Kernel livepatching modules build on GCC 10, with patched functions
referring to local function would fail to load with the error:
module_64: livepatch_ext4_cond_resched: Expected nop after call, got 7fe5fb78 at ext4_setup_system_zone+0x460/0xc90 [livepatch_ext4_cond_resched]
for more details on the error, refer to discussion at:
https://lkml.kernel.org/r/1508217523-18885-1-git-send-email-kamalesh@linux.vnet.ibm.com
the reason was that the gcc-plugin would skip the pass on error, failing
to convert the local calls into global, i.e on ppc64le every global call
is followed by a nop instruction, that gets replaced by the kernel to
restore
the TOC/r2 value of the callee, while parsing the relocations and would
skip the TOC restoration for local functions, where the TOC remains the
same across sibling functions.
GCC 10 commit 07c48b61a082("[RS6000] Put call cookie back in AIX/ELFv2
call patterns") merged a couple of call codes definition, breaking the
plugin. Change the plugin codes to match the GCC 10 codes.
Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Abort building the klp module, if the code for local and non-local calls
are not found instead of skipping the pass and building module, which
might result in un-loadable module with the kernel error:
module_64: livepatch_ext4_cond_resched: Expected nop after call, got 7fe5fb78 at ext4_setup_system_zone+0x460/0xc90 [livepatch_ext4_cond_resched]
gcc would not allow me to use "can't" in the error message and throw
build error:
gcc-plugins/ppc64le-plugin.c:49:17: error: contraction ‘can't’ in format; use ‘cannot’ instead [-Werror=format-diag]
Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Building on Fedora 32 with GCC 10.1.1, triggers build failures:
In file included from gcc-plugins/ppc64le-plugin.c:1:
gcc-plugins/gcc-common.h:37:10: fatal error: params.h: No such file or directory
37 | #include "params.h"
| ^~~~~~~~~~
compilation terminated.
In file included from gcc-plugins/ppc64le-plugin.c:1:
gcc-plugins/gcc-common.h:841:13: error: redefinition of ‘static bool is_a_helper<T>::test(U*) [with U = const gimple; T = const ggoto*]’
841 | inline bool is_a_helper<const ggoto *>::test(const_gimple gs)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from gcc-plugins/gcc-common.h:124,
from gcc-plugins/ppc64le-plugin.c:1:
/usr/lib/gcc/ppc64le-redhat-linux/10/plugin/include/gimple.h:1037:1:
note: ‘static bool is_a_helper<T>::test(U*) [with U = const gimple; T = const ggoto*]’ previously declared here
1037 | is_a_helper <const ggoto *>::test (const gimple *gs)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from gcc-plugins/ppc64le-plugin.c:1:
gcc-plugins/gcc-common.h:848:13: error: redefinition of ‘static bool is_a_helper<T>::test(U*) [with U = const gimple; T = const greturn*]’
848 | inline bool is_a_helper<const greturn *>::test(const_gimple gs)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from gcc-plugins/gcc-common.h:124,
from gcc-plugins/ppc64le-plugin.c:1:
/usr/lib/gcc/ppc64le-redhat-linux/10/plugin/include/gimple.h:1489:1:
note: ‘static bool is_a_helper<T>::test(U*) [with U = const gimple; T = const greturn*]’ previously declared here
1489 | is_a_helper <const greturn *>::test (const gimple *gs)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
as per kernel commit c7527373fe28 ("gcc-common.h: Update for GCC 10")
"params.h header file has been dropped from GCC 10 and is_a_helper()
macro is now defined in gimple.h"
this patch fix them by guarding the both param.h header file and
is_a_helper() with #ifdef checking for gcc version < 10000.
Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
plugin compilation fails on GCC 8:
In file included from gcc-plugins/gcc-common.h:100,
from gcc-plugins/ppc64le-plugin.c:1:
/usr/lib/gcc/powerpc64le-linux-gnu/8/plugin/include/attribs.h: In function ‘tree_node* canonicalize_attr_name(tree)’:
/usr/lib/gcc/powerpc64le-linux-gnu/8/plugin/include/attribs.h:118:11: error: ‘get_identifier_with_length’ was not declared in this scope
return get_identifier_with_length (s + 2, l - 4);
^~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/lib/gcc/powerpc64le-linux-gnu/8/plugin/include/attribs.h:118:11: note: suggested alternative: ‘get_attr_min_length’
return get_identifier_with_length (s + 2, l - 4);
^~~~~~~~~~~~~~~~~~~~~~~~~~
get_attr_min_length
Makefile:34: recipe for target 'gcc-plugins/ppc64le-plugin.so' failed
get_identifier_with_length() is defined under stringpool.h, include this
header file for GCC 8, before including attribs.h
Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
On ppc64le, building drivers/media/i2c/cx25840/cx25840.ko with GCC 4.85,
the plugin triggers the following errors:
{standard input}: Assembler messages:
{standard input}:1078: Error: operand out of range (0x0000000000008fd4 is not between 0xffffffffffff8000 and 0x0000000000007ffc)
{standard input}:1288: Error: operand out of range (0x000000000000874c is not between 0xffffffffffff8000 and 0x0000000000007ffc)
{standard input}:3844: Error: operand out of range (0x00000000000080e8 is not between 0xffffffffffff8000 and 0x0000000000007ffc)
{standard input}:4028: Error: operand out of range (0x00000000000082b4 is not between 0xffffffffffff8000 and 0x0000000000007ffc)
{standard input}:4031: Error: operand out of range (0x00000000000080b4 is not between 0xffffffffffff8000 and 0x0000000000007ffc)
{standard input}:6661: Error: operand out of range (0x000000000000841c is not between 0xffffffffffff8000 and 0x0000000000007ffc)
{standard input}:6664: Error: operand out of range (0x0000000000008214 is not between 0xffffffffffff8000 and 0x0000000000007ffc)
{standard input}:6845: Error: operand out of range (0x00000000000089dc is not between 0xffffffffffff8000 and 0x0000000000007ffc)
{standard input}:6848: Error: operand out of range (0x00000000000087d4 is not between 0xffffffffffff8000 and 0x0000000000007ffc)
{standard input}:7587: Error: operand out of range (0x0000000000008930 is not between 0xffffffffffff8000 and 0x0000000000007ffc)
{standard input}:7590: Error: operand out of range (0x0000000000008728 is not between 0xffffffffffff8000 and 0x0000000000007ffc)
{standard input}:14592: Error: operand out of range (0xffffffffffff79b8 is not between 0xffffffffffff8000 and 0x0000000000007ffc)
make[1]: *** [drivers/media/i2c/cx25840/cx25840-core.o] Error 1
The problem is that the plugin nops were inserted too late. GCC laid
out the code with knowledge about the distance between branches, but
then the plugin came along after that and increased the branch distances
by inserting the nops.
Fix it by inserting the nops as early as possible. The 'vregs' pass is
where the insn codes get initialized, so run the plugin immediately
afterwards.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
This is in response to an upstream discussion for the following patch:
https://lkml.kernel.org/r/1508217523-18885-1-git-send-email-kamalesh@linux.vnet.ibm.com
This should hopefully make it a lot easier for the ppc64le kernel module
code to support klp relocations.
The gcc-common.h and gcc-generate-rtl-pass.h header files are copied
from the upstream Linux source tree.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Kamalesh Babulal
Josh Poimboeuf