kernel/linux.git/arch/s390/include/asm/stacktrace.h, branch v6.12.80

s390/entry: Pass the asce as parameter to sie64a()

2024-07-10T17:50:45+00:00

Pass the guest ASCE explicitly as parameter, instead of having sie64a() take it from lowcore. This removes hidden state from lowcore, and makes things look cleaner. Signed-off-by: Claudio Imbrenda Reviewed-by: Nico Boehr Link: https://lore.kernel.org/r/20240703155900.103783-2-imbrenda@linux.ibm.com Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/vdso: Introduce and use struct stack_frame_vdso_wrapper

2024-05-14T11:37:07+00:00

Introduce and use struct stack_frame_vdso_wrapper within vdso user wrapper code. With this structure it is possible to automatically generate an asm-offset define which can be used to save and restore the return address of the calling function. Also use STACK_FRAME_USER_OVERHEAD instead of STACK_FRAME_OVERHEAD to document that the code works with user space stack frames with the standard stack frame layout. Fixes: aa44433ac4ee ("s390: add USER_STACKTRACE support") Reviewed-by: Jens Remus Signed-off-by: Heiko Carstens Signed-off-by: Alexander Gordeev

s390/stacktrace: Merge perf_callchain_user() and arch_stack_walk_user()

2024-05-14T11:37:06+00:00

The two functions perf_callchain_user() and arch_stack_walk_user() are nearly identical. Reduce code duplication and add a common helper which can be called by both functions. Fixes: aa44433ac4ee ("s390: add USER_STACKTRACE support") Reviewed-by: Jens Remus Signed-off-by: Heiko Carstens Signed-off-by: Alexander Gordeev

s390/switch_to: use generic header file

2024-02-12T14:03:33+00:00

Move the switch_to() implementation to process.c and use the generic switch_to.h header file instead, like some other architectures. This addresses also the oddity that the old switch_to() implementation assigns the return value of __switch_to() to 'prev' instead of 'last', like it should. Remove also all includes of switch_to.h from C files, except process.c. Acked-by: Alexander Gordeev Signed-off-by: Heiko Carstens

s390/perf: implement perf_callchain_user()

2023-11-05T21:34:57+00:00

Daan De Meyer and Neal Gompa reported that s390 does not support perf user stack unwinding. This was never implemented since this requires user space to be compiled with the -mbackchain compile option, which until now no distribution did. However this is going to change with Fedora. Therefore provide a perf_callchain_user() implementation. Note that due to the way s390 sets up stack frames the provided call chains can contain invalid values. This is especially true for the first stack frame, where it is not possible to tell if the return address has been written to the stack already or not. Reported-by: Daan De Meyer Reported-by: Neal Gompa Closes: https://lore.kernel.org/all/CAO8sHcn3+_qrnvp0580aK7jN0Wion5F7KYeBAa4MnCY4mqABPA@mail.gmail.com/ Link: https://lore.kernel.org/all/20231030123558.10816-A-hca@linux.ibm.com Reviewed-by: Neal Gompa Acked-by: Ilya Leoshkevich Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/kdump: remove nodat stack restriction for calling nodat functions

2023-04-19T15:24:16+00:00

To allow calling of DAT-off code from kernel the stack needs to be switched to nodat_stack (or other stack mapped as 1:1). Before call_nodat() macro was introduced that was necessary to provide the very same memory address for STNSM and STOSM instructions. If the kernel would stay on a random stack (e.g. a virtually mapped one) then a virtual address provided for STNSM instruction could differ from the physical address needed for the corresponding STOSM instruction. After call_nodat() macro is introduced the kernel stack does not need to be mapped 1:1 anymore, since the macro stores the physical memory address of return PSW in a register before entering DAT-off mode. This way the return LPSWE instruction is able to pick the correct memory location and restore the DAT-on mode. That however might fail in case the 16-byte return PSW happened to cross page boundary: PSW mask and PSW address could end up in two separate non-contiguous physical pages. Align the return PSW on 16-byte boundary so it always fits into a single physical page. As result any stack (including the virtually mapped one) could be used for calling DAT-off code and prior switching to nodat_stack becomes unnecessary. Signed-off-by: Alexander Gordeev Reviewed-by: Heiko Carstens Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/kdump: rework invocation of DAT-off code

2023-04-19T15:24:16+00:00

Calling kdump kernel is a two-step process that involves invocation of the purgatory code: first time - to verify the new kernel checksum and second time - to call the new kernel itself. The purgatory code operates on real addresses and does not expect any memory protection. Therefore, before the purgatory code is entered the DAT mode is always turned off. However, it is only restored upon return from the new kernel checksum verification. In case the purgatory was called to start the new kernel and failed the control is returned to the old kernel, but the DAT mode continues staying off. The new kernel start failure is unlikely and leads to the disabled wait state anyway. Still that poses a risk, since the kernel code in general is not DAT-off safe and even calling the disabled_wait() function might crash. Introduce call_nodat() macro that allows entering DAT-off mode, calling an arbitrary function and restoring DAT mode back on. Switch all invocations of DAT-off code to that macro and avoid the above described scenario altogether. Name the call_nodat() macro in small letters after the already existing call_on_stack() and put it to the same header file. Signed-off-by: Alexander Gordeev Reviewed-by: Heiko Carstens [hca@linux.ibm.com: some small modifications to call_nodat() macro] Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/stacktrace: remove call_on_stack_noreturn()

2023-04-04T16:34:56+00:00

There is no user left of call_on_stack_noreturn() - remove it. Reviewed-by: Vasily Gorbik Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/entry: sort out physical vs virtual pointers usage in sie64a

2022-10-26T12:27:41+00:00

Fix virtual vs physical address confusion (which currently are the same). sie_block is accessed in entry.S and passed it to hardware, which is why both its physical and virtual address are needed. To avoid every caller having to do the virtual-physical conversion, add a new function sie64a() which converts the virtual address to physical. Signed-off-by: Nico Boehr Reviewed-by: Alexander Gordeev Reviewed-by: Claudio Imbrenda Link: https://lore.kernel.org/r/20221020143159.294605-3-nrb@linux.ibm.com Message-Id: <20221020143159.294605-3-nrb@linux.ibm.com> Signed-off-by: Janosch Frank

s390/stack: add union to reflect kvm stack slot usages

2022-06-01T10:03:17+00:00

Add a union which describes how the empty stack slots are being used by kvm and perf. This should help to avoid another bug like the one which was fixed with commit c9bfb460c3e4 ("s390/perf: obtain sie_block from the right address"). Reviewed-by: Nico Boehr Tested-by: Nico Boehr Signed-off-by: Heiko Carstens