In the most cases, the entry size of rodata is 8 bytes because the
relocation type is 64 bit, but when compling with Clang on LoongArch,
there exists 32 bit relocation type, the entry size of rodata should
be 4 bytes in this case.
This is preparation for later patch on LoongArch, there is no effect
for the other archs with this patch.
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
tools/objtool/check.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 191950551352..19d1263e64e4 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -26,6 +26,10 @@
#define EM_LOONGARCH 258
#endif
+#ifndef R_LARCH_32_PCREL
+#define R_LARCH_32_PCREL 99
+#endif
+
struct alternative {
struct alternative *next;
struct instruction *insn;
@@ -2096,6 +2100,7 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn,
struct reloc *reloc = table;
struct alternative *alt;
unsigned long offset;
+ unsigned long rodata_entry_size;
/*
* Each @reloc is a switch table relocation which points to the target
@@ -2107,8 +2112,15 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn,
if (reloc != table && reloc == next_table)
break;
+ /* Handle the special cases compiled with Clang on LoongArch */
+ if (file->elf->ehdr.e_machine == EM_LOONGARCH &&
+ reloc_type(reloc) == R_LARCH_32_PCREL)
+ rodata_entry_size = 4;
+ else
+ rodata_entry_size = 8;
+
/* Make sure the table entries are consecutive: */
- if (prev_offset && reloc_offset(reloc) != prev_offset + 8)
+ if (prev_offset && reloc_offset(reloc) != prev_offset + rodata_entry_size)
break;
if (reloc->sym->type == STT_SECTION) {
--
2.42.0On Fri, Nov 22, 2024 at 12:49:58PM +0800, Tiezhu Yang wrote: > @@ -2107,8 +2112,15 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn, > if (reloc != table && reloc == next_table) > break; > > + /* Handle the special cases compiled with Clang on LoongArch */ This comment is not helpful at all. A comment is only needed if the code is not already obvious. In that case it should describe what is being done and why. > + if (file->elf->ehdr.e_machine == EM_LOONGARCH && > + reloc_type(reloc) == R_LARCH_32_PCREL) > + rodata_entry_size = 4; > + else > + rodata_entry_size = 8; Is this really loongarch-specific or is it only related to the size of the reloc? Can this be abstracted out to a reloc_size() function like so? https://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux.git/tree/tools/objtool/klp-diff.c?h=objtool-diff#n834 maybe it could live in elf.h. -- Josh
On 11/26/2024 03:02 PM, Josh Poimboeuf wrote: > On Fri, Nov 22, 2024 at 12:49:58PM +0800, Tiezhu Yang wrote: >> @@ -2107,8 +2112,15 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn, >> if (reloc != table && reloc == next_table) >> break; >> >> + /* Handle the special cases compiled with Clang on LoongArch */ > > This comment is not helpful at all. A comment is only needed if the > code is not already obvious. In that case it should describe what is > being done and why. Will remove it. >> + if (file->elf->ehdr.e_machine == EM_LOONGARCH && >> + reloc_type(reloc) == R_LARCH_32_PCREL) >> + rodata_entry_size = 4; >> + else >> + rodata_entry_size = 8; > > Is this really loongarch-specific or is it only related to the size of > the reloc? This is related with the reloc type, but it may be wrong to only check the reloc type to assign the value of rodata_entry_size, becasue the value of reloc type for different archs may be same, so it needs to check ehdr.e_machine and relocation type. > Can this be abstracted out to a reloc_size() function like > so? > > https://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux.git/tree/tools/objtool/klp-diff.c?h=objtool-diff#n834 > > maybe it could live in elf.h. OK, if I understand your comment correctly, this should be an arch-specific function defined in tools/objtool/arch/*/include/arch/elf.h, otherwise it also needs to check ehdr.e_machine in tools/objtool/include/objtool/elf.h. Thanks, Tiezhu
On Tue, Nov 26, 2024 at 06:59:38PM +0800, Tiezhu Yang wrote: > > Can this be abstracted out to a reloc_size() function like > > so? > > > > https://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux.git/tree/tools/objtool/klp-diff.c?h=objtool-diff#n834 > > > > maybe it could live in elf.h. > > OK, if I understand your comment correctly, this should be an > arch-specific function defined in tools/objtool/arch/*/include/arch/elf.h, > otherwise it also needs to check ehdr.e_machine > in tools/objtool/include/objtool/elf.h. It should probably be an arch-specific function in tools/objtool/arch somewhere. -- Josh
On 11/26/2024 06:59 PM, Tiezhu Yang wrote:
> On 11/26/2024 03:02 PM, Josh Poimboeuf wrote:
>> On Fri, Nov 22, 2024 at 12:49:58PM +0800, Tiezhu Yang wrote:
>>> @@ -2107,8 +2112,15 @@ static int add_jump_table(struct objtool_file
>>> *file, struct instruction *insn,
>>> if (reloc != table && reloc == next_table)
>>> break;
>>>
>>> + /* Handle the special cases compiled with Clang on LoongArch */
>>
>> This comment is not helpful at all. A comment is only needed if the
>> code is not already obvious. In that case it should describe what is
>> being done and why.
>
> Will remove it.
>
>>> + if (file->elf->ehdr.e_machine == EM_LOONGARCH &&
>>> + reloc_type(reloc) == R_LARCH_32_PCREL)
>>> + rodata_entry_size = 4;
>>> + else
>>> + rodata_entry_size = 8;
>>
>> Is this really loongarch-specific or is it only related to the size of
>> the reloc?
>
> This is related with the reloc type, but it may be wrong to only
> check the reloc type to assign the value of rodata_entry_size,
> becasue the value of reloc type for different archs may be same,
> so it needs to check ehdr.e_machine and relocation type.
>
>> Can this be abstracted out to a reloc_size() function like
>> so?
>>
>>
>> https://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux.git/tree/tools/objtool/klp-diff.c?h=objtool-diff#n834
>>
>>
>> maybe it could live in elf.h.
>
> OK, if I understand your comment correctly, this should be an
> arch-specific function defined in
> tools/objtool/arch/*/include/arch/elf.h, otherwise it also needs to
> check ehdr.e_machine
> in tools/objtool/include/objtool/elf.h.
There are only macro definitions in
tools/objtool/arch/*/include/arch/elf.h,
so I think it is better to add reloc_size() in
tools/objtool/include/objtool/elf.h,
like this:
static inline unsigned int reloc_size(struct elf *elf, struct reloc *reloc)
{
if (elf->ehdr.e_machine == EM_X86_64) {
switch (reloc_type(reloc)) {
case R_X86_64_32:
case R_X86_64_PC32:
return 4;
case R_X86_64_64:
case R_X86_64_PC64:
return 8;
default:
ERROR("unknown X86_64 reloc type");
}
} else if (elf->ehdr.e_machine == EM_LOONGARCH) {
switch (reloc_type(reloc)) {
case R_LARCH_32:
case R_LARCH_32_PCREL:
return 4;
case R_LARCH_64:
case R_LARCH_64_PCREL:
return 8;
default:
ERROR("unknown LoongArch reloc type");
}
} else {
return 8;
}
}
and call it in check.c, like this:
rodata_entry_size = reloc_size(file->elf, reloc);
What do you think?
Thanks,
Tiezhu
On Tue, Nov 26, 2024 at 09:22:22PM +0800, Tiezhu Yang wrote:
> > OK, if I understand your comment correctly, this should be an
> > arch-specific function defined in
> > tools/objtool/arch/*/include/arch/elf.h, otherwise it also needs to
> > check ehdr.e_machine
> > in tools/objtool/include/objtool/elf.h.
>
> There are only macro definitions in
> tools/objtool/arch/*/include/arch/elf.h,
> so I think it is better to add reloc_size() in
> tools/objtool/include/objtool/elf.h,
> like this:
>
> static inline unsigned int reloc_size(struct elf *elf, struct reloc *reloc)
> {
> if (elf->ehdr.e_machine == EM_X86_64) {
> switch (reloc_type(reloc)) {
> case R_X86_64_32:
> case R_X86_64_PC32:
> return 4;
> case R_X86_64_64:
> case R_X86_64_PC64:
> return 8;
> default:
> ERROR("unknown X86_64 reloc type");
> }
> } else if (elf->ehdr.e_machine == EM_LOONGARCH) {
> switch (reloc_type(reloc)) {
> case R_LARCH_32:
> case R_LARCH_32_PCREL:
> return 4;
> case R_LARCH_64:
> case R_LARCH_64_PCREL:
> return 8;
> default:
> ERROR("unknown LoongArch reloc type");
> }
> } else {
> return 8;
> }
> }
How about tools/objtool/arch/loongarch/decode.c? Then we don't need to
check e_machine.
--
Josh
On 11/27/2024 08:57 AM, Josh Poimboeuf wrote:
> On Tue, Nov 26, 2024 at 09:22:22PM +0800, Tiezhu Yang wrote:
>>> OK, if I understand your comment correctly, this should be an
>>> arch-specific function defined in
>>> tools/objtool/arch/*/include/arch/elf.h, otherwise it also needs to
>>> check ehdr.e_machine
>>> in tools/objtool/include/objtool/elf.h.
>>
>> There are only macro definitions in
>> tools/objtool/arch/*/include/arch/elf.h,
>> so I think it is better to add reloc_size() in
>> tools/objtool/include/objtool/elf.h,
>> like this:
>>
>> static inline unsigned int reloc_size(struct elf *elf, struct reloc *reloc)
>> {
>> if (elf->ehdr.e_machine == EM_X86_64) {
>> switch (reloc_type(reloc)) {
>> case R_X86_64_32:
>> case R_X86_64_PC32:
>> return 4;
>> case R_X86_64_64:
>> case R_X86_64_PC64:
>> return 8;
>> default:
>> ERROR("unknown X86_64 reloc type");
>> }
>> } else if (elf->ehdr.e_machine == EM_LOONGARCH) {
>> switch (reloc_type(reloc)) {
>> case R_LARCH_32:
>> case R_LARCH_32_PCREL:
>> return 4;
>> case R_LARCH_64:
>> case R_LARCH_64_PCREL:
>> return 8;
>> default:
>> ERROR("unknown LoongArch reloc type");
>> }
>> } else {
>> return 8;
>> }
>> }
>
> How about tools/objtool/arch/loongarch/decode.c? Then we don't need to
> check e_machine.
OK, makes sense, will do it.
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