Hi Nanhai, could you take a moment to look at this patch to see if it addresses your concern about stack usage? -- Horms H: http://www.vergenet.net/~horms/ W: http://www.valinux.co.jp/en/ On Wed, Apr 25, 2007 at 06:09:05PM +0900, Simon Horman wrote: > Make use of the generic implementation of crash_save_cpu(). > > On ia64 the registers are saved by a kdump-specific function > ia64_dump_cpu_regs() rather than elf_core_copy_regs() which > is used by other architectures via crash_save_cpu(). It seems > that ia64_dump_cpu_regs() and elf_core_copy_regs() are indeed > quite different > > In order to facilitate this kdump_elf_core_copy_regs() > has been created, and it is called by crash_save_cpu(). > By default kdump_elf_core_copy_regs() is just defined to be > elf_core_copy_regs() and ia64 defines its own implementation, > which calls ia64_dump_cpu_regs(). The ia64 version also sets > register 47 in accordance with the code that it replaces. > > crash_save_cpu() has also been modifued to use a pre-alocated, > per-cpu variable for saving the cpu registers, as per the > IA64 specific code that this patch removes. This is > in order to reduce possible stack contention at crash-time. > > The code appears to work, however as the place where the registers > are captured has changed natrually some of their values have also changed. > This makes looking for problems by comparing the new and old output a > little tricky. > > Signed-off-by: Simon Horman <horms at verge.net.au> > > --- > * This patch applies on top of the note size calculation patch > that can be found in mm and at > http://lists.linux-foundation.org/pipermail/fastboot/2007-April/006792.html > > Porting this patch to not require that one is quite trivial. > I can supply a port or a thread containing both patches if it helps. > > * Update > Diff against include/asm-ia64/kexec.h instead of include/asm/kexec.h > Ooops! > > * Updated crash_save_cpu() to use a per-cpu variable for the registers. > As requested by Nanhai Zou > > * This patch does three things, should it be split? > - Makes crash_save_cpu() use a per-cpu variable. > - Adds the kdump_elf_core_copy_regs() macro > - Has IA64 use the generic code (which requires the other two changes). > > * Added CC: kexec at lists.infradead.org, which is the new place for kexec > discussion. > > arch/ia64/kernel/crash.c | 46 ++------------------------------------ > arch/ia64/kernel/machine_kexec.c | 2 - > include/asm-ia64/kexec.h | 7 ++++- > include/linux/kexec.h | 5 ++++ > kernel/kexec.c | 13 +++++++++- > 5 files changed, 26 insertions(+), 47 deletions(-) > Index: linux-2.6/arch/ia64/kernel/crash.c > =================================================================== > --- linux-2.6.orig/arch/ia64/kernel/crash.c 2007-04-25 17:31:54.000000000 +0900 > +++ linux-2.6/arch/ia64/kernel/crash.c 2007-04-25 17:31:55.000000000 +0900 > @@ -25,44 +25,11 @@ static atomic_t kdump_cpu_frozen; > atomic_t kdump_in_progress; > static int kdump_on_init = 1; > > -static inline Elf64_Word > -*append_elf_note(Elf64_Word *buf, char *name, unsigned type, void *data, > - size_t data_len) > -{ > - struct elf_note *note = (struct elf_note *)buf; > - note->n_namesz = strlen(name) + 1; > - note->n_descsz = data_len; > - note->n_type = type; > - buf += (sizeof(*note) + 3)/4; > - memcpy(buf, name, note->n_namesz); > - buf += (note->n_namesz + 3)/4; > - memcpy(buf, data, data_len); > - buf += (data_len + 3)/4; > - return buf; > -} > - > -static void > -final_note(void *buf) > -{ > - memset(buf, 0, sizeof(struct elf_note)); > -} > - > -extern void ia64_dump_cpu_regs(void *); > - > -static DEFINE_PER_CPU(struct elf_prstatus, elf_prstatus); > - > void > -crash_save_this_cpu(void) > +ia64_kexec_elf_core_copy_regs(elf_gregset_t *elfregs, struct pt_regs *regs) > { > - void *buf; > unsigned long cfm, sof, sol; > - > - int cpu = smp_processor_id(); > - struct elf_prstatus *prstatus = &per_cpu(elf_prstatus, cpu); > - > - elf_greg_t *dst = (elf_greg_t *)&(prstatus->pr_reg); > - memset(prstatus, 0, sizeof(*prstatus)); > - prstatus->pr_pid = current->pid; > + elf_greg_t *dst = (elf_greg_t *)elfregs; > > ia64_dump_cpu_regs(dst); > cfm = dst[43]; > @@ -70,13 +37,6 @@ crash_save_this_cpu(void) > sof = cfm & 0x7f; > dst[46] = (unsigned long)ia64_rse_skip_regs((unsigned long *)dst[46], > sof - sol); > - > - buf = (u64 *) per_cpu_ptr(crash_notes, cpu); > - if (!buf) > - return; > - buf = append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS, prstatus, > - sizeof(*prstatus)); > - final_note(buf); > } > > #ifdef