kernel/arch/s390/include/asm/stacktrace.h, branch linux-5.14.y

s390/unwind: use current_frame_address() to unwind current task

2021-09-26T12:10:22Z

[ Upstream commit 88b604263f3d6eedae0b1c2c3bbd602d1e2e8775 ] current_stack_pointer() simply returns current value of %r15. If current_stack_pointer() caller allocates stack (which is the case in unwind code) %r15 points to a stack frame allocated for callees, meaning current_stack_pointer() caller (e.g. stack_trace_save) will end up in the stacktrace. This is not expected by stack_trace_save*() callers and causes problems. current_frame_address() on the other hand returns function stack frame address, which matches %r15 upon function invocation. Using it in get_stack_pointer() makes it more aligned with x86 implementation (according to BACKTRACE_SELF_TEST output) and meets stack_trace_save*() caller's expectations, notably KCSAN. Also make sure unwind_start is always inlined. Reported-by: Nathan Chancellor Suggested-by: Marco Elver Signed-off-by: Vasily Gorbik Tested-by: Marco Elver Tested-by: Nathan Chancellor Link: https://lore.kernel.org/r/patch.git-04dd26be3043.your-ad-here.call-01630504868-ext-6188@work.hours Signed-off-by: Heiko Carstens Signed-off-by: Sasha Levin

s390: rename CALL_ON_STACK_NORETURN() to call_on_stack_noreturn()

2021-07-08T20:12:18Z

Lower case matches the call_on_stack() macro and is easier to read. Reviewed-by: Sven Schnelle Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390: add type checking to CALL_ON_STACK_NORETURN() macro

2021-07-08T20:12:18Z

Make sure the to be called function takes no arguments (and returns void). Otherwise usage of CALL_ON_STACK_NORETURN() would generate broken code. Reviewed-by: Sven Schnelle Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390: remove old CALL_ON_STACK() macro

2021-07-08T20:12:18Z

Reviewed-by: Sven Schnelle Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390: introduce proper type handling call_on_stack() macro

2021-07-08T20:12:17Z

The existing CALL_ON_STACK() macro allows for subtle bugs: - There is no type checking of the function that is being called. That is: missing or too many arguments do not cause any compile error or warning. The same is true if the return type of the called function changes. This can lead to quite random bugs. - Sign and zero extension of arguments is missing. Given that the s390 C ABI requires that the caller of a function performs proper sign and zero extension this can also lead to subtle bugs. - If arguments to the CALL_ON_STACK() macros contain functions calls register corruption can happen due to register asm constructs being used. Therefore introduce a new call_on_stack() macro which is supposed to fix all these problems. Reviewed-by: Sven Schnelle Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/stack: fix possible register corruption with stack switch helper

2021-06-21T09:19:18Z

The CALL_ON_STACK macro is used to call a C function from inline assembly, and therefore must consider the C ABI, which says that only registers 6-13, and 15 are non-volatile (restored by the called function). The inline assembly incorrectly marks all registers used to pass parameters to the called function as read-only input operands, instead of operands that are read and written to. This might result in register corruption depending on usage, compiler, and compile options. Fix this by marking all operands used to pass parameters as read/write operands. To keep the code simple even register 6, if used, is marked as read-write operand. Fixes: ff340d2472ec ("s390: add stack switch helper") Cc: # 4.20 Reviewed-by: Vasily Gorbik Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/unwind: add machine check handler stack

2021-04-05T09:30:07Z

Fixes: b61b1595124a ("s390: add stack for machine check handler") Signed-off-by: Vasily Gorbik Signed-off-by: Heiko Carstens

s390: fix register clobbering in CALL_ON_STACK

2019-11-30T09:52:47Z

CALL_ON_STACK defines and initializes register variables. Inline assembly which follows might trigger compiler to generate memory access for "stack" argument (e.g. in case of S390_lowcore.nodat_stack). This memory access produces a function call under kasan with outline instrumentation which clobbers registers. Switch "stack" argument in CALL_ON_STACK helper to use memory reference constraint and perform load instead. Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/unwind: always inline get_stack_pointer

2019-11-30T09:52:46Z

Always inline get_stack_pointer() to avoid potential problems due to compiler inlining decisions, i.e. getting stack pointer of get_stack_pointer() itself which is later reused. Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390: avoid misusing CALL_ON_STACK for task stack setup

2019-11-30T09:52:45Z

CALL_ON_STACK is intended to be used for temporary stack switching with potential return to the caller. When CALL_ON_STACK is misused to switch from nodat stack to task stack back_chain information would later lead stack unwinder from task stack into (per cpu) nodat stack which is reused for other purposes. This would yield confusing unwinding result or errors. To avoid that introduce CALL_ON_STACK_NORETURN to be used instead. It makes sure that back_chain is zeroed and unwinder finishes gracefully ending up at task pt_regs. Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik