kernel.git/arch/s390/kernel/module.c, branch linux-4.14.y

s390: correct module section names for expoline code revert

2018-04-29T09:33:16Z

[ Upstream commit 6cf09958f32b9667bb3ebadf74367c791112771b ] The main linker script vmlinux.lds.S for the kernel image merges the expoline code patch tables into two section ".nospec_call_table" and ".nospec_return_table". This is *not* done for the modules, there the sections retain their original names as generated by gcc: ".s390_indirect_call", ".s390_return_mem" and ".s390_return_reg". The module_finalize code has to check for the compiler generated section names, otherwise no code patching is done. This slows down the module code in case of "spectre_v2=off". Cc: stable@vger.kernel.org # 4.16 Fixes: f19fbd5ed6 ("s390: introduce execute-trampolines for branches") Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman

s390: add automatic detection of the spectre defense

2018-04-29T09:33:15Z

[ 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

2018-04-29T09:33:15Z

[ Upstream commit f19fbd5ed642dc31c809596412dab1ed56f2f156 ] 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 Signed-off-by: Greg Kroah-Hartman

s390: enable CPU alternatives unconditionally

2018-04-29T09:33:14Z

[ Upstream commit 049a2c2d486e8cc82c5cd79fa479c5b105b109e9 ] Remove the CPU_ALTERNATIVES config option and enable the code unconditionally. The config option was only added to avoid a conflict with the named saved segment support. Since that code is gone there is no reason to keep the CPU_ALTERNATIVES config option. Just enable it unconditionally to also reduce the number of config options and make it less likely that something breaks. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman

s390: introduce CPU alternatives

2018-04-29T09:33:14Z

[ Upstream commit 686140a1a9c41d85a4212a1c26d671139b76404b ] Implement CPU alternatives, which allows to optionally patch newer instructions at runtime, based on CPU facilities availability. A new kernel boot parameter "noaltinstr" disables patching. Current implementation is derived from x86 alternatives. Although ideal instructions padding (when altinstr is longer then oldinstr) is added at compile time, and no oldinstr nops optimization has to be done at runtime. Also couple of compile time sanity checks are done: 1. oldinstr and altinstr must be <= 254 bytes long, 2. oldinstr and altinstr must not have an odd length. alternative(oldinstr, altinstr, facility); alternative_2(oldinstr, altinstr1, facility1, altinstr2, facility2); Both compile time and runtime padding consists of either 6/4/2 bytes nop or a jump (brcl) + 2 bytes nop filler if padding is longer then 6 bytes. .altinstructions and .altinstr_replacement sections are part of __init_begin : __init_end region and are freed after initialization. Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman

s390: add no-execute support

2017-02-08T13:13:25Z

Bit 0x100 of a page table, segment table of region table entry can be used to disallow code execution for the virtual addresses associated with the entry. There is one tricky bit, the system call to return from a signal is part of the signal frame written to the user stack. With a non-executable stack this would stop working. To avoid breaking things the protection fault handler checks the opcode that caused the fault for 0x0a77 (sys_sigreturn) and 0x0aad (sys_rt_sigreturn) and injects a system call. This is preferable to the alternative solution with a stub function in the vdso because it works for vdso=off and statically linked binaries as well. Signed-off-by: Martin Schwidefsky

module: s390: keep mod_arch_specific for livepatch modules

2016-04-01T13:00:11Z

Livepatch needs to utilize the symbol information contained in the mod_arch_specific struct in order to be able to call the s390 apply_relocate_add() function to apply relocations. Keep a reference to syminfo if the module is a livepatch module. Remove the redundant vfree() in module_finalize() since module_arch_freeing_init() (which also frees those structures) is called in do_init_module(). If the module isn't a livepatch module, we free the structures in module_arch_freeing_init() as usual. Signed-off-by: Jessica Yu Reviewed-by: Miroslav Benes Acked-by: Josh Poimboeuf Acked-by: Heiko Carstens Signed-off-by: Jiri Kosina

module: use a structure to encapsulate layout.

2015-12-04T21:46:25Z

Makes it easier to handle init vs core cleanly, though the change is fairly invasive across random architectures. It simplifies the rbtree code immediately, however, while keeping the core data together in the same cachline (now iff the rbtree code is enabled). Acked-by: Peter Zijlstra Reviewed-by: Josh Poimboeuf Signed-off-by: Rusty Russell Signed-off-by: Jiri Kosina

s390: remove 31 bit support

2015-03-25T10:49:33Z

Remove the 31 bit support in order to reduce maintenance cost and effectively remove dead code. Since a couple of years there is no distribution left that comes with a 31 bit kernel. The 31 bit kernel also has been broken since more than a year before anybody noticed. In addition I added a removal warning to the kernel shown at ipl for 5 minutes: a960062e5826 ("s390: add 31 bit warning message") which let everybody know about the plan to remove 31 bit code. We didn't get any response. Given that the last 31 bit only machine was introduced in 1999 let's remove the code. Anybody with 31 bit user space code can still use the compat mode. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky

s390/jump label: add missing jump_label_apply_nops() call

2015-02-26T08:24:45Z

When modules are loaded we want to transform the compile time generated nops into runtime generated nops. Otherwise the jump label sanity check will detect invalid code when trying to patch code. Fixes this crash: Jump label code mismatch at __rds_conn_create+0x3c/0x720 Found: c0 04 00 00 00 01 Expected: c0 04 00 00 00 00 Kernel panic - not syncing: Corrupted kernel text CPU: 0 PID: 10 Comm: migration/0 Not tainted 3.19.0-01935-g006610f #14 Call Trace: <0000000000113260> show_trace+0xf8/0x158) <000000000011332a> show_stack+0x6a/0xe8 <000000000069fd64> dump_stack+0x7c/0xd8 <0000000000698d54> panic+0xe4/0x288 <00000000006984c6> jump_label_bug.isra.2+0xbe/0xc001 <000000000011200c> __jump_label_transform+0x94/0xc8 Reported-by: Sebastian Ott Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky