linux.git/tools/testing/selftests/livepatch/test-syscall.sh, branch v6.18.21

selftests: livepatch: save and restore kprobe state

2024-10-22T15:13:11+00:00

Save the state of /sys/kernel/debug/kprobes/enabled
during setup_config() and restore it during cleanup().

This is in preparation for a future commit that will add a test
that should confirm that we cannot livepatch a kprobed function
if that kprobe has a post handler.

Signed-off-by: Michael Vetter 
Reviewed-by: Miroslav Benes 
Reviewed-by: Joe Lawrence 
Tested-by: Marcos Paulo de Souza 
Reviewed-by: Marcos Paulo de Souza 
Reviewed-by: Petr Mladek 
Tested-by: Petr Mladek 
Link: https://lore.kernel.org/r/20241017200132.21946-3-mvetter@suse.com
[pmladek@suse.com: Added few more substitutions in test-syscall.sh]
Signed-off-by: Petr Mladek

selftests: livepatch: rename KLP_SYSFS_DIR to SYSFS_KLP_DIR

2024-10-22T15:12:46+00:00

This naming makes more sense according to the directory structure.
Especially when we later add more paths.

Addtionally replace `/sys/kernel/livepatch` with `$SYSFS_KLP_DIR` in
the livepatch test files.

Signed-off-by: Michael Vetter 
Reviewed-by: Miroslav Benes 
Reviewed-by: Joe Lawrence 
Tested-by: Marcos Paulo de Souza 
Reviewed-by: Marcos Paulo de Souza 
Reviewed-by: Petr Mladek 
Tested-by: Petr Mladek 
Link: https://lore.kernel.org/r/20241017200132.21946-2-mvetter@suse.com
[pmladek@suse.com: Fix corrupted substitution]
Signed-off-by: Petr Mladek

selftests/livepatch: define max test-syscall processes

2024-06-12T14:56:30+00:00

Define a maximum allowable number of pids that can be livepatched in
test-syscall.sh as with extremely large machines the output from a
large number of processes overflows the dev/kmsg "expect" buffer in
the "check_result" function and causes a false error.

Reported-by: CKI Project 
Signed-off-by: Ryan Sullivan 
Acked-by: Miroslav Benes 
Tested-by: Marcos Paulo de Souza 
Reviewed-by: Marcos Paulo de Souza 
Reviewed-by: Petr Mladek 
Acked-by: Joel Savitz 
Link: https://lore.kernel.org/r/20240606135348.4708-1-rysulliv@redhat.com
Signed-off-by: Petr Mladek

selftests: livepatch: Test livepatching a heavily called syscall

2024-01-22T17:29:53+00:00

The test proves that a syscall can be livepatched. It is interesting
because syscalls are called a tricky way. Also the process gets
livepatched either when sleeping in the userspace or when entering
or leaving the kernel space.

The livepatch is a bit tricky:
  1. The syscall function name is architecture specific. Also
     ARCH_HAS_SYSCALL_WRAPPER must be taken in account.

  2. The syscall must stay working the same way for other processes
     on the system. It is solved by decrementing a counter only
     for PIDs of the test processes. It means that the test processes
     has to call the livepatched syscall at least once.

The test creates one userspace process per online cpu. The processes
are calling getpid in a busy loop. The intention is to create random
locations when the livepatch gets enabled. Nothing is guarantted.
The magic is in the randomness.

Reviewed-by: Joe Lawrence 
Reviewed-by: Petr Mladek 
Signed-off-by: Marcos Paulo de Souza 
Signed-off-by: Shuah Khan