selftests:x86: Fix Format String Warnings in lam.c

This commit addresses compiler warnings in lam.c related to the usage
of non-literal format strings without format arguments in the
'run_test' function.

Warnings fixed:
- Resolved warnings indicating that 'ksft_test_result_skip' and
'ksft_test_result' were called with 't->msg' as a format string without
accompanying format arguments.

Changes made:
- Modified the calls to 'ksft_test_result_skip' and 'ksft_test_result'
to explicitly include a format specifier ("%s") for 't->msg'.
- This ensures that the string is safely treated as a format argument,
adhering to safer coding practices and resolving the compiler warnings.

Signed-off-by: angquan yu <angquan21@gmail.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests/x86/lam: Zero out buffer for readlink()

Zero out the buffer for readlink() since readlink() does not append a
terminating null byte to the buffer. Also change the buffer length
passed to readlink() to 'PATH_MAX - 1' to ensure the resulting string
is always null terminated.

Fixes: 833c12ce0f430 ("selftests/x86/lam: Add inherit test cases for linear-address masking")
Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Link: https://lore.kernel.org/r/20231016062446.695-1-binbin.wu@linux.intel.com

selftests/x86/lam: Add test cases for LAM vs thread creation

LAM enabling is only allowed when the process has single thread.
LAM mode is inherited into child thread.

Trying to enable LAM after spawning a thread has to fail.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20230312112612.31869-18-kirill.shutemov%40linux.intel.com

selftests/x86/lam: Add ARCH_FORCE_TAGGED_SVA test cases for linear-address masking

By default do not allow to enable both LAM and use SVA in the same
process.
The new ARCH_FORCE_TAGGED_SVA arch_prctl() overrides the limitation.

Add new test cases for the new arch_prctl:
Before using ARCH_FORCE_TAGGED_SVA, should not allow to enable LAM/SVA
coexisting. the test cases should be negative.

The test depands on idxd driver and iommu. before test, need add
"intel_iommu=on,sm_on" in kernel command line and insmod idxd driver.

Signed-off-by: Weihong Zhang <weihong.zhang@intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20230312112612.31869-17-kirill.shutemov%40linux.intel.com

selftests/x86/lam: Add inherit test cases for linear-address masking

LAM is enabled per-thread and gets inherited on fork(2)/clone(2). exec()
reverts LAM status to the default disabled state.

There are two test scenarios:

- Fork test cases:

These cases were used to test the inheritance of LAM for per-thread,
Child process generated by fork() should inherit LAM feature from
parent process, Child process can get the LAM mode same as parent
process.

- Execve test cases:

Processes generated by execve() are different from processes
generated by fork(), these processes revert LAM status to disabled
status.

Signed-off-by: Weihong Zhang <weihong.zhang@intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20230312112612.31869-16-kirill.shutemov%40linux.intel.com

selftests/x86/lam: Add io_uring test cases for linear-address masking

LAM should be supported in kernel thread, using io_uring to verify LAM feature.
The test cases implement read a file through io_uring, the test cases choose an
iovec array as receiving buffer, which used to receive data, according to LAM
mode, set metadata in high bits of these buffer.

io_uring can deal with these buffers that pointed to pointers with the metadata
in high bits.

Signed-off-by: Weihong Zhang <weihong.zhang@intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20230312112612.31869-15-kirill.shutemov%40linux.intel.com

selftests/x86/lam: Add mmap and SYSCALL test cases for linear-address masking

Add mmap and SYSCALL test cases.

SYSCALL test cases:

- LAM supports set metadata in high bits 62:57 (LAM_U57) of a user pointer, pass
the pointer to SYSCALL, SYSCALL can dereference the pointer and return correct
result.

- Disable LAM, pass a pointer with metadata in high bits to SYSCALL,
SYSCALL returns -1 (EFAULT).

MMAP test cases:

- Enable LAM_U57, MMAP with low address (below bits 47), set metadata
in high bits of the address, dereference the address should be
allowed.

- Enable LAM_U57, MMAP with high address (above bits 47), set metadata
in high bits of the address, dereference the address should be
allowed.

Signed-off-by: Weihong Zhang <weihong.zhang@intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20230312112612.31869-14-kirill.shutemov%40linux.intel.com

selftests/x86/lam: Add malloc and tag-bits test cases for linear-address masking

LAM is supported only in 64-bit mode and applies only addresses used for data
accesses. In 64-bit mode, linear address have 64 bits. LAM is applied to 64-bit
linear address and allow software to use high bits for metadata.
LAM supports configurations that differ regarding which pointer bits are masked
and can be used for metadata.

LAM includes following mode:

- LAM_U57, pointer bits in positions 62:57 are masked (LAM width 6),
allows bits 62:57 of a user pointer to be used as metadata.

There are some arch_prctls:
ARCH_ENABLE_TAGGED_ADDR: enable LAM mode, mask high bits of a user pointer.
ARCH_GET_UNTAG_MASK: get current untagged mask.
ARCH_GET_MAX_TAG_BITS: the maximum tag bits user can request. zero if LAM
is not supported.

The LAM mode is for pre-process, a process has only one chance to set LAM mode.
But there is no API to disable LAM mode. So all of test cases are run under
child process.

Functions of this test:

MALLOC

- LAM_U57 masks bits 57:62 of a user pointer. Process on user space
can dereference such pointers.

- Disable LAM, dereference a pointer with metadata above 48 bit or 57 bit
lead to trigger SIGSEGV.

TAG_BITS

- Max tag bits of LAM_U57 is 6.

Signed-off-by: Weihong Zhang <weihong.zhang@intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20230312112612.31869-13-kirill.shutemov%40linux.intel.com