kernel.git/arch/s390/Makefile, branch linux-4.16.y

s390: add automatic detection of the spectre defense

2018-05-25T14:46:06Z

[ Upstream commit 6e179d64126b909f0b288fa63cdbf07c531e9b1d ] Automatically decide between nobp vs. expolines if the spectre_v2=auto kernel parameter is specified or CONFIG_EXPOLINE_AUTO=y is set. The decision made at boot time due to CONFIG_EXPOLINE_AUTO=y being set can be overruled with the nobp, nospec and spectre_v2 kernel parameters. Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman

s390: introduce execute-trampolines for branches

2018-02-07T14:57:02Z

Add CONFIG_EXPOLINE to enable the use of the new -mindirect-branch= and -mfunction_return= compiler options to create a kernel fortified against the specte v2 attack. With CONFIG_EXPOLINE=y all indirect branches will be issued with an execute type instruction. For z10 or newer the EXRL instruction will be used, for older machines the EX instruction. The typical indirect call basr %r14,%r1 is replaced with a PC relative call to a new thunk brasl %r14,__s390x_indirect_jump_r1 The thunk contains the EXRL/EX instruction to the indirect branch __s390x_indirect_jump_r1: exrl 0,0f j . 0: br %r1 The detour via the execute type instruction has a performance impact. To get rid of the detour the new kernel parameter "nospectre_v2" and "spectre_v2=[on,off,auto]" can be used. If the parameter is specified the kernel and module code will be patched at runtime. Signed-off-by: Martin Schwidefsky

s390/tools: generate header files in arch/s390/include/generated/

2018-01-23T06:36:53Z

Previously, the generated dis.h and facilities.h header files have been stored in include/generated. Because they are s390 specific, store them in the arch/s390/include/generated/asm/ directory. Also update references to the header files respectively. To prevent name collisions with those header files in asm/ that include the generated ones, rename the generated headers files and add an -defs suffix. Also update the generators to create the ifdef guards respectively. Signed-off-by: Hendrik Brueckner Acked-by: Heiko Carstens Signed-off-by: Martin Schwidefsky

s390/syscalls: add Makefile to generate system call header files

2018-01-23T06:36:51Z

Generate the system call specific files from the archheaders and archprepare make targets. Signed-off-by: Hendrik Brueckner Acked-by: Heiko Carstens Signed-off-by: Martin Schwidefsky

s390/vdso: revise CFI annotations of vDSO functions

2017-12-13T09:51:36Z

Revise and add CFI CFA and register rule annotations to the vDSO functions for proper stack unwinding and debugging. Because glibc might call the vDSO in special ways, the vDSO code does not rely on a stack frame created by the caller. The TOD clock value can be therefore not stored in the pre-allocated stack area and additional stack space is required. To correctly annotate these situations with CFI, the .cfi_val_offset directive is required to create relative offsets on the value of the stack register %r15. Because the .cfi_val_offset directive is available with recent GNU assembler versions only, additional checks are necessary. Note that if the vDSO is assembled with an older assembler version, stack unwinding and debugging from within the vDSO code might not be possible. Signed-off-by: Hendrik Brueckner Reviewed-by: Heiko Carstens Signed-off-by: Martin Schwidefsky

s390/kernel: emit CFI data in .debug_frame and discard .eh_frame sections

2017-12-13T09:51:35Z

Using perf probe and libdw on kernel modules failed to find CFI data for symbols. The CFI data is stored in the .eh_frame section. The elfutils libdw is not able to extract the CFI data correctly, because the .eh_frame section requires "non-simple" relocations for kernel modules. The suggestion is to avoid these "non-simple" relocations by emitting the CFI data in the .debug_frame section. Let gcc emit respective directives by specifying the -fno-asynchronous-unwind-tables option. Using the .debug_frame section for CFI data, the .eh_frame section becomes unused and, thus, discard it for kernel and modules builds The vDSO requires the .eh_frame section and, hence, emit the CFI data in both, the .eh_frame and .debug_frame sections. See also discussion on elfutils/libdw bugzilla: https://sourceware.org/bugzilla/show_bug.cgi?id=22452 Suggested-by: Mark Wielaard Signed-off-by: Hendrik Brueckner Reviewed-by: Heiko Carstens Signed-off-by: Martin Schwidefsky

s390: Remove redundant license text

2017-11-24T14:37:24Z

Now that the SPDX tag is in all arch/s390/ files, that identifies the license in a specific and legally-defined manner. So the extra GPL text wording in the remaining files can be removed as it is no longer needed at all. This is done on a quest to remove the 700+ different ways that files in the kernel describe the GPL license text. And there's unneeded stuff like the address (sometimes incorrect) for the FSF which is never needed. No copyright headers or other non-license-description text was removed. Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: "Paul E. McKenney" Signed-off-by: Greg Kroah-Hartman Signed-off-by: Martin Schwidefsky

s390: add SPDX identifiers to the remaining files

2017-11-24T14:37:19Z

It's good to have SPDX identifiers in all files to make it easier to audit the kernel tree for correct licenses. Update the remaining arch/s390/ files with the correct SPDX license identifier based on the license text in the file itself. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This work is based on a script and data from Thomas Gleixner, Philippe Ombredanne, and Kate Stewart. Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: Christian Borntraeger Cc: Cornelia Huck Cc: Thomas Gleixner Cc: Kate Stewart Cc: Philippe Ombredanne Signed-off-by: Greg Kroah-Hartman Signed-off-by: Martin Schwidefsky

s390/disassembler: generate opcode tables from text file

2017-11-08T21:11:02Z

The current way of adding new instructions to the opcode tables is painful and error prone. Therefore add, similar to binutils, a text file which contains all opcodes and the corresponding mnemonics and instruction formats. A small gen_opcode_table tool then generates a header file with the required enums and opcode table initializers at the prepare step of the kernel build. This way only a simple text file has to be maintained, which can be rather easily extended. Unlike before where there were plenty of opcode tables and a large switch statement to find the correct opcode table, there is now only one opcode table left which contains all instructions. A second opcode offset table now contains offsets within the opcode table to find instructions which have the same opcode prefix. In order to save space all 1-byte opcode instructions are grouped together at the end of the opcode table. This is also quite similar to like it was before. In addition also move and change code and definitions within the disassembler. As a side effect this reduces the size required for the code and opcode tables by ~1.5k. Signed-off-by: Heiko Carstens

s390: pass endianness info to sparse

2017-11-02T06:52:25Z

s390 is big-endian only but sparse assumes the same endianness as the building machine. This is problematic for code which expect __BYTE_ORDER__ being correctly predefined by the compiler which sparse can then pre-process differently from what gcc would, depending on the building machine endianness. Fix this by letting sparse know about the architecture endianness. Signed-off-by: Luc Van Oostenryck Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky