diff mbox series

[6/7] x86: kexec_file: clean up prepare_elf64_headers()

Message ID 20180227044814.24808-7-takahiro.akashi@linaro.org
State Superseded
Headers show
Series kexec_file: refactoring for other architecutres | expand

Commit Message

AKASHI Takahiro Feb. 27, 2018, 4:48 a.m. UTC 
removing bufp variable in prepare_elf64_headers() makes the code simpler
and more understandable.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

Cc: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
---
 arch/x86/kernel/crash.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

-- 
2.16.2

Comments

Dave Young March 2, 2018, 5:39 a.m. UTC | #1 
On 02/27/18 at 01:48pm, AKASHI Takahiro wrote:
> removing bufp variable in prepare_elf64_headers() makes the code simpler

> and more understandable.

> 

> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

> Cc: Dave Young <dyoung@redhat.com>

> Cc: Vivek Goyal <vgoyal@redhat.com>

> Cc: Baoquan He <bhe@redhat.com>

> ---

>  arch/x86/kernel/crash.c | 18 +++++++-----------

>  1 file changed, 7 insertions(+), 11 deletions(-)

> 

> diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c

> index bfc37ad20d4a..a842fd847684 100644

> --- a/arch/x86/kernel/crash.c

> +++ b/arch/x86/kernel/crash.c

> @@ -334,7 +334,7 @@ static int prepare_elf64_headers(struct crash_mem *cmem, int kernel_map,

>  	Elf64_Ehdr *ehdr;

>  	Elf64_Phdr *phdr;

>  	unsigned long nr_cpus = num_possible_cpus(), nr_phdr, elf_sz;

> -	unsigned char *buf, *bufp;

> +	unsigned char *buf;

>  	unsigned int cpu, i;

>  	unsigned long long notes_addr;

>  	unsigned long mstart, mend;

> @@ -359,9 +359,8 @@ static int prepare_elf64_headers(struct crash_mem *cmem, int kernel_map,

>  	if (!buf)

>  		return -ENOMEM;

>  

> -	bufp = buf;

> -	ehdr = (Elf64_Ehdr *)bufp;

> -	bufp += sizeof(Elf64_Ehdr);

> +	ehdr = (Elf64_Ehdr *)buf;

> +	phdr = (Elf64_Phdr *)(ehdr + 1);


phdr should start with ehdr + sizeof(Elf64_Ehdr);

>  	memcpy(ehdr->e_ident, ELFMAG, SELFMAG);

>  	ehdr->e_ident[EI_CLASS] = ELFCLASS64;

>  	ehdr->e_ident[EI_DATA] = ELFDATA2LSB;

> @@ -377,33 +376,30 @@ static int prepare_elf64_headers(struct crash_mem *cmem, int kernel_map,

>  

>  	/* Prepare one phdr of type PT_NOTE for each present cpu */

>  	for_each_present_cpu(cpu) {

> -		phdr = (Elf64_Phdr *)bufp;

> -		bufp += sizeof(Elf64_Phdr);

>  		phdr->p_type = PT_NOTE;

>  		notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu));

>  		phdr->p_offset = phdr->p_paddr = notes_addr;

>  		phdr->p_filesz = phdr->p_memsz = sizeof(note_buf_t);

>  		(ehdr->e_phnum)++;

> +		phdr++;

>  	}

>  

>  	/* Prepare one PT_NOTE header for vmcoreinfo */

> -	phdr = (Elf64_Phdr *)bufp;

> -	bufp += sizeof(Elf64_Phdr);

>  	phdr->p_type = PT_NOTE;

>  	phdr->p_offset = phdr->p_paddr = paddr_vmcoreinfo_note();

>  	phdr->p_filesz = phdr->p_memsz = VMCOREINFO_NOTE_SIZE;

>  	(ehdr->e_phnum)++;

> +	phdr++;

>  

>  	/* Prepare PT_LOAD type program header for kernel text region */

>  	if (kernel_map) {

> -		phdr = (Elf64_Phdr *)bufp;

> -		bufp += sizeof(Elf64_Phdr);

>  		phdr->p_type = PT_LOAD;

>  		phdr->p_flags = PF_R|PF_W|PF_X;

>  		phdr->p_vaddr = (Elf64_Addr)_text;

>  		phdr->p_filesz = phdr->p_memsz = _end - _text;

>  		phdr->p_offset = phdr->p_paddr = __pa_symbol(_text);

