Let's start bundling the writes of the headers and of the data so we
have a clear ordering between them. Since the ELF header uses offsets
to the headers we can freely order them.
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
dump/dump.c | 31 ++++++++++++++-----------------
1 file changed, 14 insertions(+), 17 deletions(-)
diff --git a/dump/dump.c b/dump/dump.c
index e7a3b54ebe..b168a25321 100644
--- a/dump/dump.c
+++ b/dump/dump.c
@@ -583,6 +583,8 @@ static void dump_begin(DumpState *s, Error **errp)
* --------------
* | elf header |
* --------------
+ * | sctn_hdr |
+ * --------------
* | PT_NOTE |
* --------------
* | PT_LOAD |
@@ -591,8 +593,6 @@ static void dump_begin(DumpState *s, Error **errp)
* --------------
* | PT_LOAD |
* --------------
- * | sec_hdr |
- * --------------
* | elf note |
* --------------
* | memory |
@@ -608,6 +608,12 @@ static void dump_begin(DumpState *s, Error **errp)
return;
}
+ /* write section headers to vmcore */
+ write_elf_section_headers(s, errp);
+ if (*errp) {
+ return;
+ }
+
/* write PT_NOTE to vmcore */
write_elf_phdr_note(s, errp);
if (*errp) {
@@ -620,12 +626,6 @@ static void dump_begin(DumpState *s, Error **errp)
return;
}
- /* write section headers to vmcore */
- write_elf_section_headers(s, errp);
- if (*errp) {
- return;
- }
-
/* write notes to vmcore */
write_elf_notes(s, errp);
}
@@ -1868,16 +1868,13 @@ static void dump_init(DumpState *s, int fd, bool has_format,
}
if (dump_is_64bit(s)) {
- s->phdr_offset = sizeof(Elf64_Ehdr);
- s->shdr_offset = s->phdr_offset + sizeof(Elf64_Phdr) * s->phdr_num;
- s->note_offset = s->shdr_offset + sizeof(Elf64_Shdr) * s->shdr_num;
- s->memory_offset = s->note_offset + s->note_size;
+ s->shdr_offset = sizeof(Elf64_Ehdr);
+ s->phdr_offset = s->shdr_offset + sizeof(Elf64_Shdr) * s->shdr_num;
+ s->note_offset = s->phdr_offset + sizeof(Elf64_Phdr) * s->phdr_num;
} else {
-
- s->phdr_offset = sizeof(Elf32_Ehdr);
- s->shdr_offset = s->phdr_offset + sizeof(Elf32_Phdr) * s->phdr_num;
- s->note_offset = s->shdr_offset + sizeof(Elf32_Shdr) * s->shdr_num;
- s->memory_offset = s->note_offset + s->note_size;
+ s->shdr_offset = sizeof(Elf32_Ehdr);
+ s->phdr_offset = s->shdr_offset + sizeof(Elf32_Shdr) * s->shdr_num;
+ s->note_offset = s->phdr_offset + sizeof(Elf32_Phdr) * s->phdr_num;
}
return;
--
2.34.1Janosch Frank <frankja@linux.ibm.com> writes: > Let's start bundling the writes of the headers and of the data so we > have a clear ordering between them. Since the ELF header uses offsets > to the headers we can freely order them. > > Signed-off-by: Janosch Frank <frankja@linux.ibm.com> > --- > dump/dump.c | 31 ++++++++++++++----------------- > 1 file changed, 14 insertions(+), 17 deletions(-) > > diff --git a/dump/dump.c b/dump/dump.c > index e7a3b54ebe..b168a25321 100644 > --- a/dump/dump.c > +++ b/dump/dump.c > @@ -583,6 +583,8 @@ static void dump_begin(DumpState *s, Error **errp) > * -------------- > * | elf header | > * -------------- > + * | sctn_hdr | > + * -------------- While you’re at it, I would suggest to add the location for the program headers (phdr) as well. This would it make easier to understand the memory layout & the code below as well. I guess it looks like: … --------------- | sctn_hdr | --------------- | prog_hdr | --------------- … […snip]
On 10/17/22 14:49, Marc Hartmayer wrote:
> Janosch Frank <frankja@linux.ibm.com> writes:
>
>> Let's start bundling the writes of the headers and of the data so we
>> have a clear ordering between them. Since the ELF header uses offsets
>> to the headers we can freely order them.
>>
>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>> ---
>> dump/dump.c | 31 ++++++++++++++-----------------
>> 1 file changed, 14 insertions(+), 17 deletions(-)
>>
>> diff --git a/dump/dump.c b/dump/dump.c
>> index e7a3b54ebe..b168a25321 100644
>> --- a/dump/dump.c
>> +++ b/dump/dump.c
>> @@ -583,6 +583,8 @@ static void dump_begin(DumpState *s, Error **errp)
>> * --------------
>> * | elf header |
>> * --------------
>> + * | sctn_hdr |
>> + * --------------
>
> While you’re at it, I would suggest to add the location for the program
> headers (phdr) as well. This would it make easier to understand the
> memory layout & the code below as well.
>
> I guess it looks like:
>
> …
> ---------------
> | sctn_hdr |
> ---------------
> | prog_hdr |
> ---------------
> …
>
>
> […snip]
>
They are already in there, have a look at the PT_* entries. I've left
them like this because I assumed that the original author wanted to make
a point by having them like this.
* --------------
* | elf header |
* --------------
* | sctn_hdr |
* --------------
* | PT_NOTE |
* --------------
* | PT_LOAD |
* --------------
* | ...... |
* --------------
* | PT_LOAD |
* --------------
Janosch Frank <frankja@linux.ibm.com> writes: > On 10/17/22 14:49, Marc Hartmayer wrote: >> Janosch Frank <frankja@linux.ibm.com> writes: >> >>> Let's start bundling the writes of the headers and of the data so we >>> have a clear ordering between them. Since the ELF header uses offsets >>> to the headers we can freely order them. >>> >>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com> >>> --- >>> dump/dump.c | 31 ++++++++++++++----------------- >>> 1 file changed, 14 insertions(+), 17 deletions(-) >>> >>> diff --git a/dump/dump.c b/dump/dump.c >>> index e7a3b54ebe..b168a25321 100644 >>> --- a/dump/dump.c >>> +++ b/dump/dump.c >>> @@ -583,6 +583,8 @@ static void dump_begin(DumpState *s, Error **errp) >>> * -------------- >>> * | elf header | >>> * -------------- >>> + * | sctn_hdr | >>> + * -------------- >> >> While you’re at it, I would suggest to add the location for the program >> headers (phdr) as well. This would it make easier to understand the >> memory layout & the code below as well. >> >> I guess it looks like: >> >> … >> --------------- >> | sctn_hdr | >> --------------- >> | prog_hdr | >> --------------- >> … >> >> >> […snip] >> > > > They are already in there, have a look at the PT_* entries. I've left > them like this because I assumed that the original author wanted to make > a point by having them like this. Makes sense - I mistakenly assumed that these were the actual segment contents. […snip]
On Mon, Oct 17, 2022 at 12:39 PM Janosch Frank <frankja@linux.ibm.com>
wrote:
> Let's start bundling the writes of the headers and of the data so we
> have a clear ordering between them. Since the ELF header uses offsets
> to the headers we can freely order them.
>
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
> dump/dump.c | 31 ++++++++++++++-----------------
> 1 file changed, 14 insertions(+), 17 deletions(-)
>
> diff --git a/dump/dump.c b/dump/dump.c
> index e7a3b54ebe..b168a25321 100644
> --- a/dump/dump.c
> +++ b/dump/dump.c
> @@ -583,6 +583,8 @@ static void dump_begin(DumpState *s, Error **errp)
> * --------------
> * | elf header |
> * --------------
> + * | sctn_hdr |
> + * --------------
> * | PT_NOTE |
> * --------------
> * | PT_LOAD |
> @@ -591,8 +593,6 @@ static void dump_begin(DumpState *s, Error **errp)
> * --------------
> * | PT_LOAD |
> * --------------
> - * | sec_hdr |
> - * --------------
> * | elf note |
> * --------------
> * | memory |
> @@ -608,6 +608,12 @@ static void dump_begin(DumpState *s, Error **errp)
> return;
> }
>
> + /* write section headers to vmcore */
> + write_elf_section_headers(s, errp);
> + if (*errp) {
> + return;
> + }
> +
> /* write PT_NOTE to vmcore */
> write_elf_phdr_note(s, errp);
> if (*errp) {
> @@ -620,12 +626,6 @@ static void dump_begin(DumpState *s, Error **errp)
> return;
> }
>
> - /* write section headers to vmcore */
> - write_elf_section_headers(s, errp);
> - if (*errp) {
> - return;
> - }
> -
> /* write notes to vmcore */
> write_elf_notes(s, errp);
> }
> @@ -1868,16 +1868,13 @@ static void dump_init(DumpState *s, int fd, bool
> has_format,
> }
>
> if (dump_is_64bit(s)) {
> - s->phdr_offset = sizeof(Elf64_Ehdr);
> - s->shdr_offset = s->phdr_offset + sizeof(Elf64_Phdr) *
> s->phdr_num;
> - s->note_offset = s->shdr_offset + sizeof(Elf64_Shdr) *
> s->shdr_num;
> - s->memory_offset = s->note_offset + s->note_size;
> + s->shdr_offset = sizeof(Elf64_Ehdr);
> + s->phdr_offset = s->shdr_offset + sizeof(Elf64_Shdr) *
> s->shdr_num;
> + s->note_offset = s->phdr_offset + sizeof(Elf64_Phdr) *
> s->phdr_num;
> } else {
> -
> - s->phdr_offset = sizeof(Elf32_Ehdr);
> - s->shdr_offset = s->phdr_offset + sizeof(Elf32_Phdr) *
> s->phdr_num;
> - s->note_offset = s->shdr_offset + sizeof(Elf32_Shdr) *
> s->shdr_num;
> - s->memory_offset = s->note_offset + s->note_size;
> + s->shdr_offset = sizeof(Elf32_Ehdr);
> + s->phdr_offset = s->shdr_offset + sizeof(Elf32_Shdr) *
> s->shdr_num;
> + s->note_offset = s->phdr_offset + sizeof(Elf32_Phdr) *
> s->phdr_num;
> }
>
> return;
> --
> 2.34.1
>
>
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