kernel/git/stable/linux.git/arch/parisc, branch linux-5.8.y

parisc: Implement __smp_store_release and __smp_load_acquire barriers

2020-08-19T06:27:07+00:00

commit e96ebd589debd9a6a793608c4ec7019c38785dea upstream. This patch implements the __smp_store_release and __smp_load_acquire barriers using ordered stores and loads. This avoids the sync instruction present in the generic implementation. Cc: # 4.14+ Signed-off-by: Dave Anglin Signed-off-by: Helge Deller Signed-off-by: Greg Kroah-Hartman

parisc: Do not use an ordered store in pa_tlb_lock()

2020-08-19T06:27:07+00:00

commit e72b23dec1da5e62a0090c5da1d926778284e230 upstream. No need to use an ordered store in pa_tlb_lock() and update the comment regarng usage of the sid register to unlocak a spinlock in tlb_unlock0(). Signed-off-by: John David Anglin Signed-off-by: Helge Deller Cc: # v5.0+ Signed-off-by: Greg Kroah-Hartman

Revert "parisc: Revert "Release spinlocks using ordered store""

2020-08-19T06:27:07+00:00

commit 157e9afcc4fa25068b0e8743bc254a9b56010e13 upstream. This reverts commit 86d4d068df573a8c2105554624796c086d6bec3d. Signed-off-by: Helge Deller Cc: # v5.0+ Signed-off-by: Greg Kroah-Hartman

Revert "parisc: Use ldcw instruction for SMP spinlock release barrier"

2020-08-19T06:27:07+00:00

commit 6e9f06ee6c9566f3606d93182ac8f803a148504b upstream. This reverts commit 9e5c602186a692a7e848c0da17aed40f49d30519. No need to use the ldcw instruction as SMP spinlock release barrier. Revert it to gain back speed again. Signed-off-by: Helge Deller Cc: # v5.2+ Signed-off-by: Greg Kroah-Hartman

Revert "parisc: Drop LDCW barrier in CAS code when running UP"

2020-08-19T06:27:07+00:00

commit 462fb756c7de1ffe5bc6099149136031c2d9c02a upstream. This reverts commit e6eb5fe9123f05dcbf339ae5c0b6d32fcc0685d5. We need to optimize it differently. A follow up patch will correct it. Signed-off-by: Helge Deller Cc: # v5.2+ Signed-off-by: Greg Kroah-Hartman

Revert "parisc: Improve interrupt handling in arch_spin_lock_flags()"

2020-08-19T06:27:06+00:00

commit 3d05b8aebc5f10ee3ab129b61100196855dd7249 upstream. This reverts commit 2772f0efd5bbd5413db3d22e363b779ca0fa5310. It turns out that we want to implement the spinlock code differently. Signed-off-by: Helge Deller Cc: # v5.7+ Signed-off-by: Greg Kroah-Hartman

parisc: Add atomic64_set_release() define to avoid CPU soft lockups

2020-07-21T15:16:37+00:00

Stalls are quite frequent with recent kernels. I enabled CONFIG_SOFTLOCKUP_DETECTOR and I caught the following stall: watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [cc1:22803] CPU: 0 PID: 22803 Comm: cc1 Not tainted 5.6.17+ #3 Hardware name: 9000/800/rp3440 IAOQ[0]: d_alloc_parallel+0x384/0x688 IAOQ[1]: d_alloc_parallel+0x388/0x688 RP(r2): d_alloc_parallel+0x134/0x688 Backtrace: [<000000004036974c>] __lookup_slow+0xa4/0x200 [<0000000040369fc8>] walk_component+0x288/0x458 [<000000004036a9a0>] path_lookupat+0x88/0x198 [<000000004036e748>] filename_lookup+0xa0/0x168 [<000000004036e95c>] user_path_at_empty+0x64/0x80 [<000000004035d93c>] vfs_statx+0x104/0x158 [<000000004035dfcc>] __do_sys_lstat64+0x44/0x80 [<000000004035e5a0>] sys_lstat64+0x20/0x38 [<0000000040180054>] syscall_exit+0x0/0x14 The code was stuck in this loop in d_alloc_parallel: 4037d414: 0e 00 10 dc ldd 0(r16),ret0 4037d418: c7 fc 5f ed bb,< ret0,1f,4037d414 4037d41c: 08 00 02 40 nop This is the inner loop of bit_spin_lock which is called by hlist_bl_unlock in d_alloc_parallel: static inline void bit_spin_lock(int bitnum, unsigned long *addr) { /* * Assuming the lock is uncontended, this never enters * the body of the outer loop. If it is contended, then * within the inner loop a non-atomic test is used to * busywait with less bus contention for a good time to * attempt to acquire the lock bit. */ preempt_disable(); #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) while (unlikely(test_and_set_bit_lock(bitnum, addr))) { preempt_enable(); do { cpu_relax(); } while (test_bit(bitnum, addr)); preempt_disable(); } #endif __acquire(bitlock); } After consideration, I realized that we must be losing bit unlocks. Then, I noticed that we missed defining atomic64_set_release(). Adding this define fixes the stalls in bit operations. Signed-off-by: Dave Anglin Cc: stable@vger.kernel.org Signed-off-by: Helge Deller

parisc: add support for cmpxchg on u8 pointers

2020-07-21T06:11:12+00:00

The kernel test bot reported[1] that using set_mask_bits on a u8 causes the following issue on parisc: hppa-linux-ld: drivers/phy/ti/phy-tusb1210.o: in function `tusb1210_probe': >> (.text+0x2f4): undefined reference to `__cmpxchg_called_with_bad_pointer' >> hppa-linux-ld: (.text+0x324): undefined reference to `__cmpxchg_called_with_bad_pointer' hppa-linux-ld: (.text+0x354): undefined reference to `__cmpxchg_called_with_bad_pointer' Add support for cmpxchg on u8 pointers. [1] https://lore.kernel.org/patchwork/patch/1272617/#1468946 Reported-by: kernel test robot Signed-off-by: Liam Beguin Tested-by: Dave Anglin Signed-off-by: Helge Deller

maccess: make get_kernel_nofault() check for minimal type compatibility

2020-06-18T19:10:37+00:00

Now that we've renamed probe_kernel_address() to get_kernel_nofault() and made it look and behave more in line with get_user(), some of the subtle type behavior differences end up being more obvious and possibly dangerous. When you do get_user(val, user_ptr); the type of the access comes from the "user_ptr" part, and the above basically acts as val = *user_ptr; by design (except, of course, for the fact that the actual dereference is done with a user access). Note how in the above case, the type of the end result comes from the pointer argument, and then the value is cast to the type of 'val' as part of the assignment. So the type of the pointer is ultimately the more important type both for the access itself. But 'get_kernel_nofault()' may now _look_ similar, but it behaves very differently. When you do get_kernel_nofault(val, kernel_ptr); it behaves like val = *(typeof(val) *)kernel_ptr; except, of course, for the fact that the actual dereference is done with exception handling so that a faulting access is suppressed and returned as the error code. But note how different the casting behavior of the two superficially similar accesses are: one does the actual access in the size of the type the pointer points to, while the other does the access in the size of the target, and ignores the pointer type entirely. Actually changing get_kernel_nofault() to act like get_user() is almost certainly the right thing to do eventually, but in the meantime this patch adds logit to at least verify that the pointer type is compatible with the type of the result. In many cases, this involves just casting the pointer to 'void *' to make it obvious that the type of the pointer is not the important part. It's not how 'get_user()' acts, but at least the behavioral difference is now obvious and explicit. Cc: Christoph Hellwig Signed-off-by: Linus Torvalds

maccess: rename probe_kernel_address to get_kernel_nofault

2020-06-18T18:14:40+00:00

Better describe what this helper does, and match the naming of copy_from_kernel_nofault. Also switch the argument order around, so that it acts and looks like get_user(). Signed-off-by: Christoph Hellwig Signed-off-by: Linus Torvalds