sizeof(prstatus));
- prstatus.pr_pid = current->pid;
- elf_core_copy_regs(&prstatus.pr_reg, regs);
- buf = append_elf_note(buf, "CORE", NT_PRSTATUS, &prstatus,
- sizeof(prstatus));
- final_note(buf);
-}
-
-static void crash_save_self(struct pt_regs *regs)
-{
- int cpu;
-
- cpu = safe_smp_processor_id();
- crash_save_this_cpu(regs, cpu);
-}
-
#if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC)
static atomic_t waiting_for_crash_ipi;

@@ -121,7 +59,7 @@ static int crash_nmi_callback(struct not
crash_fixup_ss_esp(&fixed_regs, regs);
regs = &fixed_regs;
}
- crash_save_this_cpu(regs, cpu);
+ crash_save_cpu(regs, cpu);
disable_local_APIC();
atomic_dec(&waiting_for_crash_ipi);
/* Assume hlt works */
@@ -195,5 +133,5 @@ void machine_crash_shutdown(struct pt_re
#if defined(CONFIG_X86_IO_APIC)
disable_IO_APIC();
#endif
- crash_save_self(regs);
+ crash_save_cpu(regs, safe_smp_processor_id());
}
--- 0001/arch/powerpc/kernel/crash.c
+++ work/arch/powerpc/kernel/crash.c 2006-12-04 11:43:20.000000000 +0900
@@ -46,61 +46,6 @@ int crashing_cpu = -1;
static cpumask_t cpus_in_crash = CPU_MASK_NONE;
cpumask_t cpus_in_sr = CPU_MASK_NONE;

-static u32 *append_elf_note(u32 *buf, char *name, unsigned type, void *data,
- size_t data_len)
-{
- struct elf_note note;
-
- note.n_namesz = strlen(name) + 1;
- note.n_descsz = data_len;
- note.n_type = type;
- memcpy(buf, &note, sizeof(note));
- buf += (sizeof(note) +3)/4;
- memcpy(buf, name, note.n_namesz);
- buf += (note.n_namesz + 3)/4;
- memcpy(buf, data, note.n_descsz);
- buf += (note.n_descsz + 3)/4;
-
- return buf;
-}
-
-static void final_note(u32 *buf)
-{
- struct elf_note note;
-
- note.n_namesz = 0;
- note.n_descsz = 0;
- note.n_type = 0;
- memcpy(buf, &note, sizeof(note));
-}
-
-static void crash_save_this_cpu(struct pt_regs *regs, int cpu)
-{
- struct elf_prstatus prstatus;
- u32 *buf;
-
- if ((cpu < 0) || (cpu >= NR_CPUS))
- return;
-
- /* Using ELF notes here is opportunistic.
- * I need a well defined structure format
- * for the data I pass, and I need tags
- * on the data to indicate what information I have
- * squirrelled away. ELF notes happen to provide
- * all of that that no need to invent something new.
- */
- buf = (u32*)per_cpu_ptr(crash_notes, cpu);
- if (!buf)
- return;
-
- memset(&prstatus, 0, sizeof(prstatus));
- prstatus.pr_pid = current->pid;
- elf_core_copy_regs(&prstatus.pr_reg, regs);
- buf = append_elf_note(buf, "CORE", NT_PRSTATUS, &prstatus,
- sizeof(prstatus));
- final_note(buf);
-}
-
#ifdef CONFIG_SMP
static atomic_t enter_on_soft_reset = ATOMIC_INIT(0);

@@ -113,7 +58,7 @@ void crash_ipi_callback(struct pt_regs *

local_irq_disable();
if (!cpu_isset(cpu, cpus_in_crash))
- crash_save_this_cpu(regs, cpu);
+ crash_save_cpu(regs, cpu);
cpu_set(cpu, cpus_in_crash);

/*
@@ -306,7 +251,7 @@ void default_machine_crash_shutdown(stru
* such that another IPI will not be sent.
*/
crashing_cpu = smp_processor_id();
- crash_save_this_cpu(regs, crashing_cpu);
+ crash_save_cpu(regs, crashing_cpu);
crash_kexec_prepare_cpus(crashing_cpu);
cpu_set(crashing_cpu, cpus_in_crash);
if (ppc_md.kexec_cpu_down)
--- 0001/arch/x86_64/kernel/crash.c
+++ work/arch/x86_64/kernel/crash.c 2006-12-04 11:40:53.000000000 +0900
@@ -28,71 +28,6 @@
/* This keeps a track of which one is crashing cpu. */
static int crashing_cpu;

-static u32 *append_elf_note(u32 *buf, char *name, unsigned type,
- void *data, size_t data_len)
-{
- struct elf_note note;
-
- note.n_namesz = strlen(name) + 1;
- note.n_descsz = data_len;
- note.n_type = type;
- memcpy(buf, &note, sizeof(note));
- buf += (sizeof(note) +3)/4;
- memcpy(buf, name, note.n_namesz);
- buf += (note.n_namesz + 3)/4;
- memcpy(buf, data, note.n_descsz);
- buf += (note.n_descsz + 3)/4;
-
- return buf;
-}
-
-static void final_note(u32 *buf)
-{
- struct elf_note note;
-
- note.n_namesz = 0;
- note.n_descsz = 0;
- note.n_type = 0;
- memcpy(buf, &note, sizeof(note));
-}
-
-static void crash_save_this_cpu(struct pt_regs *regs, int cpu)
-{
- struct elf_prstatus prstatus;
- u32 *buf;
-
- if ((cpu < 0) || (cpu >= NR_CPUS))
- return;
-
- /* Using ELF notes here is opportunistic.
- * I need a well defined structure format
- * for the data I pass, and I need tags
- * on the data to indicate what information I have
- * squirrelled away. ELF notes happen to provide
- * all of that, no need to invent something new.
- */
-
- buf = (u32*)per_cpu_ptr(crash_notes, cpu);
-
- if (!buf)
- return;
-
- memset(&prstatus, 0, sizeof(prstatus));
- prstatus.pr_pid = current->pid;
- elf_core_copy_regs(&prstatus.pr_reg, regs);
- buf = append_elf_note(buf, "CORE", NT_PRSTATUS, &prstatus,
- sizeof(prstatus));
- final_note(buf);
-}
-
-static void crash_save_self(struct pt_regs *regs)
-{
- int cpu;
-
- cpu = smp_processor_id();
- crash_save_this_cpu(regs, cpu);
-}
-
#ifdef CONFIG_SMP
static atomic_t waiting_for_crash_ipi;

@@ -117,7 +52,7 @@ static int crash_nmi_callback(struct not
return NOTIFY_STOP;
local_irq_disable();

- crash_save_this_cpu(regs, cpu);
+ crash_save_cpu(regs, cpu);
disable_local_APIC();
atomic_dec(&waiting_for_crash_ipi);
/* Assume hlt works */
@@ -196,5 +131,5 @@ void machine_crash_shutdown(struct pt_re

disable_IO_APIC();

- crash_save_self(regs);
+ crash_save_cpu(regs, smp_processor_id());
}
--- 0001/include/linux/kexec.h
+++ work/include/linux/kexec.h 2006-12-04 12:04:40.000000000 +0900
@@ -105,6 +105,7 @@ extern struct page *kimage_alloc_control
unsigned int order);
extern void crash_kexec(struct pt_regs *);
int kexec_should_crash(struct task_struct *);
+void crash_save_cpu(struct pt_regs *regs, int cpu);
extern struct kimage *kexec_image;
extern struct kimage *kexec_crash_image;

--- 0001/kernel/kexec.c
+++ work/kernel/kexec.c 2006-12-04 12:05:28.000000000 +0900
@@ -20,6 +20,8 @@
#include <linux/syscalls.h>
#include <linux/ioport.h>
#include <linux/hardirq.h>
+#include <linux/elf.h>
+#include <linux/elfcore.h>

#include <asm/page.h>
#include <asm/uaccess.h>
@@ -1067,6 +1069,60 @@ void crash_kexec(struct pt_regs *regs)
}
}

+static u32 *append_elf_note(u32 *buf, char *name, unsigned type, void *data,
+ size_t data_len)
+{
+ struct elf_note note;
+
+ note.n_namesz = strlen(name) + 1;
+ note.n_descsz = data_len;
+ note.n_type = type;
+ memcpy(buf, &note, sizeof(note));
+ buf += (sizeof(note) + 3)/4;
+ memcpy(buf, name, note.n_namesz);
+ buf += (note.n_namesz + 3)/4;
+ memcpy(buf, data, note.n_descsz);
+ buf += (note.n_descsz + 3)/4;
+
+ return buf;
+}
+
+static void final_note(u32 *buf)
+{
+ struct elf_note note;
+
+ note.n_namesz = 0;
+ note.n_descsz = 0;
+ note.n_type = 0;
+ memcpy(buf, &note, sizeof(note));
+}
+
+void crash_save_cpu(struct pt_regs *regs, int cpu)
+{
+ struct elf_prstatus prstatus;
+ u32 *buf;
+
+ if ((cpu < 0) || (cpu >= NR_CPUS))
+ return;
+
+ /* Using ELF notes here is opportunistic.
+ * I need a well defined structure format
+ * for the data I pass, and I need tags
+ * on the data to indicate what information I have
+ * squirrelled away. ELF notes happen to provide
+ * all of that, so there is no need to invent something new.
+ */
+ buf = (u32*)per_cpu_ptr(crash_notes, cpu);
+ if (!buf)
+ return;
+ memset(&prstatus, 0, sizeof(prstatus));
+ prstatus.pr_pid = current->pid;
+ elf_core_copy_regs(&prstatus.pr_reg, regs);
+ buf = append_elf_note(buf, "CORE", NT_PRSTATUS, &prstatus,
+ sizeof(prstatus));
+ final_note(buf);
+}
+
static int __init crash_notes_memory_init(void)
{
/* Allocate memory for saving cpu registers. */
-
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