RE: [PATCH] kexec/kdump: Use generic elf code on ia64

> -----Original Message-----
> From: Simon Horman [mailto:horms@verge.net.au]
> Sent: 2007年4月16日 16:21
> To: fastboot@lists.osdl.org; linux-ia64@vger.kernel.org
> Cc: Vivek Goyal; Luck, Tony; Zou, Nanhai
> Subject: Re: [PATCH] kexec/kdump: Use generic elf code on ia64
> 
> 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.
> 
> 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@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.htm
> l
> 
>   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!
> 
>  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                   |    2 -
>  5 files changed, 16 insertions(+), 46 deletions(-)
> 
> Index: linux-2.6/arch/ia64/kernel/crash.c
> ===================================================================
> --- linux-2.6.orig/arch/ia64/kernel/crash.c	2007-04-16
> 16:13:57.000000000 +0900
> +++ linux-2.6/arch/ia64/kernel/crash.c	2007-04-16 16:14:52.000000000
> +0900
> @@ -25,44 +25,11 @@
>  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;

There was a concern about struct elf_prstatus is so big on IA64 that it better not to put it on stack, consider crash happen with a deep stack..., So I put the structure into percpu data.

With this patch, it fallbacks to stack.

Thanks
Zou Nan hai

> 
>  	ia64_dump_cpu_regs(dst);
>  	cfm = dst[43];
> @@ -70,13 +37,6 @@
>  	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 @@
>  	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/kexec.h
> ===================================================================
> --- linux-2.6.orig/include/asm-ia64/kexec.h	2007-04-16
> 16:13:57.000000000 +0900
> +++ linux-2.6/include/asm-ia64/kexec.h	2007-04-16 16:14:52.000000000
> +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 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	2007-04-16 16:13:57.000000000
> +0900
> +++ linux-2.6/include/linux/kexec.h	2007-04-16 16:14:52.000000000 +0900
> @@ -128,6 +128,11 @@
>  #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	2007-04-16 16:13:57.000000000 +0900
> +++ linux-2.6/kernel/kexec.c	2007-04-16 16:14:52.000000000 +0900
> @@ -1117,7 +1117,7 @@
>  		return;
>  	memset(&prstatus, 0, sizeof(prstatus));
>  	prstatus.pr_pid = current->pid;
> -	elf_core_copy_regs(&prstatus.pr_reg, regs);
> +	kexec_elf_core_copy_regs(&prstatus.pr_reg, regs);
>  	buf = append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS,
>  		      	      &prstatus, sizeof(prstatus));
>  	final_note(buf);
> Index: linux-2.6/arch/ia64/kernel/machine_kexec.c
> ===================================================================
> --- linux-2.6.orig/arch/ia64/kernel/machine_kexec.c	2007-04-16
> 16:11:23.000000000 +0900
> +++ linux-2.6/arch/ia64/kernel/machine_kexec.c	2007-04-16
> 16:14:52.000000000 +0900
> @@ -84,7 +84,7 @@
> 
>  	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;
>  	}
> 
-
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