> -		(ehdr->e_phnum)++;

> +		ehdr->e_phnum++;

> +		phdr++;

>  	}

>  

>  	/* Go through all the ranges in cmem->ranges[] and prepare phdr */

> -- 

> 2.16.2

> 


Thanks
Dave
AKASHI Takahiro March 2, 2018, 5:58 a.m. UTC | #2 
On Fri, Mar 02, 2018 at 01:39:45PM +0800, Dave Young wrote:
> On 02/27/18 at 01:48pm, AKASHI Takahiro wrote:

> > removing bufp variable in prepare_elf64_headers() makes the code simpler

> > and more understandable.

> > 

> > Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

> > Cc: Dave Young <dyoung@redhat.com>

> > Cc: Vivek Goyal <vgoyal@redhat.com>

> > Cc: Baoquan He <bhe@redhat.com>

> > ---

> >  arch/x86/kernel/crash.c | 18 +++++++-----------

> >  1 file changed, 7 insertions(+), 11 deletions(-)

> > 

> > diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c

> > index bfc37ad20d4a..a842fd847684 100644

> > --- a/arch/x86/kernel/crash.c

> > +++ b/arch/x86/kernel/crash.c

> > @@ -334,7 +334,7 @@ static int prepare_elf64_headers(struct crash_mem *cmem, int kernel_map,

> >  	Elf64_Ehdr *ehdr;

> >  	Elf64_Phdr *phdr;

> >  	unsigned long nr_cpus = num_possible_cpus(), nr_phdr, elf_sz;

> > -	unsigned char *buf, *bufp;

> > +	unsigned char *buf;

> >  	unsigned int cpu, i;

> >  	unsigned long long notes_addr;

> >  	unsigned long mstart, mend;

> > @@ -359,9 +359,8 @@ static int prepare_elf64_headers(struct crash_mem *cmem, int kernel_map,

> >  	if (!buf)

> >  		return -ENOMEM;

> >  

> > -	bufp = buf;

> > -	ehdr = (Elf64_Ehdr *)bufp;

> > -	bufp += sizeof(Elf64_Ehdr);

> > +	ehdr = (Elf64_Ehdr *)buf;

> > +	phdr = (Elf64_Phdr *)(ehdr + 1);

> 

> phdr should start with ehdr + sizeof(Elf64_Ehdr);


Well, it's a matter of rhetoric :)
The values from both expressions are the same.
Or do you mean my expression is confusing?

-Takahiro AKASHI


> >  	memcpy(ehdr->e_ident, ELFMAG, SELFMAG);

> >  	ehdr->e_ident[EI_CLASS] = ELFCLASS64;

> >  	ehdr->e_ident[EI_DATA] = ELFDATA2LSB;

> > @@ -377,33 +376,30 @@ static int prepare_elf64_headers(struct crash_mem *cmem, int kernel_map,

> >  

> >  	/* Prepare one phdr of type PT_NOTE for each present cpu */

> >  	for_each_present_cpu(cpu) {

> > -		phdr = (Elf64_Phdr *)bufp;

> > -		bufp += sizeof(Elf64_Phdr);

> >  		phdr->p_type = PT_NOTE;

> >  		notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu));

> >  		phdr->p_offset = phdr->p_paddr = notes_addr;

> >  		phdr->p_filesz = phdr->p_memsz = sizeof(note_buf_t);

> >  		(ehdr->e_phnum)++;

> > +		phdr++;

> >  	}

> >  

> >  	/* Prepare one PT_NOTE header for vmcoreinfo */

> > -	phdr = (Elf64_Phdr *)bufp;

> > -	bufp += sizeof(Elf64_Phdr);

> >  	phdr->p_type = PT_NOTE;

> >  	phdr->p_offset = phdr->p_paddr = paddr_vmcoreinfo_note();

> >  	phdr->p_filesz = phdr->p_memsz = VMCOREINFO_NOTE_SIZE;

> >  	(ehdr->e_phnum)++;

> > +	phdr++;

> >  

> >  	/* Prepare PT_LOAD type program header for kernel text region */

> >  	if (kernel_map) {

> > -		phdr = (Elf64_Phdr *)bufp;

> > -		bufp += sizeof(Elf64_Phdr);

> >  		phdr->p_type = PT_LOAD;

> >  		phdr->p_flags = PF_R|PF_W|PF_X;

> >  		phdr->p_vaddr = (Elf64_Addr)_text;

> >  		phdr->p_filesz = phdr->p_memsz = _end - _text;

> >  		phdr->p_offset = phdr->p_paddr = __pa_symbol(_text);

> > -		(ehdr->e_phnum)++;

> > +		ehdr->e_phnum++;

> > +		phdr++;

> >  	}

> >  

> >  	/* Go through all the ranges in cmem->ranges[] and prepare phdr */

> > -- 

> > 2.16.2

> > 

> 

> Thanks

> Dave
Dave Young March 2, 2018, 6:04 a.m. UTC | #3 
On 03/02/18 at 02:58pm, AKASHI Takahiro wrote:
> On Fri, Mar 02, 2018 at 01:39:45PM +0800, Dave Young wrote:

> > On 02/27/18 at 01:48pm, AKASHI Takahiro wrote:

> > > removing bufp variable in prepare_elf64_headers() makes the code simpler

> > > and more understandable.

> > > 

> > > Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

> > > Cc: Dave Young <dyoung@redhat.com>

> > > Cc: Vivek Goyal <vgoyal@redhat.com>

> > > Cc: Baoquan He <bhe@redhat.com>

> > > ---

> > >  arch/x86/kernel/crash.c | 18 +++++++-----------

> > >  1 file changed, 7 insertions(+), 11 deletions(-)

> > > 

> > > diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c

> > > index bfc37ad20d4a..a842fd847684 100644

> > > --- a/arch/x86/kernel/crash.c

> > > +++ b/arch/x86/kernel/crash.c

> > > @@ -334,7 +334,7 @@ static int prepare_elf64_headers(struct crash_mem *cmem, int kernel_map,

> > >  	Elf64_Ehdr *ehdr;

> > >  	Elf64_Phdr *phdr;

> > >  	unsigned long nr_cpus = num_possible_cpus(), nr_phdr, elf_sz;

> > > -	unsigned char *buf, *bufp;

> > > +	unsigned char *buf;

> > >  	unsigned int cpu, i;

> > >  	unsigned long long notes_addr;

> > >  	unsigned long mstart, mend;

> > > @@ -359,9 +359,8 @@ static int prepare_elf64_headers(struct crash_mem *cmem, int kernel_map,

> > >  	if (!buf)

> > >  		return -ENOMEM;

> > >  

> > > -	bufp = buf;

> > > -	ehdr = (Elf64_Ehdr *)bufp;

> > > -	bufp += sizeof(Elf64_Ehdr);

> > > +	ehdr = (Elf64_Ehdr *)buf;

> > > +	phdr = (Elf64_Phdr *)(ehdr + 1);

> > 

> > phdr should start with ehdr + sizeof(Elf64_Ehdr);

> 

> Well, it's a matter of rhetoric :)

> The values from both expressions are the same.

> Or do you mean my expression is confusing?


Oops, I interpret it as (Elf64_Phdr *)ehdr + 1;

Please ignore this comment then.

> 

> -Takahiro AKASHI

> 

> 

> > >  	memcpy(ehdr->e_ident, ELFMAG, SELFMAG);

> > >  	ehdr->e_ident[EI_CLASS] = ELFCLASS64;

> > >  	ehdr->e_ident[EI_DATA] = ELFDATA2LSB;

> > > @@ -377,33 +376,30 @@ static int prepare_elf64_headers(struct crash_mem *cmem, int kernel_map,

> > >  

> > >  	/* Prepare one phdr of type PT_NOTE for each present cpu */

> > >  	for_each_present_cpu(cpu) {

> > > -		phdr = (Elf64_Phdr *)bufp;

> > > -		bufp += sizeof(Elf64_Phdr);

> > >  		phdr->p_type = PT_NOTE;

> > >  		notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu));

> > >  		phdr->p_offset = phdr->p_paddr = notes_addr;

> > >  		phdr->p_filesz = phdr->p_memsz = sizeof(note_buf_t);

> > >  		(ehdr->e_phnum)++;

> > > +		phdr++;

> > >  	}

> > >  

> > >  	/* Prepare one PT_NOTE header for vmcoreinfo */

> > > -	phdr = (Elf64_Phdr *)bufp;

> > > -	bufp += sizeof(Elf64_Phdr);

> > >  	phdr->p_type = PT_NOTE;

> > >  	phdr->p_offset = phdr->p_paddr = paddr_vmcoreinfo_note();

> > >  	phdr->p_filesz = phdr->p_memsz = VMCOREINFO_NOTE_SIZE;

> > >  	(ehdr->e_phnum)++;

> > > +	phdr++;

> > >  

> > >  	/* Prepare PT_LOAD type program header for kernel text region */

> > >  	if (kernel_map) {

> > > -		phdr = (Elf64_Phdr *)bufp;

> > > -		bufp += sizeof(Elf64_Phdr);

> > >  		phdr->p_type = PT_LOAD;

> > >  		phdr->p_flags = PF_R|PF_W|PF_X;

> > >  		phdr->p_vaddr = (Elf64_Addr)_text;

> > >  		phdr->p_filesz = phdr->p_memsz = _end - _text;

> > >  		phdr->p_offset = phdr->p_paddr = __pa_symbol(_text);

> > > -		(ehdr->e_phnum)++;

> > > +		ehdr->e_phnum++;

> > > +		phdr++;

> > >  	}

> > >  

> > >  	/* Go through all the ranges in cmem->ranges[] and prepare phdr */

> > > -- 

> > > 2.16.2

> > > 

> > 

> > Thanks

> > Dave
diff mbox series

Patch

diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index bfc37ad20d4a..a842fd847684 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -334,7 +334,7 @@  static int prepare_elf64_headers(struct crash_mem *cmem, int kernel_map,
 	Elf64_Ehdr *ehdr;
 	Elf64_Phdr *phdr;
 	unsigned long nr_cpus = num_possible_cpus(), nr_phdr, elf_sz;
-	unsigned char *buf, *bufp;
+	unsigned char *buf;
 	unsigned int cpu, i;
 	unsigned long long notes_addr;
 	unsigned long mstart, mend;
@@ -359,9 +359,8 @@  static int prepare_elf64_headers(struct crash_mem *cmem, int kernel_map,
 	if (!buf)
 		return -ENOMEM;
 
-	bufp = buf;
-	ehdr = (Elf64_Ehdr *)bufp;
-	bufp += sizeof(Elf64_Ehdr);
+	ehdr = (Elf64_Ehdr *)buf;
+	phdr = (Elf64_Phdr *)(ehdr + 1);
 	memcpy(ehdr->e_ident, ELFMAG, SELFMAG);
 	ehdr->e_ident[EI_CLASS] = ELFCLASS64;
 	ehdr->e_ident[EI_DATA] = ELFDATA2LSB;
@@ -377,33 +376,30 @@  static int prepare_elf64_headers(struct crash_mem *cmem, int kernel_map,
 
 	/* Prepare one phdr of type PT_NOTE for each present cpu */
 	for_each_present_cpu(cpu) {
-		phdr = (Elf64_Phdr *)bufp;
-		bufp += sizeof(Elf64_Phdr);
 		phdr->p_type = PT_NOTE;
 		notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu));
 		phdr->p_offset = phdr->p_paddr = notes_addr;
 		phdr->p_filesz = phdr->p_memsz = sizeof(note_buf_t);
 		(ehdr->e_phnum)++;
+		phdr++;
 	}
 
 	/* Prepare one PT_NOTE header for vmcoreinfo */
-	phdr = (Elf64_Phdr *)bufp;
-	bufp += sizeof(Elf64_Phdr);
 	phdr->p_type = PT_NOTE;
 	phdr->p_offset = phdr->p_paddr = paddr_vmcoreinfo_note();
 	phdr->p_filesz = phdr->p_memsz = VMCOREINFO_NOTE_SIZE;
 	(ehdr->e_phnum)++;
+	phdr++;
 
 	/* Prepare PT_LOAD type program header for kernel text region */
 	if (kernel_map) {
-		phdr = (Elf64_Phdr *)bufp;
-		bufp += sizeof(Elf64_Phdr);
 		phdr->p_type = PT_LOAD;
 		phdr->p_flags = PF_R|PF_W|PF_X;
 		phdr->p_vaddr = (Elf64_Addr)_text;
 		phdr->p_filesz = phdr->p_memsz = _end - _text;
 		phdr->p_offset = phdr->p_paddr = __pa_symbol(_text);
-		(ehdr->e_phnum)++;
+		ehdr->e_phnum++;
+		phdr++;
 	}
 
 	/* Go through all the ranges in cmem->ranges[] and prepare phdr */