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

treewide: Remove uninitialized_var() usage

2023-08-11T09:33:32Z

commit 3f649ab728cda8038259d8f14492fe400fbab911 upstream. Using uninitialized_var() is dangerous as it papers over real bugs[1] (or can in the future), and suppresses unrelated compiler warnings (e.g. "unused variable"). If the compiler thinks it is uninitialized, either simply initialize the variable or make compiler changes. In preparation for removing[2] the[3] macro[4], remove all remaining needless uses with the following script: git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \ xargs perl -pi -e \ 's/\buninitialized_var$([^$]+)\)/\1/g; s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;' drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid pathological white-space. No outstanding warnings were found building allmodconfig with GCC 9.3.0 for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64, alpha, and m68k. [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/ [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/ [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/ [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/ Reviewed-by: Leon Romanovsky # drivers/infiniband and mlx4/mlx5 Acked-by: Jason Gunthorpe # IB Acked-by: Kalle Valo # wireless drivers Reviewed-by: Chao Yu # erofs Signed-off-by: Kees Cook Signed-off-by: Greg Kroah-Hartman

s390/ptrace: fix PTRACE_GET_LAST_BREAK error handling

2023-04-26T09:18:56Z

[ Upstream commit f9bbf25e7b2b74b52b2f269216a92657774f239c ] Return -EFAULT if put_user() for the PTRACE_GET_LAST_BREAK request fails, instead of silently ignoring it. Reviewed-by: Sven Schnelle Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Sasha Levin

s390/setup: init jump labels before command line parsing

2023-03-11T15:26:55Z

commit 95e61b1b5d6394b53d147c0fcbe2ae70fbe09446 upstream. Command line parameters might set static keys. This is true for s390 at least since commit 6471384af2a6 ("mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options"). To avoid the following WARN: static_key_enable_cpuslocked(): static key 'init_on_alloc+0x0/0x40' used before call to jump_label_init() call jump_label_init() just before parse_early_param(). jump_label_init() is safe to call multiple times (x86 does that), doesn't do any memory allocations and hence should be safe to call that early. Fixes: 6471384af2a6 ("mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options") Cc: # 5.3: d6df52e9996d: s390/maccess: add no DAT mode to kernel_write Cc: # 5.3 Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Heiko Carstens Signed-off-by: Greg Kroah-Hartman

s390/kprobes: fix current_kprobe never cleared after kprobes reenter

2023-03-11T15:26:44Z

commit cd57953936f2213dfaccce10d20f396956222c7d upstream. Recent test_kprobe_missed kprobes kunit test uncovers the following problem. Once kprobe is triggered from another kprobe (kprobe reenter), all future kprobes on this cpu are considered as kprobe reenter, thus pre_handler and post_handler are not being called and kprobes are counted as "missed". Commit b9599798f953 ("[S390] kprobes: activation and deactivation") introduced a simpler scheme for kprobes (de)activation and status tracking by using push_kprobe/pop_kprobe, which supposed to work for both initial kprobe entry as well as kprobe reentry and helps to avoid handling those two cases differently. The problem is that a sequence of calls in case of kprobes reenter: push_kprobe() <- NULL (current_kprobe) push_kprobe() <- kprobe1 (current_kprobe) pop_kprobe() -> kprobe1 (current_kprobe) pop_kprobe() -> kprobe1 (current_kprobe) leaves "kprobe1" as "current_kprobe" on this cpu, instead of setting it to NULL. In fact push_kprobe/pop_kprobe can only store a single state (there is just one prev_kprobe in kprobe_ctlblk). Which is a hack but sufficient, there is no need to have another prev_kprobe just to store NULL. To make a simple and backportable fix simply reset "prev_kprobe" when kprobe is poped from this "stack". No need to worry about "kprobe_status" in this case, because its value is only checked when current_kprobe != NULL. Cc: stable@vger.kernel.org Fixes: b9599798f953 ("[S390] kprobes: activation and deactivation") Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Heiko Carstens Signed-off-by: Greg Kroah-Hartman

s390/kprobes: fix irq mask clobbering on kprobe reenter from post_handler

2023-03-11T15:26:44Z

commit 42e19e6f04984088b6f9f0507c4c89a8152d9730 upstream. Recent test_kprobe_missed kprobes kunit test uncovers the following error (reported when CONFIG_DEBUG_ATOMIC_SLEEP is enabled): BUG: sleeping function called from invalid context at kernel/locking/mutex.c:580 in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 662, name: kunit_try_catch preempt_count: 0, expected: 0 RCU nest depth: 0, expected: 0 no locks held by kunit_try_catch/662. irq event stamp: 280 hardirqs last enabled at (279): [<00000003e60a3d42>] __do_pgm_check+0x17a/0x1c0 hardirqs last disabled at (280): [<00000003e3bd774a>] kprobe_exceptions_notify+0x27a/0x318 softirqs last enabled at (0): [<00000003e3c5c890>] copy_process+0x14a8/0x4c80 softirqs last disabled at (0): [<0000000000000000>] 0x0 CPU: 46 PID: 662 Comm: kunit_try_catch Tainted: G N 6.2.0-173644-g44c18d77f0c0 #2 Hardware name: IBM 3931 A01 704 (LPAR) Call Trace: [<00000003e60a3a00>] dump_stack_lvl+0x120/0x198 [<00000003e3d02e82>] __might_resched+0x60a/0x668 [<00000003e60b9908>] __mutex_lock+0xc0/0x14e0 [<00000003e60bad5a>] mutex_lock_nested+0x32/0x40 [<00000003e3f7b460>] unregister_kprobe+0x30/0xd8 [<00000003e51b2602>] test_kprobe_missed+0xf2/0x268 [<00000003e51b5406>] kunit_try_run_case+0x10e/0x290 [<00000003e51b7dfa>] kunit_generic_run_threadfn_adapter+0x62/0xb8 [<00000003e3ce30f8>] kthread+0x2d0/0x398 [<00000003e3b96afa>] __ret_from_fork+0x8a/0xe8 [<00000003e60ccada>] ret_from_fork+0xa/0x40 The reason for this error report is that kprobes handling code failed to restore irqs. The problem is that when kprobe is triggered from another kprobe post_handler current sequence of enable_singlestep / disable_singlestep is the following: enable_singlestep <- original kprobe (saves kprobe_saved_imask) enable_singlestep <- kprobe triggered from post_handler (clobbers kprobe_saved_imask) disable_singlestep <- kprobe triggered from post_handler (restores kprobe_saved_imask) disable_singlestep <- original kprobe (restores wrong clobbered kprobe_saved_imask) There is just one kprobe_ctlblk per cpu and both calls saves and loads irq mask to kprobe_saved_imask. To fix the problem simply move resume_execution (which calls disable_singlestep) before calling post_handler. This also fixes the problem that post_handler is called with pt_regs which were not yet adjusted after single-stepping. Cc: stable@vger.kernel.org Fixes: 4ba069b802c2 ("[S390] add kprobes support.") Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Heiko Carstens Signed-off-by: Greg Kroah-Hartman

exit: Add and use make_task_dead.

2023-02-06T06:46:33Z

commit 0e25498f8cd43c1b5aa327f373dd094e9a006da7 upstream. There are two big uses of do_exit. The first is it's design use to be the guts of the exit(2) system call. The second use is to terminate a task after something catastrophic has happened like a NULL pointer in kernel code. Add a function make_task_dead that is initialy exactly the same as do_exit to cover the cases where do_exit is called to handle catastrophic failure. In time this can probably be reduced to just a light wrapper around do_task_dead. For now keep it exactly the same so that there will be no behavioral differences introducing this new concept. Replace all of the uses of do_exit that use it for catastraphic task cleanup with make_task_dead to make it clear what the code is doing. As part of this rename rewind_stack_do_exit rewind_stack_and_make_dead. Signed-off-by: "Eric W. Biederman" Signed-off-by: Eric Biggers Signed-off-by: Greg Kroah-Hartman

s390/crashdump: fix TOD programmable field size

2022-12-08T10:16:30Z

[ Upstream commit f44e07a8afdd713ddc1a8832c39372fe5dd86895 ] The size of the TOD programmable field was incorrectly increased from four to eight bytes with commit 1a2c5840acf9 ("s390/dump: cleanup CPU save area handling"). This leads to an elf notes section NT_S390_TODPREG which has a size of eight instead of four bytes in case of kdump, however even worse is that the contents is incorrect: it is supposed to contain only the contents of the TOD programmable field, but in fact contains a mix of the TOD programmable field (32 bit upper bits) and parts of the CPU timer register (lower 32 bits). Fix this by simply changing the size of the todpreg field within the save area structure. This will implicitly also fix the size of the corresponding elf notes sections. This also gets rid of this compile time warning: in function ‘fortify_memcpy_chk’, inlined from ‘save_area_add_regs’ at arch/s390/kernel/crash_dump.c:99:2: ./include/linux/fortify-string.h:413:25: error: call to ‘__read_overflow2_field’ declared with attribute warning: detected read beyond size of field (2nd parameter); maybe use struct_group()? [-Werror=attribute-warning] 413 | __read_overflow2_field(q_size_field, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Fixes: 1a2c5840acf9 ("s390/dump: cleanup CPU save area handling") Reviewed-by: Christian Borntraeger Signed-off-by: Heiko Carstens Signed-off-by: Alexander Gordeev Signed-off-by: Sasha Levin

s390: fix nospec table alignments

2022-09-15T10:23:51Z

commit c9305b6c1f52060377c72aebe3a701389e9f3172 upstream. Add proper alignment for .nospec_call_table and .nospec_return_table in vmlinux. [hca@linux.ibm.com]: The problem with the missing alignment of the nospec tables exist since a long time, however only since commit e6ed91fd0768 ("s390/alternatives: remove padding generation code") and with CONFIG_RELOCATABLE=n the kernel may also crash at boot time. The above named commit reduced the size of struct alt_instr by one byte, so its new size is 11 bytes. Therefore depending on the number of cpu alternatives the size of the __alt_instructions array maybe odd, which again also causes that the addresses of the nospec tables will be odd. If the address of __nospec_call_start is odd and the kernel is compiled With CONFIG_RELOCATABLE=n the compiler may generate code that loads the address of __nospec_call_start with a 'larl' instruction. This will generate incorrect code since the 'larl' instruction only works with even addresses. In result the members of the nospec tables will be accessed with an off-by-one offset, which subsequently may lead to addressing exceptions within __nospec_revert(). Fixes: f19fbd5ed642 ("s390: introduce execute-trampolines for branches") Signed-off-by: Josh Poimboeuf Link: https://lore.kernel.org/r/8719bf1ce4a72ebdeb575200290094e9ce047bcc.1661557333.git.jpoimboe@kernel.org Cc: # 4.16 Reviewed-by: Heiko Carstens Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman

s390/archrandom: simplify back to earlier design and initialize earlier

2022-07-07T15:31:16Z

commit e4f74400308cb8abde5fdc9cad609c2aba32110c upstream. s390x appears to present two RNG interfaces: - a "TRNG" that gathers entropy using some hardware function; and - a "DRBG" that takes in a seed and expands it. Previously, the TRNG was wired up to arch_get_random_{long,int}(), but it was observed that this was being called really frequently, resulting in high overhead. So it was changed to be wired up to arch_get_random_ seed_{long,int}(), which was a reasonable decision. Later on, the DRBG was then wired up to arch_get_random_{long,int}(), with a complicated buffer filling thread, to control overhead and rate. Fortunately, none of the performance issues matter much now. The RNG always attempts to use arch_get_random_seed_{long,int}() first, which means a complicated implementation of arch_get_random_{long,int}() isn't really valuable or useful to have around. And it's only used when reseeding, which means it won't hit the high throughput complications that were faced before. So this commit returns to an earlier design of just calling the TRNG in arch_get_random_seed_{long,int}(), and returning false in arch_get_ random_{long,int}(). Part of what makes the simplification possible is that the RNG now seeds itself using the TRNG at bootup. But this only works if the TRNG is detected early in boot, before random_init() is called. So this commit also causes that check to happen in setup_arch(). Cc: stable@vger.kernel.org Cc: Harald Freudenberger Cc: Ingo Franzki Cc: Juergen Christ Cc: Heiko Carstens Signed-off-by: Jason A. Donenfeld Link: https://lore.kernel.org/r/20220610222023.378448-1-Jason@zx2c4.com Reviewed-by: Harald Freudenberger Acked-by: Heiko Carstens Signed-off-by: Alexander Gordeev Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman

s390/setup: avoid using memblock_enforce_memory_limit

2021-12-08T07:46:53Z

[ Upstream commit 5dbc4cb4667457b0c53bcd7bff11500b3c362975 ] There is a difference in how architectures treat "mem=" option. For some that is an amount of online memory, for s390 and x86 this is the limiting max address. Some memblock api like memblock_enforce_memory_limit() take limit argument and explicitly treat it as the size of online memory, and use __find_max_addr to convert it to an actual max address. Current s390 usage: memblock_enforce_memory_limit(memblock_end_of_DRAM()); yields different results depending on presence of memory holes (offline memory blocks in between online memory). If there are no memory holes limit == max_addr in memblock_enforce_memory_limit() and it does trim online memory and reserved memory regions. With memory holes present it actually does nothing. Since we already use memblock_remove() explicitly to trim online memory regions to potential limit (think mem=, kdump, addressing limits, etc.) drop the usage of memblock_enforce_memory_limit() altogether. Trimming reserved regions should not be required, since we now use memblock_set_current_limit() to limit allocations and any explicit memory reservations above the limit is an actual problem we should not hide. Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Heiko Carstens Signed-off-by: Sasha Levin