CONFIG_SMP > @@ -134,7 +94,7 @@ kdump_cpu_freeze(struct unw_frame_info * > int cpuid; > local_irq_disable(); > cpuid = smp_processor_id(); > - crash_save_this_cpu(); > + crash_save_cpu(NULL, smp_processor_id()); > current->thread.ksp = (__u64)info->sw - 16; > atomic_inc(&kdump_cpu_frozen); > kdump_status[cpuid] = 1; > Index: linux-2.6/include/asm-ia64/kexec.h > =================================================================== > --- linux-2.6.orig/include/asm-ia64/kexec.h 2007-04-25 17:31:54.000000000 +0900 > +++ linux-2.6/include/asm-ia64/kexec.h 2007-04-25 17:31:55.000000000 +0900 > @@ -19,6 +19,9 @@ > flush_icache_range(page_addr, page_addr + PAGE_SIZE); \ > } while(0) > > +#define kexec_elf_core_copy_regs(elfregs, regs) \ > + ia64_kexec_elf_core_copy_regs(elfregs, regs) > + > extern struct kimage *ia64_kimage; > extern const unsigned int relocate_new_kernel_size; > extern void relocate_new_kernel(unsigned long, unsigned long, > @@ -32,7 +35,9 @@ extern struct resource boot_param_res; > extern void kdump_smp_send_stop(void); > extern void kdump_smp_send_init(void); > extern void kexec_disable_iosapic(void); > -extern void crash_save_this_cpu(void); > +extern void ia64_dump_cpu_regs(void *); > +extern void ia64_kexec_elf_core_copy_regs(elf_gregset_t *elfregs, > + struct pt_regs *regs); > struct rsvd_region; > extern unsigned long kdump_find_rsvd_region(unsigned long size, > struct rsvd_region *rsvd_regions, int n); > Index: linux-2.6/include/linux/kexec.h > =================================================================== > --- linux-2.6.orig/include/linux/kexec.h 2007-04-25 17:31:54.000000000 +0900 > +++ linux-2.6/include/linux/kexec.h 2007-04-25 17:31:55.000000000 +0900 > @@ -128,6 +128,11 @@ extern struct kimage *kexec_crash_image; > #define kexec_flush_icache_page(page) > #endif > > +#ifndef kexec_elf_core_copy_regs > +#define kexec_elf_core_copy_regs(elfregs, regs) \ > + elf_core_copy_regs(elfregs, regs) > +#endif > + > #define KEXEC_ON_CRASH 0x00000001 > #define KEXEC_ARCH_MASK 0xffff0000 > > Index: linux-2.6/kernel/kexec.c > =================================================================== > --- linux-2.6.orig/kernel/kexec.c 2007-04-25 17:31:54.000000000 +0900 > +++ linux-2.6/kernel/kexec.c 2007-04-25 17:57:12.000000000 +0900 > @@ -1097,9 +1097,18 @@ static void final_note(u32 *buf) > memcpy(buf, ¬e, sizeof(note)); > } > > +/* > + * There is some concern that on architectures where struct elf_prstatus is > + * large, such as IA64, having elf_prstatus on the stack in > + * crash_save_cpu() could cause problems given that this function > + * is run after a kernel crash has occured. To aleviate this problem > + * a pre-allocated per-cpu value is used instead. > + */ > +static DEFINE_PER_CPU(struct elf_prstatus, elf_prstatus); > + > void crash_save_cpu(struct pt_regs *regs, int cpu) > { > - struct elf_prstatus prstatus; > + struct elf_prstatus *prstatus; > u32 *buf; > > if ((cpu < 0) || (cpu >= NR_CPUS)) > @@ -1107,7 +1116,7 @@ void crash_save_cpu(struct pt_regs *regs > > /* Using ELF notes here is opportunistic. > * I need a well defined structure format > - * for the data I pass, and I need tags > + * for the data I pass, and I need tag)s > * 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. > @@ -1115,11 +1124,12 @@ void crash_save_cpu(struct pt_regs *regs > 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); > + prstatus = &per_cpu(elf_prstatus, cpu); > + memset(prstatus, 0, sizeof(struct elf_prstatus)); > + prstatus->pr_pid = current->pid; > + kexec_elf_core_copy_regs(&(prstatus->pr_reg), regs); > buf = append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS, > - &prstatus, sizeof(prstatus)); > + prstatus, sizeof(struct elf_prstatus)); > final_note(buf); > } > > Index: linux-2.6/arch/ia64/kernel/machine_kexec.c > =================================================================== > --- linux-2.6.orig/arch/ia64/kernel/machine_kexec.c 2007-04-25 17:31:54.000000000 +0900 > +++ linux-2.6/arch/ia64/kernel/machine_kexec.c 2007-04-25 17:31:55.000000000 +0900 > @@ -84,7 +84,7 @@ static void ia64_machine_kexec(struct un > > BUG_ON(!image); > if (image->type == KEXEC_TYPE_CRASH) { > - crash_save_this_cpu(); > + crash_save_cpu(NULL, smp_processor_id()); > current->thread.ksp = (__u64)info->sw - 16; > } > > - > To unsubscribe from this list: send the line "unsubscribe linux-ia64" in > the body of a message to majordomo at vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
