This is a note to let you know that I've just added the patch titled
selftests/bpf: Fix fill_link_info selftest on powerpc
to the 6.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
selftests-bpf-fix-fill_link_info-selftest-on-powerpc.patch
and it can be found in the queue-6.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 99ba4bd94f10806a6324aa8b6aa7f1501dba8616
Author: Saket Kumar Bhaskar <skb99@xxxxxxxxxxxxx>
Date: Mon Dec 9 12:27:20 2024 +0530
selftests/bpf: Fix fill_link_info selftest on powerpc
[ Upstream commit 4d33dc1bc31df80356c49e40dbd3ddff19500bcb ]
With CONFIG_KPROBES_ON_FTRACE enabled on powerpc, ftrace_location_range
returns ftrace location for bpf_fentry_test1 at offset of 4 bytes from
function entry. This is because branch to _mcount function is at offset
of 4 bytes in function profile sequence.
To fix this, add entry_offset of 4 bytes while verifying the address for
kprobe entry address of bpf_fentry_test1 in verify_perf_link_info in
selftest, when CONFIG_KPROBES_ON_FTRACE is enabled.
Disassemble of bpf_fentry_test1:
c000000000e4b080 <bpf_fentry_test1>:
c000000000e4b080: a6 02 08 7c mflr r0
c000000000e4b084: b9 e2 22 4b bl c00000000007933c <_mcount>
c000000000e4b088: 01 00 63 38 addi r3,r3,1
c000000000e4b08c: b4 07 63 7c extsw r3,r3
c000000000e4b090: 20 00 80 4e blr
When CONFIG_PPC_FTRACE_OUT_OF_LINE [1] is enabled, these function profile
sequence is moved out of line with an unconditional branch at offset 0.
So, the test works without altering the offset for
'CONFIG_KPROBES_ON_FTRACE && CONFIG_PPC_FTRACE_OUT_OF_LINE' case.
Disassemble of bpf_fentry_test1:
c000000000f95190 <bpf_fentry_test1>:
c000000000f95190: 00 00 00 60 nop
c000000000f95194: 01 00 63 38 addi r3,r3,1
c000000000f95198: b4 07 63 7c extsw r3,r3
c000000000f9519c: 20 00 80 4e blr
[1] https://lore.kernel.org/all/20241030070850.1361304-13-hbathini@xxxxxxxxxxxxx/
Fixes: 23cf7aa539dc ("selftests/bpf: Add selftest for fill_link_info")
Signed-off-by: Saket Kumar Bhaskar <skb99@xxxxxxxxxxxxx>
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20241209065720.234344-1-skb99@xxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/tools/testing/selftests/bpf/prog_tests/fill_link_info.c b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
index d50cbd8040d45..e59af2aa66016 100644
--- a/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
+++ b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
@@ -171,6 +171,10 @@ static void test_kprobe_fill_link_info(struct test_fill_link_info *skel,
/* See also arch_adjust_kprobe_addr(). */
if (skel->kconfig->CONFIG_X86_KERNEL_IBT)
entry_offset = 4;
+ if (skel->kconfig->CONFIG_PPC64 &&
+ skel->kconfig->CONFIG_KPROBES_ON_FTRACE &&
+ !skel->kconfig->CONFIG_PPC_FTRACE_OUT_OF_LINE)
+ entry_offset = 4;
err = verify_perf_link_info(link_fd, type, kprobe_addr, 0, entry_offset);
ASSERT_OK(err, "verify_perf_link_info");
} else {
diff --git a/tools/testing/selftests/bpf/progs/test_fill_link_info.c b/tools/testing/selftests/bpf/progs/test_fill_link_info.c
index 6afa834756e9f..fac33a14f2009 100644
--- a/tools/testing/selftests/bpf/progs/test_fill_link_info.c
+++ b/tools/testing/selftests/bpf/progs/test_fill_link_info.c
@@ -6,13 +6,20 @@
#include <stdbool.h>
extern bool CONFIG_X86_KERNEL_IBT __kconfig __weak;
+extern bool CONFIG_PPC_FTRACE_OUT_OF_LINE __kconfig __weak;
+extern bool CONFIG_KPROBES_ON_FTRACE __kconfig __weak;
+extern bool CONFIG_PPC64 __kconfig __weak;
-/* This function is here to have CONFIG_X86_KERNEL_IBT
- * used and added to object BTF.
+/* This function is here to have CONFIG_X86_KERNEL_IBT,
+ * CONFIG_PPC_FTRACE_OUT_OF_LINE, CONFIG_KPROBES_ON_FTRACE,
+ * CONFIG_PPC6 used and added to object BTF.
*/
int unused(void)
{
- return CONFIG_X86_KERNEL_IBT ? 0 : 1;
+ return CONFIG_X86_KERNEL_IBT ||
+ CONFIG_PPC_FTRACE_OUT_OF_LINE ||
+ CONFIG_KPROBES_ON_FTRACE ||
+ CONFIG_PPC64 ? 0 : 1;
}
SEC("kprobe")
