[PATCH v6 6/8] vmcore: allocate ELF note segment in the 2nd kernel vmalloc memory

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



? 2013?05?15? 17:06, HATAYAMA Daisuke ??:
> The reasons why we don't allocate ELF note segment in the 1st kernel
> (old memory) on page boundary is to keep backward compatibility for
> old kernels, and that if doing so, we waste not a little memory due to
> round-up operation to fit the memory to page boundary since most of
> the buffers are in per-cpu area.
> 
> ELF notes are per-cpu, so total size of ELF note segments depends on
> number of CPUs. The current maximum number of CPUs on x86_64 is 5192,
> and there's already system with 4192 CPUs in SGI, where total size
> amounts to 1MB. This can be larger in the near future or possibly even
> now on another architecture that has larger size of note per a single
> cpu. Thus, to avoid the case where memory allocation for large block
> fails, we allocate vmcore objects on vmalloc memory.
> 
> This patch adds elfnotes_buf and elfnotes_sz variables to keep pointer
> to the ELF note segment buffer and its size. There's no longer the
> vmcore object that corresponds to the ELF note segment in
> vmcore_list. Accordingly, read_vmcore() has new case for ELF note
> segment and set_vmcore_list_offsets_elf{64,32}() and other helper
> functions starts calculating offset from sum of size of ELF headers
> and size of ELF note segment.
> 
> Signed-off-by: HATAYAMA Daisuke <d.hatayama at jp.fujitsu.com>
> ---

Acked-by: Zhang Yanfei <zhangyanfei at cn.fujitsu.com>

> 
>  fs/proc/vmcore.c |  273 +++++++++++++++++++++++++++++++++++++++++-------------
>  1 files changed, 209 insertions(+), 64 deletions(-)
> 
> diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
> index 6cf7fbd..4e121fda 100644
> --- a/fs/proc/vmcore.c
> +++ b/fs/proc/vmcore.c
> @@ -34,6 +34,9 @@ static char *elfcorebuf;
>  static size_t elfcorebuf_sz;
>  static size_t elfcorebuf_sz_orig;
>  
> +static char *elfnotes_buf;
> +static size_t elfnotes_sz;
> +
>  /* Total size of vmcore file. */
>  static u64 vmcore_size;
>  
> @@ -154,6 +157,26 @@ static ssize_t read_vmcore(struct file *file, char __user *buffer,
>  			return acc;
>  	}
>  
> +	/* Read Elf note segment */
> +	if (*fpos < elfcorebuf_sz + elfnotes_sz) {
> +		void *kaddr;
> +
> +		tsz = elfcorebuf_sz + elfnotes_sz - *fpos;
> +		if (buflen < tsz)
> +			tsz = buflen;
> +		kaddr = elfnotes_buf + *fpos - elfcorebuf_sz;
> +		if (copy_to_user(buffer, kaddr, tsz))
> +			return -EFAULT;
> +		buflen -= tsz;
> +		*fpos += tsz;
> +		buffer += tsz;
> +		acc += tsz;
> +
> +		/* leave now if filled buffer already */
> +		if (buflen == 0)
> +			return acc;
> +	}
> +
>  	list_for_each_entry(m, &vmcore_list, list) {
>  		if (*fpos < m->offset + m->size) {
>  			tsz = m->offset + m->size - *fpos;
> @@ -221,23 +244,33 @@ static u64 __init get_vmcore_size_elf32(char *elfptr, size_t elfsz)
>  	return size;
>  }
>  
> -/* Merges all the PT_NOTE headers into one. */
> -static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz,
> -						struct list_head *vc_list)
> +/**
> + * process_note_headers_elf64 - Perform a variety of processing on ELF
> + * note segments according to the combination of function arguments.
> + *
> + * @ehdr_ptr  - ELF header buffer
> + * @nr_notes  - the number of program header entries of PT_NOTE type
> + * @notes_sz  - total size of ELF note segment
> + * @notes_buf - buffer into which ELF note segment is copied
> + *
> + * Assume @ehdr_ptr is always not NULL. If @nr_notes is not NULL, then
> + * the number of program header entries of PT_NOTE type is assigned to
> + * @nr_notes. If @notes_sz is not NULL, then total size of ELF note
> + * segment, header part plus data part, is assigned to @notes_sz. If
> + * @notes_buf is not NULL, then ELF note segment is copied into
> + * @notes_buf.
> + */
> +static int __init process_note_headers_elf64(const Elf64_Ehdr *ehdr_ptr,
> +					     int *nr_notes, u64 *notes_sz,
> +					     char *notes_buf)
>  {
>  	int i, nr_ptnote=0, rc=0;
> -	char *tmp;
> -	Elf64_Ehdr *ehdr_ptr;
> -	Elf64_Phdr phdr, *phdr_ptr;
> +	Elf64_Phdr *phdr_ptr = (Elf64_Phdr*)(ehdr_ptr + 1);
>  	Elf64_Nhdr *nhdr_ptr;
> -	u64 phdr_sz = 0, note_off;
> +	u64 phdr_sz = 0;
>  
> -	ehdr_ptr = (Elf64_Ehdr *)elfptr;
> -	phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr));
>  	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
> -		int j;
>  		void *notes_section;
> -		struct vmcore *new;
>  		u64 offset, max_sz, sz, real_sz = 0;
>  		if (phdr_ptr->p_type != PT_NOTE)
>  			continue;
> @@ -253,7 +286,7 @@ static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz,
>  			return rc;
>  		}
>  		nhdr_ptr = notes_section;
> -		for (j = 0; j < max_sz; j += sz) {
> +		while (real_sz < max_sz) {
>  			if (nhdr_ptr->n_namesz == 0)
>  				break;
>  			sz = sizeof(Elf64_Nhdr) +
> @@ -262,20 +295,68 @@ static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz,
>  			real_sz += sz;
>  			nhdr_ptr = (Elf64_Nhdr*)((char*)nhdr_ptr + sz);
>  		}
> -
> -		/* Add this contiguous chunk of notes section to vmcore list.*/
> -		new = get_new_element();
> -		if (!new) {
> -			kfree(notes_section);
> -			return -ENOMEM;
> +		if (notes_buf) {
> +			offset = phdr_ptr->p_offset;
> +			rc = read_from_oldmem(notes_buf + phdr_sz, real_sz,
> +					      &offset, 0);
> +			if (rc < 0) {
> +				kfree(notes_section);
> +				return rc;
> +			}
>  		}
> -		new->paddr = phdr_ptr->p_offset;
> -		new->size = real_sz;
> -		list_add_tail(&new->list, vc_list);
>  		phdr_sz += real_sz;
>  		kfree(notes_section);
>  	}
>  
> +	if (nr_notes)
> +		*nr_notes = nr_ptnote;
> +	if (notes_sz)
> +		*notes_sz = phdr_sz;
> +
> +	return 0;
> +}
> +
> +static int __init get_note_number_and_size_elf64(const Elf64_Ehdr *ehdr_ptr,
> +						 int *nr_ptnote, u64 *phdr_sz)
> +{
> +	return process_note_headers_elf64(ehdr_ptr, nr_ptnote, phdr_sz, NULL);
> +}
> +
> +static int __init copy_notes_elf64(const Elf64_Ehdr *ehdr_ptr, char *notes_buf)
> +{
> +	return process_note_headers_elf64(ehdr_ptr, NULL, NULL, notes_buf);
> +}
> +
> +/* Merges all the PT_NOTE headers into one. */
> +static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz,
> +					   char **notes_buf, size_t *notes_sz)
> +{
> +	int i, nr_ptnote=0, rc=0;
> +	char *tmp;
> +	Elf64_Ehdr *ehdr_ptr;
> +	Elf64_Phdr phdr;
> +	u64 phdr_sz = 0, note_off;
> +	struct vm_struct *vm;
> +
> +	ehdr_ptr = (Elf64_Ehdr *)elfptr;
> +
> +	rc = get_note_number_and_size_elf64(ehdr_ptr, &nr_ptnote, &phdr_sz);
> +	if (rc < 0)
> +		return rc;
> +
> +	*notes_sz = roundup(phdr_sz, PAGE_SIZE);
> +	*notes_buf = vzalloc(*notes_sz);
> +	if (!*notes_buf)
> +		return -ENOMEM;
> +
> +	vm = find_vm_area(*notes_buf);
> +	BUG_ON(!vm);
> +	vm->flags |= VM_USERMAP;
> +
> +	rc = copy_notes_elf64(ehdr_ptr, *notes_buf);
> +	if (rc < 0)
> +		return rc;
> +
>  	/* Prepare merged PT_NOTE program header. */
>  	phdr.p_type    = PT_NOTE;
>  	phdr.p_flags   = 0;
> @@ -304,23 +385,33 @@ static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz,
>  	return 0;
>  }
>  
> -/* Merges all the PT_NOTE headers into one. */
> -static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz,
> -						struct list_head *vc_list)
> +/**
> + * process_note_headers_elf32 - Perform a variety of processing on ELF
> + * note segments according to the combination of function arguments.
> + *
> + * @ehdr_ptr  - ELF header buffer
> + * @nr_notes  - the number of program header entries of PT_NOTE type
> + * @notes_sz  - total size of ELF note segment
> + * @notes_buf - buffer into which ELF note segment is copied
> + *
> + * Assume @ehdr_ptr is always not NULL. If @nr_notes is not NULL, then
> + * the number of program header entries of PT_NOTE type is assigned to
> + * @nr_notes. If @notes_sz is not NULL, then total size of ELF note
> + * segment, header part plus data part, is assigned to @notes_sz. If
> + * @notes_buf is not NULL, then ELF note segment is copied into
> + * @notes_buf.
> + */
> +static int __init process_note_headers_elf32(const Elf32_Ehdr *ehdr_ptr,
> +					     int *nr_notes, u64 *notes_sz,
> +					     char *notes_buf)
>  {
>  	int i, nr_ptnote=0, rc=0;
> -	char *tmp;
> -	Elf32_Ehdr *ehdr_ptr;
> -	Elf32_Phdr phdr, *phdr_ptr;
> +	Elf32_Phdr *phdr_ptr = (Elf32_Phdr*)(ehdr_ptr + 1);
>  	Elf32_Nhdr *nhdr_ptr;
> -	u64 phdr_sz = 0, note_off;
> +	u64 phdr_sz = 0;
>  
> -	ehdr_ptr = (Elf32_Ehdr *)elfptr;
> -	phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr));
>  	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
> -		int j;
>  		void *notes_section;
> -		struct vmcore *new;
>  		u64 offset, max_sz, sz, real_sz = 0;
>  		if (phdr_ptr->p_type != PT_NOTE)
>  			continue;
> @@ -336,7 +427,7 @@ static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz,
>  			return rc;
>  		}
>  		nhdr_ptr = notes_section;
> -		for (j = 0; j < max_sz; j += sz) {
> +		while (real_sz < max_sz) {
>  			if (nhdr_ptr->n_namesz == 0)
>  				break;
>  			sz = sizeof(Elf32_Nhdr) +
> @@ -345,20 +436,68 @@ static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz,
>  			real_sz += sz;
>  			nhdr_ptr = (Elf32_Nhdr*)((char*)nhdr_ptr + sz);
>  		}
> -
> -		/* Add this contiguous chunk of notes section to vmcore list.*/
> -		new = get_new_element();
> -		if (!new) {
> -			kfree(notes_section);
> -			return -ENOMEM;
> +		if (notes_buf) {
> +			offset = phdr_ptr->p_offset;
> +			rc = read_from_oldmem(notes_buf + phdr_sz, real_sz,
> +					      &offset, 0);
> +			if (rc < 0) {
> +				kfree(notes_section);
> +				return rc;
> +			}
>  		}
> -		new->paddr = phdr_ptr->p_offset;
> -		new->size = real_sz;
> -		list_add_tail(&new->list, vc_list);
>  		phdr_sz += real_sz;
>  		kfree(notes_section);
>  	}
>  
> +	if (nr_notes)
> +		*nr_notes = nr_ptnote;
> +	if (notes_sz)
> +		*notes_sz = phdr_sz;
> +
> +	return 0;
> +}
> +
> +static int __init get_note_number_and_size_elf32(const Elf32_Ehdr *ehdr_ptr,
> +						 int *nr_ptnote, u64 *phdr_sz)
> +{
> +	return process_note_headers_elf32(ehdr_ptr, nr_ptnote, phdr_sz, NULL);
> +}
> +
> +static int __init copy_notes_elf32(const Elf32_Ehdr *ehdr_ptr, char *notes_buf)
> +{
> +	return process_note_headers_elf32(ehdr_ptr, NULL, NULL, notes_buf);
> +}
> +
> +/* Merges all the PT_NOTE headers into one. */
> +static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz,
> +					   char **notes_buf, size_t *notes_sz)
> +{
> +	int i, nr_ptnote=0, rc=0;
> +	char *tmp;
> +	Elf32_Ehdr *ehdr_ptr;
> +	Elf32_Phdr phdr;
> +	u64 phdr_sz = 0, note_off;
> +	struct vm_struct *vm;
> +
> +	ehdr_ptr = (Elf32_Ehdr *)elfptr;
> +
> +	rc = get_note_number_and_size_elf32(ehdr_ptr, &nr_ptnote, &phdr_sz);
> +	if (rc < 0)
> +		return rc;
> +
> +	*notes_sz = roundup(phdr_sz, PAGE_SIZE);
> +	*notes_buf = vzalloc(*notes_sz);
> +	if (!*notes_buf)
> +		return -ENOMEM;
> +
> +	vm = find_vm_area(*notes_buf);
> +	BUG_ON(!vm);
> +	vm->flags |= VM_USERMAP;
> +
> +	rc = copy_notes_elf32(ehdr_ptr, *notes_buf);
> +	if (rc < 0)
> +		return rc;
> +
>  	/* Prepare merged PT_NOTE program header. */
>  	phdr.p_type    = PT_NOTE;
>  	phdr.p_flags   = 0;
> @@ -391,6 +530,7 @@ static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz,
>   * the new offset fields of exported program headers. */
>  static int __init process_ptload_program_headers_elf64(char *elfptr,
>  						size_t elfsz,
> +						size_t elfnotes_sz,
>  						struct list_head *vc_list)
>  {
>  	int i;
> @@ -402,8 +542,8 @@ static int __init process_ptload_program_headers_elf64(char *elfptr,
>  	ehdr_ptr = (Elf64_Ehdr *)elfptr;
>  	phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr)); /* PT_NOTE hdr */
>  
> -	/* First program header is PT_NOTE header. */
> -	vmcore_off = elfsz + roundup(phdr_ptr->p_memsz, PAGE_SIZE);
> +	/* Skip Elf header, program headers and Elf note segment. */
> +	vmcore_off = elfsz + elfnotes_sz;
>  
>  	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
>  		u64 paddr, start, end, size;
> @@ -433,6 +573,7 @@ static int __init process_ptload_program_headers_elf64(char *elfptr,
>  
>  static int __init process_ptload_program_headers_elf32(char *elfptr,
>  						size_t elfsz,
> +						size_t elfnotes_sz,
>  						struct list_head *vc_list)
>  {
>  	int i;
> @@ -444,8 +585,8 @@ static int __init process_ptload_program_headers_elf32(char *elfptr,
>  	ehdr_ptr = (Elf32_Ehdr *)elfptr;
>  	phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr)); /* PT_NOTE hdr */
>  
> -	/* First program header is PT_NOTE header. */
> -	vmcore_off = elfsz + roundup(phdr_ptr->p_memsz, PAGE_SIZE);
> +	/* Skip Elf header, program headers and Elf note segment. */
> +	vmcore_off = elfsz + elfnotes_sz;
>  
>  	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
>  		u64 paddr, start, end, size;
> @@ -474,17 +615,15 @@ static int __init process_ptload_program_headers_elf32(char *elfptr,
>  }
>  
>  /* Sets offset fields of vmcore elements. */
> -static void __init set_vmcore_list_offsets_elf64(char *elfptr, size_t elfsz,
> +static void __init set_vmcore_list_offsets_elf64(size_t elfsz,
> +						size_t elfnotes_sz,
>  						struct list_head *vc_list)
>  {
>  	loff_t vmcore_off;
> -	Elf64_Ehdr *ehdr_ptr;
>  	struct vmcore *m;
>  
> -	ehdr_ptr = (Elf64_Ehdr *)elfptr;
> -
> -	/* Skip Elf header and program headers. */
> -	vmcore_off = elfsz;
> +	/* Skip Elf header, program headers and Elf note segment. */
> +	vmcore_off = elfsz + elfnotes_sz;
>  
>  	list_for_each_entry(m, vc_list, list) {
>  		m->offset = vmcore_off;
> @@ -493,17 +632,15 @@ static void __init set_vmcore_list_offsets_elf64(char *elfptr, size_t elfsz,
>  }
>  
>  /* Sets offset fields of vmcore elements. */
> -static void __init set_vmcore_list_offsets_elf32(char *elfptr, size_t elfsz,
> +static void __init set_vmcore_list_offsets_elf32(size_t elfsz,
> +						size_t elfnotes_sz,
>  						struct list_head *vc_list)
>  {
>  	loff_t vmcore_off;
> -	Elf32_Ehdr *ehdr_ptr;
>  	struct vmcore *m;
>  
> -	ehdr_ptr = (Elf32_Ehdr *)elfptr;
> -
> -	/* Skip Elf header and program headers. */
> -	vmcore_off = elfsz;
> +	/* Skip Elf header, program headers and Elf note segment. */
> +	vmcore_off = elfsz + elfnotes_sz;
>  
>  	list_for_each_entry(m, vc_list, list) {
>  		m->offset = vmcore_off;
> @@ -554,20 +691,23 @@ static int __init parse_crash_elf64_headers(void)
>  	}
>  
>  	/* Merge all PT_NOTE headers into one. */
> -	rc = merge_note_headers_elf64(elfcorebuf, &elfcorebuf_sz, &vmcore_list);
> +	rc = merge_note_headers_elf64(elfcorebuf, &elfcorebuf_sz,
> +				      &elfnotes_buf, &elfnotes_sz);
>  	if (rc) {
>  		free_pages((unsigned long)elfcorebuf,
>  			   get_order(elfcorebuf_sz_orig));
>  		return rc;
>  	}
>  	rc = process_ptload_program_headers_elf64(elfcorebuf, elfcorebuf_sz,
> -							&vmcore_list);
> +						  elfnotes_sz,
> +						  &vmcore_list);
>  	if (rc) {
>  		free_pages((unsigned long)elfcorebuf,
>  			   get_order(elfcorebuf_sz_orig));
>  		return rc;
>  	}
> -	set_vmcore_list_offsets_elf64(elfcorebuf, elfcorebuf_sz, &vmcore_list);
> +	set_vmcore_list_offsets_elf64(elfcorebuf_sz, elfnotes_sz,
> +				      &vmcore_list);
>  	return 0;
>  }
>  
> @@ -614,20 +754,23 @@ static int __init parse_crash_elf32_headers(void)
>  	}
>  
>  	/* Merge all PT_NOTE headers into one. */
> -	rc = merge_note_headers_elf32(elfcorebuf, &elfcorebuf_sz, &vmcore_list);
> +	rc = merge_note_headers_elf32(elfcorebuf, &elfcorebuf_sz,
> +				      &elfnotes_buf, &elfnotes_sz);
>  	if (rc) {
>  		free_pages((unsigned long)elfcorebuf,
>  			   get_order(elfcorebuf_sz_orig));
>  		return rc;
>  	}
>  	rc = process_ptload_program_headers_elf32(elfcorebuf, elfcorebuf_sz,
> -								&vmcore_list);
> +						  elfnotes_sz,
> +						  &vmcore_list);
>  	if (rc) {
>  		free_pages((unsigned long)elfcorebuf,
>  			   get_order(elfcorebuf_sz_orig));
>  		return rc;
>  	}
> -	set_vmcore_list_offsets_elf32(elfcorebuf, elfcorebuf_sz, &vmcore_list);
> +	set_vmcore_list_offsets_elf32(elfcorebuf_sz, elfnotes_sz,
> +				      &vmcore_list);
>  	return 0;
>  }
>  
> @@ -706,6 +849,8 @@ void vmcore_cleanup(void)
>  		list_del(&m->list);
>  		kfree(m);
>  	}
> +	vfree(elfnotes_buf);
> +	elfnotes_buf = NULL;
>  	free_pages((unsigned long)elfcorebuf,
>  		   get_order(elfcorebuf_sz_orig));
>  	elfcorebuf = NULL;
> 
> 




[Index of Archives]     [LM Sensors]     [Linux Sound]     [ALSA Users]     [ALSA Devel]     [Linux Audio Users]     [Linux Media]     [Kernel]     [Gimp]     [Yosemite News]     [Linux Media]

  Powered by Linux