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Fix addend handling and other cleanups for s390#1269

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jpoimboe merged 17 commits intodynup:masterfrom
jpoimboe:reloc-addend
May 19, 2022
Merged

Fix addend handling and other cleanups for s390#1269
jpoimboe merged 17 commits intodynup:masterfrom
jpoimboe:reloc-addend

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@jpoimboe jpoimboe commented May 12, 2022

Several improvements for issues discovered in the review for #1203 .Mostly related to addend handling, but also some other cleanups and an endianness fix.

jpoimboe added 13 commits May 11, 2022 13:55
@jpoimboe
kpatch-build: make xtrace output less verbose
0c5a1e7 
With '--debug', most of the xtrace output shows the reading of the
.config and Module.symvers files, which isn't very useful and floods the
rest of the xtrace output.  Temporarily disable xtrace before reading
the files.

Signed-off-by: Josh Poimboeuf <[email protected]>
@jpoimboe
kpatch-elf: convert functions to static
3b63456 
These functions are only called locally, convert them to static.

Signed-off-by: Josh Poimboeuf <[email protected]>
@jpoimboe
create-diff-object: rename "sec" -> "relasec" for rela sections
c24d135 
Several functions expect to take a ".rela" section as an argument.  Make
such cases more clear by renaming "sec" -> "relasec".

Signed-off-by: Josh Poimboeuf <[email protected]>
@jpoimboe
create-diff-object: convert function return types to 'bool'
61e4609 
Several functions have a boolean semantic, but don't actually return
bool, which is confusing.  Fix that.

Signed-off-by: Josh Poimboeuf <[email protected]>
@jpoimboe
create-diff-object: fix kpatch_replace_sections_syms() for non-text
79f45d1 
It doesn't make sense to disassemble a data section.  That just happened
to work by accident.  PC-relative offsets only need adjusting when
associated with an instruction.

Signed-off-by: Josh Poimboeuf <[email protected]>
@jpoimboe
create-diff-object: support R_X86_64_NONE in kpatch_replace_sections_…
3f8e106 
…syms()

Add support for R_X86_64_NONE.  With an upstream kernel, it's quite
rare, only used for a few jump labels.  With older kernels it was used
for fentry hooks.  Either way, it should be treated like a PC-relative
relocation.

Signed-off-by: Josh Poimboeuf <[email protected]>
@jpoimboe
create-diff-object: error on unsupported rela in symbol conversion
bf212f7 
Error out if an unsupported rela is encountered.  This is more robust
than just ignoring it.

Signed-off-by: Josh Poimboeuf <[email protected]>
@jpoimboe
create-diff-object: convert rela_insn() to take normal 'sec'
6b1895a 
rela_insn() only cares about the base section.  Convert it to take a
non-rela section as its argument instead of a relasec.

Signed-off-by: Josh Poimboeuf <[email protected]>
@jpoimboe
create-diff-object: add rela_insn() error check
bec6488 
Error out if the insn can't be found.

Signed-off-by: Josh Poimboeuf <[email protected]>
@jpoimboe
create-diff-object: move addend math to a new function
01427d5 
Split out the addend offset math into a separate function so it can be
used elsewhere.

Signed-off-by: Josh Poimboeuf <[email protected]>
@jpoimboe
create-diff-object: add extra check for symbol conversion edge case
8d5a628 
This issue was only seen in in a text section.  Explicitly check for
that.

Signed-off-by: Josh Poimboeuf <[email protected]>
@jpoimboe
create-diff-object: allow converstion of empty symbols
8508abd 
Empty (zero-length) symbols are possible, allow
kpatch_replace_sections_syms() to work on them.

Signed-off-by: Josh Poimboeuf <[email protected]>
@jpoimboe
create-diff-object: skip conversion for sections which never have sym…
325bccd 
…bols

These sections don't have symbols.  Don't even try to replace references
to them with symbols.

Signed-off-by: Josh Poimboeuf <[email protected]>
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joe-lawrence commented May 13, 2022

Hi @jpoimboe ,

Check out the internal automated integration test failure emails, there are various complaints like these:

create-diff-object: ERROR: af_netlink.o: kpatch_replace_sections_syms: 1609: .text.jhash+0x95: 
can't find replacement symbol for .rodata.jhash+0 reference

create-diff-object: ERROR: sys.o: kpatch_replace_sections_syms: 1609: .text.prctl_set_mm+0x1c7:
can't find replacement symbol for .rodata.prctl_set_mm+0 reference

create-diff-object: ERROR: fib_frontend.o: kpatch_replace_sections_syms: 1609: .text.rtm_to_fib_config+0x13a:
can't find replacement symbol for .rodata.rtm_to_fib_config+0 reference

create-diff-object: ERROR: array.o: kpatch_replace_sections_syms: 1609: .text.proc_pid_status+0x619:
can't find replacement symbol for .rodata.proc_pid_status+0 reference

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jpoimboe commented May 18, 2022

Going to squash in this change to fix the integration failures:

diff --git a/kpatch-build/create-diff-object.c b/kpatch-build/create-diff-object.c
index 8345b16..bebe3bd 100644
--- a/kpatch-build/create-diff-object.c
+++ b/kpatch-build/create-diff-object.c
@@ -1604,7 +1604,7 @@ static void kpatch_replace_sections_syms(struct kpatch_elf *kelf)
                        }
 
                        if (!found && !is_string_literal_section(rela->sym->sec) &&
-                           strcmp(rela->sym->name, ".rodata")) {
+                           strncmp(rela->sym->name, ".rodata", 7)) {
                                ERROR("%s+0x%x: can't find replacement symbol for %s+%ld reference",
                                      relasec->base->name, rela->offset, rela->sym->name, rela->addend);
                        }

jpoimboe added 4 commits May 17, 2022 19:27
@jpoimboe
create-diff-object: error on symbol conversion failure
86d5208 
If a section reference can't be converted to a symbol reference, error
out to try to prevent unexpected behavior later on.

There are a few sections for which a symbol is optional: .rodata and
string literal sections.  Don't warn about those.

Signed-off-by: Josh Poimboeuf <[email protected]>
@jpoimboe
create-diff-object: fix string extraction
f0e3da3 
The current string extraction is broken for non-section symbols.  Fix
that.

Signed-off-by: Josh Poimboeuf <[email protected]>
@jpoimboe
create-diff-object: make kpatch_check_relocations() more precise
017015a 
Use rela_target_offset() to make the relocation bounds checking more
precise.

Signed-off-by: Josh Poimboeuf <[email protected]>
@jpoimboe
create-diff-object: fix endianness in kpatch_no_sibling_calls_ppc64le()
52863da 
Otherwise it fails the unit tests on an s390 host.

Signed-off-by: Josh Poimboeuf <[email protected]>
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jpoimboe commented May 18, 2022

v2:

  • refine .rodata check in missing replacement symbol warning

@jpoimboe jpoimboe merged commit f6e1838 into dynup:master May 19, 2022
@jpoimboe jpoimboe mentioned this pull request May 19, 2022
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