kernel.git/arch/s390/include, branch linux-4.19.y

s390/facility: Disable compile time optimization for decompressor code

2024-11-08T15:19:16Z

[ Upstream commit 0147addc4fb72a39448b8873d8acdf3a0f29aa65 ] Disable compile time optimizations of test_facility() for the decompressor. The decompressor should not contain any optimized code depending on the architecture level set the kernel image is compiled for to avoid unexpected operation exceptions. Add a __DECOMPRESSOR check to test_facility() to enforce that facilities are always checked during runtime for the decompressor. Reviewed-by: Sven Schnelle Signed-off-by: Heiko Carstens Signed-off-by: Sasha Levin

asm-generic: Move common compat types to asm-generic/compat.h

2024-07-18T09:39:31Z

commit fb3739759474d150a9927b920a80ea2afb4c2a51 upstream. While converting compat system call handlers to work on 32-bit architectures, I found a number of types used in those handlers that are identical between all architectures. Let's move all the identical ones into asm-generic/compat.h to avoid having to add even more identical definitions of those types. For unknown reasons, mips defines __compat_gid32_t, __compat_uid32_t and compat_caddr_t as signed, while all others have them unsigned. This seems to be a mistake, but I'm leaving it alone here. The other types all differ by size or alignment on at least on architecture. compat_aio_context_t is currently defined in linux/compat.h but also needed for compat_sys_io_getevents(), so let's move it into the same place. While we still have not decided whether the 32-bit time handling will always use the compat syscalls, or in which form, I think this is a useful cleanup that we can merge regardless. Reviewed-by: Christoph Hellwig Signed-off-by: Arnd Bergmann Cc: Frank Scheiner Signed-off-by: Greg Kroah-Hartman

s390/vx: fix save/restore of fpu kernel context

2024-01-08T10:27:33Z

[ Upstream commit e6b2dab41888332bf83f592131e7ea07756770a4 ] The KERNEL_FPR mask only contains a flag for the first eight vector registers. However floating point registers overlay parts of the first sixteen vector registers. This could lead to vector register corruption if a kernel fpu context uses any of the vector registers 8 to 15 and is interrupted or calls a KERNEL_FPR context. If that context uses also vector registers 8 to 15, their contents will be corrupted on return. Luckily this is currently not a real bug, since the kernel has only one KERNEL_FPR user with s390_adjust_jiffies() and it is only using floating point registers 0 to 2. Fix this by using the correct bits for KERNEL_FPR. Fixes: 7f79695cc1b6 ("s390/fpu: improve kernel_fpu_[begin|end]") Signed-off-by: Heiko Carstens Reviewed-by: Hendrik Brueckner Signed-off-by: Alexander Gordeev Signed-off-by: Sasha Levin

s390/percpu: add READ_ONCE() to arch_this_cpu_to_op_simple()

2023-01-18T10:30:52Z

commit e3f360db08d55a14112bd27454e616a24296a8b0 upstream. Make sure that *ptr__ within arch_this_cpu_to_op_simple() is only dereferenced once by using READ_ONCE(). Otherwise the compiler could generate incorrect code. Cc: Reviewed-by: Alexander Gordeev Signed-off-by: Heiko Carstens Signed-off-by: Greg Kroah-Hartman

s390/futex: add missing EX_TABLE entry to __futex_atomic_op()

2022-11-03T14:52:29Z

commit a262d3ad6a433e4080cecd0a8841104a5906355e upstream. For some exception types the instruction address points behind the instruction that caused the exception. Take that into account and add the missing exception table entry. Cc: Reviewed-by: Vasily Gorbik Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman

s390/hugetlb: fix prepare_hugepage_range() check for 2 GB hugepages

2022-09-15T10:17:04Z

commit 7c8d42fdf1a84b1a0dd60d6528309c8ec127e87c upstream. The alignment check in prepare_hugepage_range() is wrong for 2 GB hugepages, it only checks for 1 MB hugepage alignment. This can result in kernel crash in __unmap_hugepage_range() at the BUG_ON(start & ~huge_page_mask(h)) alignment check, for mappings created with MAP_FIXED at unaligned address. Fix this by correctly handling multiple hugepage sizes, similar to the generic version of prepare_hugepage_range(). Fixes: d08de8e2d867 ("s390/mm: add support for 2GB hugepages") Cc: # 4.8+ Acked-by: Alexander Gordeev Signed-off-by: Gerald Schaefer Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman

