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kexec: create a new config option CONFIG_KEXEC_FILE for new syscall

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Currently new system call kexec_file_load() and all the associated code
compiles if CONFIG_KEXEC=y.  But new syscall also compiles purgatory
code which currently uses gcc option -mcmodel=large.  This option seems
to be available only gcc 4.4 onwards.

Hiding new functionality behind a new config option will not break
existing users of old gcc.  Those who wish to enable new functionality
will require new gcc.  Having said that, I am trying to figure out how
can I move away from using -mcmodel=large but that can take a while.

I think there are other advantages of introducing this new config
option.  As this option will be enabled only on x86_64, other arches
don't have to compile generic kexec code which will never be used.  This
new code selects CRYPTO=y and CRYPTO_SHA256=y.  And all other arches had
to do this for CONFIG_KEXEC.  Now with introduction of new config
option, we can remove crypto dependency from other arches.

Now CONFIG_KEXEC_FILE is available only on x86_64.  So whereever I had
CONFIG_X86_64 defined, I got rid of that.

For CONFIG_KEXEC_FILE, instead of doing select CRYPTO=y, I changed it to
"depends on CRYPTO=y".  This should be safer as "select" is not
recursive.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Tested-by: Shaun Ruffell <sruffell@digium.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Vivek Goyal
2014-08-29 15:18:46 -07:00
committed by Linus Torvalds
parent b38af4721f
commit 74ca317c26
8 changed files with 42 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
kernel/kexec.c
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@@ -64,7 +64,9 @@ bool kexec_in_progress = false;
char __weak kexec_purgatory[0];
size_t __weak kexec_purgatory_size = 0;
#ifdef CONFIG_KEXEC_FILE
static int kexec_calculate_store_digests(struct kimage *image);
#endif
/* Location of the reserved area for the crash kernel */
struct resource crashk_res = {
@@ -341,6 +343,7 @@ out_free_image:
return ret;
}
#ifdef CONFIG_KEXEC_FILE
static int copy_file_from_fd(int fd, void **buf, unsigned long *buf_len)
{
struct fd f = fdget(fd);
@@ -612,6 +615,9 @@ out_free_image:
kfree(image);
return ret;
}
#else /* CONFIG_KEXEC_FILE */
static inline void kimage_file_post_load_cleanup(struct kimage *image) { }
#endif /* CONFIG_KEXEC_FILE */
static int kimage_is_destination_range(struct kimage *image,
unsigned long start,
@@ -1375,6 +1381,7 @@ COMPAT_SYSCALL_DEFINE4(kexec_load, compat_ulong_t, entry,
}
#endif
#ifdef CONFIG_KEXEC_FILE
SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
unsigned long, cmdline_len, const char __user *, cmdline_ptr,
unsigned long, flags)
@@ -1451,6 +1458,8 @@ out:
return ret;
}
#endif /* CONFIG_KEXEC_FILE */
void crash_kexec(struct pt_regs *regs)
{
/* Take the kexec_mutex here to prevent sys_kexec_load
@@ -2006,6 +2015,7 @@ static int __init crash_save_vmcoreinfo_init(void)
subsys_initcall(crash_save_vmcoreinfo_init);
#ifdef CONFIG_KEXEC_FILE
static int __kexec_add_segment(struct kimage *image, char *buf,
unsigned long bufsz, unsigned long mem,
unsigned long memsz)
@@ -2682,6 +2692,7 @@ int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
return 0;
}
#endif /* CONFIG_KEXEC_FILE */
/*
* Move into place and start executing a preloaded standalone