kernel/git/stable/linux.git/arch/s390/include, branch linux-5.5.y

s390: prevent leaking kernel address in BEAR

2020-04-13T11:16:33+00:00

commit 0b38b5e1d0e2f361e418e05c179db05bb688bbd6 upstream. When userspace executes a syscall or gets interrupted, BEAR contains a kernel address when returning to userspace. This make it pretty easy to figure out where the kernel is mapped even with KASLR enabled. To fix this, add lpswe to lowcore and always execute it there, so userspace sees only the lowcore address of lpswe. For this we have to extend both critical_cleanup and the SWITCH_ASYNC macro to also check for lpswe addresses in lowcore. Fixes: b2d24b97b2a9 ("s390/kernel: add support for kernel address space layout randomization (KASLR)") Cc: # v5.2+ Reviewed-by: Gerald Schaefer Signed-off-by: Sven Schnelle Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman

s390/mm: fix panic in gup_fast on large pud

2020-03-12T06:18:35+00:00

commit 582b4e55403e053d8a48ff687a05174da9cc3fb0 upstream. On s390 there currently is no implementation of pud_write(). That was ok as long as we had our own implementation of get_user_pages_fast() which checked for pud protection by testing the bit directly w/o using pud_write(). The other callers of pud_write() are not reachable on s390. After commit 1a42010cdc26 ("s390/mm: convert to the generic get_user_pages_fast code") we use the generic get_user_pages_fast(), which does call pud_write() in pud_access_permitted() for FOLL_WRITE access on a large pud. Without an s390 specific pud_write(), the generic version is called, which contains a BUG() statement to remind us that we don't have a proper implementation. This results in a kernel panic. Fix this by providing an implementation of pud_write(). Cc: # 5.2+ Fixes: 1a42010cdc26 ("s390/mm: convert to the generic get_user_pages_fast code") Signed-off-by: Gerald Schaefer Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman

s390/qdio: fill SL with absolute addresses

2020-03-12T06:18:27+00:00

[ Upstream commit e9091ffd6a0aaced111b5d6ead5eaab5cd7101bc ] As the comment says, sl->sbal holds an absolute address. qeth currently solves this through wild casting, while zfcp doesn't care. Handle this properly in the code that actually builds the SL. Signed-off-by: Julian Wiedmann Reviewed-by: Alexandra Winter Reviewed-by: Steffen Maier [for qdio] Reviewed-by: Benjamin Block Signed-off-by: Vasily Gorbik Signed-off-by: Sasha Levin

s390/mm: Explicitly compare PAGE_DEFAULT_KEY against zero in storage_key_init_range

2020-02-28T16:23:45+00:00

commit 380324734956c64cd060e1db4304f3117ac15809 upstream. Clang warns: In file included from ../arch/s390/purgatory/purgatory.c:10: In file included from ../include/linux/kexec.h:18: In file included from ../include/linux/crash_core.h:6: In file included from ../include/linux/elfcore.h:5: In file included from ../include/linux/user.h:1: In file included from ../arch/s390/include/asm/user.h:11: ../arch/s390/include/asm/page.h:45:6: warning: converting the result of '<<' to a boolean always evaluates to false [-Wtautological-constant-compare] if (PAGE_DEFAULT_KEY) ^ ../arch/s390/include/asm/page.h:23:44: note: expanded from macro 'PAGE_DEFAULT_KEY' #define PAGE_DEFAULT_KEY (PAGE_DEFAULT_ACC << 4) ^ 1 warning generated. Explicitly compare this against zero to silence the warning as it is intended to be used in a boolean context. Fixes: de3fa841e429 ("s390/mm: fix compile for PAGE_DEFAULT_KEY != 0") Link: https://github.com/ClangBuiltLinux/linux/issues/860 Link: https://lkml.kernel.org/r/20200214064207.10381-1-natechancellor@gmail.com Acked-by: Christian Borntraeger Signed-off-by: Nathan Chancellor Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman

s390/pci: Recover handle in clp_set_pci_fn()

2020-02-24T07:38:51+00:00

[ Upstream commit 17cdec960cf776b20b1fb08c622221babe591d51 ] When we try to recover a PCI function using echo 1 > /sys/bus/pci/devices//recover or manually with echo 1 > /sys/bus/pci/devices//remove echo 0 > /sys/bus/pci/slots//power echo 1 > /sys/bus/pci/slots//power clp_disable_fn() / clp_enable_fn() call clp_set_pci_fn() to first disable and then reenable the function. When the function is already in the requested state we may be left with an invalid function handle. To get a new valid handle we do a clp_list_pci() call. For this we need both the function ID and function handle in clp_set_pci_fn() so pass the zdev and get both. To simplify things also pull setting the refreshed function handle into clp_set_pci_fn() Signed-off-by: Niklas Schnelle Reviewed-by: Peter Oberparleiter Signed-off-by: Vasily Gorbik Signed-off-by: Sasha Levin

s390: fix __EMIT_BUG() macro

2020-02-24T07:38:39+00:00

[ Upstream commit 17248ea0367465f4aaef728f6af661ed38e38cf1 ] Setting a kprobe on getname_flags() failed: $ echo 'p:tmr1 getname_flags +0(%r2):ustring' > kprobe_events -bash: echo: write error: Invalid argument Debugging the kprobes code showed that the address of getname_flags() is contained in the __bug_table. Kprobes doesn't allow to set probes at BUG() locations. $ objdump -j __bug_table -x build/fs/namei.o [..] 0000000000000108 R_390_PC32 .text+0x00000000000075a8 000000000000010c R_390_PC32 .L223+0x0000000000000004 I was expecting getname_flags() to start with a BUG(), but: 7598: e3 20 10 00 00 04 lg %r2,0(%r1) 759e: c0 f4 00 00 00 00 jg 759e 75a0: R_390_PLT32DBL kmem_cache_free+0x2 75a4: a7 f4 00 01 j 75a6 00000000000075a8 : 75a8: c0 04 00 00 00 00 brcl 0,75a8 75ae: eb 6f f0 48 00 24 stmg %r6,%r15,72(%r15) 75b4: b9 04 00 ef lgr %r14,%r15 75b8: e3 f0 ff a8 ff 71 lay %r15,-88(%r15) So the BUG() is actually the last opcode of the previous function. Fix this by switching to using the MONITOR CALL (MC) instruction, and set the entry in __bug_table to the beginning of that MC. Reviewed-by: Heiko Carstens Signed-off-by: Sven Schnelle Signed-off-by: Vasily Gorbik Signed-off-by: Sasha Levin

s390/time: Fix clk type in get_tod_clock

2020-02-19T18:54:09+00:00

commit 0f8a206df7c920150d2aa45574fba0ab7ff6be4f upstream. Clang warns: In file included from ../arch/s390/boot/startup.c:3: In file included from ../include/linux/elf.h:5: In file included from ../arch/s390/include/asm/elf.h:132: In file included from ../include/linux/compat.h:10: In file included from ../include/linux/time.h:74: In file included from ../include/linux/time32.h:13: In file included from ../include/linux/timex.h:65: ../arch/s390/include/asm/timex.h:160:20: warning: passing 'unsigned char [16]' to parameter of type 'char *' converts between pointers to integer types with different sign [-Wpointer-sign] get_tod_clock_ext(clk); ^~~ ../arch/s390/include/asm/timex.h:149:44: note: passing argument to parameter 'clk' here static inline void get_tod_clock_ext(char *clk) ^ Change clk's type to just be char so that it matches what happens in get_tod_clock_ext. Fixes: 57b28f66316d ("[S390] s390_hypfs: Add new attributes") Link: https://github.com/ClangBuiltLinux/linux/issues/861 Link: http://lkml.kernel.org/r/20200208140858.47970-1-natechancellor@gmail.com Reviewed-by: Nick Desaulniers Signed-off-by: Nathan Chancellor Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman

s390/mm: fix dynamic pagetable upgrade for hugetlbfs

2020-02-11T12:36:48+00:00

commit 5f490a520bcb393389a4d44bec90afcb332eb112 upstream. Commit ee71d16d22bb ("s390/mm: make TASK_SIZE independent from the number of page table levels") changed the logic of TASK_SIZE and also removed the arch_mmap_check() implementation for s390. This combination has a subtle effect on how get_unmapped_area() for hugetlbfs pages works. It is now possible that a user process establishes a hugetlbfs mapping at an address above 4 TB, without triggering a dynamic pagetable upgrade from 3 to 4 levels. This is because hugetlbfs mappings will not use mm->get_unmapped_area, but rather file->f_op->get_unmapped_area, which currently is the generic implementation of hugetlb_get_unmapped_area() that does not know about s390 dynamic pagetable upgrades, but with the new definition of TASK_SIZE, it will now allow mappings above 4 TB. Subsequent access to such a mapped address above 4 TB will result in a page fault loop, because the CPU cannot translate such a large address with 3 pagetable levels. The fault handler will try to map in a hugepage at the address, but due to the folded pagetable logic it will end up with creating entries in the 3 level pagetable, possibly overwriting existing mappings, and then it all repeats when the access is retried. Apart from the page fault loop, this can have various nasty effects, e.g. kernel panic from one of the BUG_ON() checks in memory management code, or even data loss if an existing mapping gets overwritten. Fix this by implementing HAVE_ARCH_HUGETLB_UNMAPPED_AREA support for s390, providing an s390 version for hugetlb_get_unmapped_area() with pagetable upgrade support similar to arch_get_unmapped_area(), which will then be used instead of the generic version. Fixes: ee71d16d22bb ("s390/mm: make TASK_SIZE independent from the number of page table levels") Cc: # 4.12+ Signed-off-by: Gerald Schaefer Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman

s390/ftrace: fix endless recursion in function_graph tracer

2019-12-18T22:29:26+00:00

The following sequence triggers a kernel stack overflow on s390x: mount -t tracefs tracefs /sys/kernel/tracing cd /sys/kernel/tracing echo function_graph > current_tracer [crash] This is because preempt_count_{add,sub} are in the list of traced functions, which can be demonstrated by: echo preempt_count_add >set_ftrace_filter echo function_graph > current_tracer [crash] The stack overflow happens because get_tod_clock_monotonic() gets called by ftrace but itself calls preempt_{disable,enable}(), which leads to a endless recursion. Fix this by using preempt_{disable,enable}_notrace(). Fixes: 011620688a71 ("s390/time: ensure get_clock_monotonic() returns monotonic values") Signed-off-by: Sven Schnelle Reviewed-by: Vasily Gorbik Signed-off-by: Vasily Gorbik

s390: remove last diag 0x44 caller

2019-12-11T18:53:24+00:00

diag 0x44 is a voluntary undirected yield of a virtual CPU. This has caused a lot of performance issues in the past. There is only one caller left, and that one is only executed if diag 0x9c (directed yield) is not present. Given that all hypervisors implement diag 0x9c anyway, remove the last diag 0x44 to avoid that more callers will be added. Worst case that could happen now, if diag 0x9c is not present, is that a virtual CPU would loop a bit instead of giving its time slice up. diag 0x44 statistics in debugfs are kept and will always be zero, so that user space can tell that there are no calls. Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik