The term "dynrela" was invented before klp relocations ever existed.
They're basically the same thing: special livepatch-specific relocations
which get applied when the patched object gets loaded or patched.
They're necessary due to a) the need to access unexported symbols; and
b) late module patching.
The different names are confusing. Consolidate them by replacing
"dynrela" with "klp_reloc" (code) or "klp relocation" (English).
Note there's still some antiquated code in the kpatch core module and in
the pre-4.7 klp patch template which still use the "dynrela" naming.
That code is mostly dead anyway so I've just left it alone.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
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 <jpoimboe@redhat.com>
In kpatch-build, there are a number of places where a dynamic allocation
is performed, but the allocation is not checked for a failure. The
common pattern in kpatch-build is to check whether the returned pointer
is NULL, and if so, invoke the ERROR() macro to print a message and
abort the program.
kpatch_create_mcount_sections(), CORRELATE_ELEMENT(), and
create_klp_arch_sections() all had dynamic allocations without failure
checks. This diff adjusts those callsites to properly check for a failed
allocation, and ERROR() accordingly.
Signed-off-by: David Vernet <void@manifault.com>
Currently all the callers of kpatch_write_output_elf() are creating
.o object files or .ko kernel modules. Neither of these filetypes are
executable on their own, so enhance kpatch_write_output_elf() to accept
file creation mode and update its callers to pass 0664 to match
the expected permissions.
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Make sure symtab section was found before dereferencing it.
Found by covscan, see issue #984 for full log.
Signed-off-by: Artem Savkov <asavkov@redhat.com>
Only user of "entries" variable was sizeof and the value was never
actually used. Use struct name directly instead.
Found by covscan, see issue #984 for full log.
Signed-off-by: Artem Savkov <asavkov@redhat.com>
reason: The strdup() function returns a pointer to a new string
which is a duplicate of the string s. Memory for the
new string is obtained with malloc, and can be freed
with free.
here, fix memleak by removing the strdup.
Signed-off-by: chenzefeng <chenzefeng2@huawei.com>
From Oracle's Linker and Libraries Guide [1]:
"The symbols in a symbol table are written in the following order ...
The global symbols immediately follow the local symbols in the symbol
table. The first global symbol is identified by the symbol table sh_info
value. Local and global symbols are always kept separate in this manner,
and cannot be mixed together."
[1] https://docs.oracle.com/cd/E19120-01/open.solaris/819-0690/chapter6-79797/index.htmlFixes#854.
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
- convert section/symbol indexes and rela->offset to unsigned int as I
couldn't find any way for them to become negative.
- cast a number of rela->addend comparisons to int (assuming an 64bit
system this should be enough)
- a number of simple for-loop counter conversions to the type it
compares against
Signed-off-by: Artem Savkov <asavkov@redhat.com>
When creating .kpatch.relocations, there's no reason to convert the
relocation destinations to symbols. In fact, it's actively harmful
because it makes it harder for create-klp-module to deal with the GCC 6+
8-byte localentry gap.
This also fixes a regression which was introduced in 5888f316e6, which
broke ppc64le relocations.
Fixes#754.
Fixes: 5888f316e6 ("create-klp-module: support unbundled symbols")
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
kpatch_relocation's 'dest' addend and 'offset' fields are redundant. In
fact, the 'offset' field isn't always accurate because it doesn't have a
relocation, so its value doesn't adjust when multiple .o files are
combined. Just use the 'dest' addend instead.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
kpatch_replace_sections_syms() assumes that all bundled symbols start at
section offset zero. With ppc64le and GCC 6+, that assumption is no
longer accurate. When replacing a rela symbol section with its
corresponding symbol, adjust the addend as necessary.
Also, with this fix in place, the workaround in
create_klp_relasecs_and_syms() can be removed.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Valgrind complains about an uninitialized variable in
create-klp-module.c:
==4412== Conditional jump or move depends on uninitialised value(s)
==4412== at 0x402846: main (create-klp-module.c:497)
This warning refers to main()'s struct arguments stack variable,
precisely its .no_klp_arch member. Initialize the entire structure to
zero to avoid complaint.
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
The create_klp_relasecs_and_syms() function assumes that all dest
symbols are bundled, i.e. each symbol is located at offset 0 in its own
section.
However that may not always be the case. Unbundled symbols can occur,
for example, when combining two .o files which have the same bundled
symbol. They will be combined into the same section and will no longer
be considered "bundled".
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
With gcc-6 the function prologue is changeg by
moving the toc base resolution func - 0x8 bytes:
.globl my_func
.type my_func, @function
.quad .TOC.-my_func
my_func:
.reloc ., R_PPC64_ENTRY ; optional
ld r2,-8(r12)
add r2,r2,r12
.localentry my_func, .-my_func
Add support for function prologue, along with gcc-5.
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
This patch adds support for livepatch hook based module
creation for PPC64le. It introduces PPC64le architecture
bits:
- Add relocation type of R_PPC64_ADDR64 while parsing powerpc ELF.
- Introduce .toc sections mainpulation.
- Skip kpatch specific details for livepatch hook.
Also remove the definition of rela_insn() for powerpc. The only
call site is been guarded by #ifdef x86.
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Add a new program, create-klp-module, that, given a built module (.ko),
will create a patch module with klp rela sections, klp arch sections, and
klp symbols.
Josh Poimboeuf
David Vernet
Joe Lawrence
Kamalesh Babulal
Artem Savkov
chenzefeng
Jessica Yu