s390/archrandom: prevent CPACF trng invocations in interrupt context

2022-08-11T10:48:38Z

commit 918e75f77af7d2e049bb70469ec0a2c12782d96a upstream. This patch slightly reworks the s390 arch_get_random_seed_{int,long} implementation: Make sure the CPACF trng instruction is never called in any interrupt context. This is done by adding an additional condition in_task(). Justification: There are some constrains to satisfy for the invocation of the arch_get_random_seed_{int,long}() functions: - They should provide good random data during kernel initialization. - They should not be called in interrupt context as the TRNG instruction is relatively heavy weight and may for example make some network loads cause to timeout and buck. However, it was not clear what kind of interrupt context is exactly encountered during kernel init or network traffic eventually calling arch_get_random_seed_long(). After some days of investigations it is clear that the s390 start_kernel function is not running in any interrupt context and so the trng is called: Jul 11 18:33:39 t35lp54 kernel: [<00000001064e90ca>] arch_get_random_seed_long.part.0+0x32/0x70 Jul 11 18:33:39 t35lp54 kernel: [<000000010715f246>] random_init+0xf6/0x238 Jul 11 18:33:39 t35lp54 kernel: [<000000010712545c>] start_kernel+0x4a4/0x628 Jul 11 18:33:39 t35lp54 kernel: [<000000010590402a>] startup_continue+0x2a/0x40 The condition in_task() is true and the CPACF trng provides random data during kernel startup. The network traffic however, is more difficult. A typical call stack looks like this: Jul 06 17:37:07 t35lp54 kernel: [<000000008b5600fc>] extract_entropy.constprop.0+0x23c/0x240 Jul 06 17:37:07 t35lp54 kernel: [<000000008b560136>] crng_reseed+0x36/0xd8 Jul 06 17:37:07 t35lp54 kernel: [<000000008b5604b8>] crng_make_state+0x78/0x340 Jul 06 17:37:07 t35lp54 kernel: [<000000008b5607e0>] _get_random_bytes+0x60/0xf8 Jul 06 17:37:07 t35lp54 kernel: [<000000008b56108a>] get_random_u32+0xda/0x248 Jul 06 17:37:07 t35lp54 kernel: [<000000008aefe7a8>] kfence_guarded_alloc+0x48/0x4b8 Jul 06 17:37:07 t35lp54 kernel: [<000000008aeff35e>] __kfence_alloc+0x18e/0x1b8 Jul 06 17:37:07 t35lp54 kernel: [<000000008aef7f10>] __kmalloc_node_track_caller+0x368/0x4d8 Jul 06 17:37:07 t35lp54 kernel: [<000000008b611eac>] kmalloc_reserve+0x44/0xa0 Jul 06 17:37:07 t35lp54 kernel: [<000000008b611f98>] __alloc_skb+0x90/0x178 Jul 06 17:37:07 t35lp54 kernel: [<000000008b6120dc>] __napi_alloc_skb+0x5c/0x118 Jul 06 17:37:07 t35lp54 kernel: [<000000008b8f06b4>] qeth_extract_skb+0x13c/0x680 Jul 06 17:37:07 t35lp54 kernel: [<000000008b8f6526>] qeth_poll+0x256/0x3f8 Jul 06 17:37:07 t35lp54 kernel: [<000000008b63d76e>] __napi_poll.constprop.0+0x46/0x2f8 Jul 06 17:37:07 t35lp54 kernel: [<000000008b63dbec>] net_rx_action+0x1cc/0x408 Jul 06 17:37:07 t35lp54 kernel: [<000000008b937302>] __do_softirq+0x132/0x6b0 Jul 06 17:37:07 t35lp54 kernel: [<000000008abf46ce>] __irq_exit_rcu+0x13e/0x170 Jul 06 17:37:07 t35lp54 kernel: [<000000008abf531a>] irq_exit_rcu+0x22/0x50 Jul 06 17:37:07 t35lp54 kernel: [<000000008b922506>] do_io_irq+0xe6/0x198 Jul 06 17:37:07 t35lp54 kernel: [<000000008b935826>] io_int_handler+0xd6/0x110 Jul 06 17:37:07 t35lp54 kernel: [<000000008b9358a6>] psw_idle_exit+0x0/0xa Jul 06 17:37:07 t35lp54 kernel: ([<000000008ab9c59a>] arch_cpu_idle+0x52/0xe0) Jul 06 17:37:07 t35lp54 kernel: [<000000008b933cfe>] default_idle_call+0x6e/0xd0 Jul 06 17:37:07 t35lp54 kernel: [<000000008ac59f4e>] do_idle+0xf6/0x1b0 Jul 06 17:37:07 t35lp54 kernel: [<000000008ac5a28e>] cpu_startup_entry+0x36/0x40 Jul 06 17:37:07 t35lp54 kernel: [<000000008abb0d90>] smp_start_secondary+0x148/0x158 Jul 06 17:37:07 t35lp54 kernel: [<000000008b935b9e>] restart_int_handler+0x6e/0x90 which confirms that the call is in softirq context. So in_task() covers exactly the cases where we want to have CPACF trng called: not in nmi, not in hard irq, not in soft irq but in normal task context and during kernel init. Signed-off-by: Harald Freudenberger Acked-by: Jason A. Donenfeld Reviewed-by: Juergen Christ Link: https://lore.kernel.org/r/20220713131721.257907-1-freude@linux.ibm.com Fixes: e4f74400308c ("s390/archrandom: simplify back to earlier design and initialize earlier") [agordeev@linux.ibm.com changed desc, added Fixes and Link, removed -stable] Signed-off-by: Alexander Gordeev Signed-off-by: Greg Kroah-Hartman

