linux-kernel - Re: [PATCH] kexec: Move some memembers and definitions within the scope of CONFIG_KEXEC

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Message-ID: <567936B7.5020702@redhat.com>
Date:	Tue, 22 Dec 2015 19:40:39 +0800
From:	Xunlei Pang <xlpang@...hat.com>
To:	Minfei Huang <mhuang@...hat.com>
Cc:	linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
	akpm@...ux-foundation.org, dyoung@...hat.com, ebiederm@...ssion.com
Subject: Re: [PATCH] kexec: Move some memembers and definitions within the
 scope of CONFIG_KEXEC_FILE

On 12/22/2015 at 06:47 PM, Minfei Huang wrote:
> On 12/21/15 at 02:09pm, Xunlei Pang wrote:
>> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
>> index 7b68d27..2cc643c 100644
>> --- a/include/linux/kexec.h
>> +++ b/include/linux/kexec.h
>> @@ -109,11 +109,7 @@ struct compat_kexec_segment {
>>  };
>>  #endif
>>  
>> -struct kexec_sha_region {
>> -	unsigned long start;
>> -	unsigned long len;
>> -};
>> -
>> +#ifdef CONFIG_KEXEC_FILE
>>  struct purgatory_info {
>>  	/* Pointer to elf header of read only purgatory */
>>  	Elf_Ehdr *ehdr;
>> @@ -130,6 +126,28 @@ struct purgatory_info {
>>  	unsigned long purgatory_load_addr;
>>  };
>>  
>> +typedef int (kexec_probe_t)(const char *kernel_buf, unsigned long kernel_size);
>> +typedef void *(kexec_load_t)(struct kimage *image, char *kernel_buf,
>> +			     unsigned long kernel_len, char *initrd,
>> +			     unsigned long initrd_len, char *cmdline,
>> +			     unsigned long cmdline_len);
>> +typedef int (kexec_cleanup_t)(void *loader_data);
>> +
>> +#ifdef CONFIG_KEXEC_VERIFY_SIG
>> +typedef int (kexec_verify_sig_t)(const char *kernel_buf,
>> +				 unsigned long kernel_len);
>> +#endif
>> +
>> +struct kexec_file_ops {
>> +	kexec_probe_t *probe;
>> +	kexec_load_t *load;
>> +	kexec_cleanup_t *cleanup;
>> +#ifdef CONFIG_KEXEC_VERIFY_SIG
>> +	kexec_verify_sig_t *verify_sig;
>> +#endif
>> +};
>> +#endif
>> +
>>  struct kimage {
>>  	kimage_entry_t head;
>>  	kimage_entry_t *entry;
>> @@ -161,6 +179,7 @@ struct kimage {
>>  	struct kimage_arch arch;
>>  #endif
>>  
>> +#ifdef CONFIG_KEXEC_FILE
>>  	/* Additional fields for file based kexec syscall */
>>  	void *kernel_buf;
>>  	unsigned long kernel_buf_len;
>> @@ -179,38 +198,7 @@ struct kimage {
>>  
>>  	/* Information for loading purgatory */
>>  	struct purgatory_info purgatory_info;
>> -};
>> -
>> -/*
>> - * Keeps track of buffer parameters as provided by caller for requesting
>> - * memory placement of buffer.
>> - */
>> -struct kexec_buf {
>> -	struct kimage *image;
>> -	char *buffer;
>> -	unsigned long bufsz;
>> -	unsigned long mem;
>> -	unsigned long memsz;
>> -	unsigned long buf_align;
>> -	unsigned long buf_min;
>> -	unsigned long buf_max;
>> -	bool top_down;		/* allocate from top of memory hole */
>> -};
>> -
>> -typedef int (kexec_probe_t)(const char *kernel_buf, unsigned long kernel_size);
>> -typedef void *(kexec_load_t)(struct kimage *image, char *kernel_buf,
>> -			     unsigned long kernel_len, char *initrd,
>> -			     unsigned long initrd_len, char *cmdline,
>> -			     unsigned long cmdline_len);
>> -typedef int (kexec_cleanup_t)(void *loader_data);
>> -typedef int (kexec_verify_sig_t)(const char *kernel_buf,
>> -				 unsigned long kernel_len);
>> -
>> -struct kexec_file_ops {
>> -	kexec_probe_t *probe;
>> -	kexec_load_t *load;
>> -	kexec_cleanup_t *cleanup;
>> -	kexec_verify_sig_t *verify_sig;
>> +#endif
>>  };
>>  
>>  /* kexec interface functions */
> Hi, Xunlei.
>
> Following functions will be used only in kexec_file. Please wrap them in
> CONFIG_KEXEC_FILE.
>
> int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
> 					 unsigned long buf_len);
> void * __weak arch_kexec_kernel_image_load(struct kimage *image);
> int __weak arch_kimage_file_post_load_cleanup(struct kimage *image);
> int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
> 					unsigned long buf_len);
> int __weak arch_kexec_apply_relocations_add(const Elf_Ehdr *ehdr,
> 					Elf_Shdr *sechdrs, unsigned int relsec);
> int __weak arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
> 					unsigned int relsec);

Thanks for the comment.

I noticed this as well, but seems for the function declarations we don't need do this,
since they don't consume the actual space.

For example, in the include/linux/timekeeping.h
/*  
 * RTC specific
 */ 
extern bool timekeeping_rtc_skipsuspend(void);
extern bool timekeeping_rtc_skipresume(void);

extern void timekeeping_inject_sleeptime64(struct timespec64 *delta);

also not embraced by the corresponding macros.

Regards,
Xunlei

>
> Thanks
> Minfei

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