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

2022-07-07T15:35:09Z

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

kexec_file: drop weak attribute from arch_kexec_apply_relocations[_add]

2022-07-02T14:27:39Z

commit 3e35142ef99fe6b4fe5d834ad43ee13cca10a2dc upstream. Since commit d1bcae833b32f1 ("ELF: Don't generate unused section symbols") [1], binutils (v2.36+) started dropping section symbols that it thought were unused. This isn't an issue in general, but with kexec_file.c, gcc is placing kexec_arch_apply_relocations[_add] into a separate .text.unlikely section and the section symbol ".text.unlikely" is being dropped. Due to this, recordmcount is unable to find a non-weak symbol in .text.unlikely to generate a relocation record against. Address this by dropping the weak attribute from these functions. Instead, follow the existing pattern of having architectures #define the name of the function they want to override in their headers. [1] https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=d1bcae833b32f1 [akpm@linux-foundation.org: arch/s390/include/asm/kexec.h needs linux/module.h] Link: https://lkml.kernel.org/r/20220519091237.676736-1-naveen.n.rao@linux.vnet.ibm.com Signed-off-by: Michael Ellerman Signed-off-by: Naveen N. Rao Cc: "Eric W. Biederman" Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

s390: define get_cycles macro for arch-override

2022-06-25T09:49:09Z

commit 2e3df523256cb9836de8441e9c791a796759bb3c upstream. S390x defines a get_cycles() function, but it does not do the usual `#define get_cycles get_cycles` dance, making it impossible for generic code to see if an arch-specific function was defined. While the get_cycles() ifdef is not currently used, the following timekeeping patch in this series will depend on the macro existing (or not existing) when defining random_get_entropy(). Cc: Thomas Gleixner Cc: Arnd Bergmann Cc: Vasily Gorbik Cc: Alexander Gordeev Cc: Christian Borntraeger Cc: Sven Schnelle Acked-by: Heiko Carstens Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman