From 034dd340b08be1f2f0477ad16131d609f9dbd53c Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 30 Aug 2026 09:22:00 -0700 Subject: Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull tracing fixes from Steven Rostedt: - Fix error output of boot instance creation failure Currently if a boot instance creation fails, instead of printing out the name of the instance that failed, it prints "(null)". That is because it prints "cur_str" that had already been processed by strsep(). Print the saved name instead. While at it, print the error code of the failure. - Fix use-after-free for same named historgrams Histograms can be named so that they can be used in multiple events. But if the named histogram has a variable attached, the second event that uses the named histogram which duplicates it and needs to free the original after duplication leaves the old variable in place and still visible. If another histogram uses than variable, it will use the stale one which will try to reference the freed duplicate histogram and crash the kernel. Free the duplicate variables along with the duplicated histogram data. - Check return value of kthread_run() in event self test The events self tests uses a kthread for testing but does not check if it succeeded in creating a kthread. If the kthread creation were to fail, the code will still try to call kthread_stop() on the error returned. - Fix race between reading trace_pipe and updating subbuffer size If a user is reading the trace_pipe file at the same time they update the ring buffer sub-buffer size, can cause the trace_pipe read to read stale data. Add trace_access_lock() around updating the ring buffer sub-buffer size. - Fix eventfs_inode on failure path in creation of the events directory In the creation of the "events" directory, if after allocating the eventfs_inode a failure is detected, it calls cleanup_ei() which calls free_ei(). The free_ei() will test if eventfs_inode being freed has no children. It is a bug if it does. But on the failure case of the creation of the "events" directory, the children lists have not yet been initialized and the free will trigger a warning because list_empty() on an uninitialized list returns false. Move the initialization into init_ei() where it makes more sense and makes sure that a created eventfs_inode has its lists initialized upon creation. - Check return value of kthread_run() in ftrace direct sample code The sample code that shows how to use the ftrace direct calls does not test the return of kthread_run() to see if it succeeds. Return a failure if the kthread_run() doesn't succeed. - Clear user events state on fork in case of alloc failure On fork, the child gets a pointer to the parent's user events state. It makes a copy of it then updates the child's pointer to it. But if the allocation fails, the duplication function leaves the child with a pointer to its parent's descriptor. When the child cleans up its data, it will free the parent's descriptor while the parent is still using it. In the duplication function, set the child's user_event_mm to NULL before testing if the allocation succeeded, and when it exits it will not free the parent's descriptor. - Fix retry exhaustion in simple ring buffer reader swap simple_ring_buffer_swap_reader_page() starts with retry set to 8 and post-decrements it only after a failed link replacement. On the final attempt, a successful replacement leaves retry at zero, while a failed replacement leaves it at -1. But the check for success expects the retry value to be non-zero and exits with an error on zero. This is the opposite result. Fix it. - Fail nicely when the remote swap_reader_page() returns an error Currently, if the swap_reader_page() of a remote buffer fails, it triggers a WARN_ON_ONCE() and continues normally. Instead, have it exit with an error and a pr_warn() print instead of a full WARNING. * tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: ring-buffer: Stop remote reader update when page swap fails tracing: Fix retry exhaustion in simple ring buffer reader swap tracing/user_events: Clear copied tracing state before fork duplication samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify eventfs: Initialize ei->children and ei->list in init_ei() tracing: Fix use-after-free in trace_pipe read on sub-buffer order change tracing: Fix crash passing ERR_PTR to kthread_stop() tracing: Fix use-after-free with same-name named triggers tracing: Fix logged instance name on creation failure --- arch/mips/mm/context.c | 290 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 290 insertions(+) create mode 100644 arch/mips/mm/context.c (limited to 'arch/mips/mm/context.c') diff --git a/arch/mips/mm/context.c b/arch/mips/mm/context.c new file mode 100644 index 000000000..966f40066 --- /dev/null +++ b/arch/mips/mm/context.c @@ -0,0 +1,290 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include + +static DEFINE_RAW_SPINLOCK(cpu_mmid_lock); + +static atomic64_t mmid_version; +static unsigned int num_mmids; +static unsigned long *mmid_map; + +static DEFINE_PER_CPU(u64, reserved_mmids); +static cpumask_t tlb_flush_pending; + +static bool asid_versions_eq(int cpu, u64 a, u64 b) +{ + return ((a ^ b) & asid_version_mask(cpu)) == 0; +} + +void get_new_mmu_context(struct mm_struct *mm) +{ + unsigned int cpu; + u64 asid; + + /* + * This function is specific to ASIDs, and should not be called when + * MMIDs are in use. + */ + if (WARN_ON(IS_ENABLED(CONFIG_DEBUG_VM) && cpu_has_mmid)) + return; + + cpu = smp_processor_id(); + asid = asid_cache(cpu); + + if (!((asid += cpu_asid_inc()) & cpu_asid_mask(&cpu_data[cpu]))) { + if (cpu_has_vtag_icache) + flush_icache_all(); + local_flush_tlb_all(); /* start new asid cycle */ + } + + set_cpu_context(cpu, mm, asid); + asid_cache(cpu) = asid; +} +EXPORT_SYMBOL_GPL(get_new_mmu_context); + +void check_mmu_context(struct mm_struct *mm) +{ + unsigned int cpu = smp_processor_id(); + + /* + * This function is specific to ASIDs, and should not be called when + * MMIDs are in use. + */ + if (WARN_ON(IS_ENABLED(CONFIG_DEBUG_VM) && cpu_has_mmid)) + return; + + /* Check if our ASID is of an older version and thus invalid */ + if (!asid_versions_eq(cpu, cpu_context(cpu, mm), asid_cache(cpu))) + get_new_mmu_context(mm); +} +EXPORT_SYMBOL_GPL(check_mmu_context); + +static void flush_context(void) +{ + u64 mmid; + int cpu; + + /* Update the list of reserved MMIDs and the MMID bitmap */ + bitmap_zero(mmid_map, num_mmids); + + /* Reserve an MMID for kmap/wired entries */ + __set_bit(MMID_KERNEL_WIRED, mmid_map); + + for_each_possible_cpu(cpu) { + mmid = xchg_relaxed(&cpu_data[cpu].asid_cache, 0); + + /* + * If this CPU has already been through a + * rollover, but hasn't run another task in + * the meantime, we must preserve its reserved + * MMID, as this is the only trace we have of + * the process it is still running. + */ + if (mmid == 0) + mmid = per_cpu(reserved_mmids, cpu); + + __set_bit(mmid & cpu_asid_mask(&cpu_data[cpu]), mmid_map); + per_cpu(reserved_mmids, cpu) = mmid; + } + + /* + * Queue a TLB invalidation for each CPU to perform on next + * context-switch + */ + cpumask_setall(&tlb_flush_pending); +} + +static bool check_update_reserved_mmid(u64 mmid, u64 newmmid) +{ + bool hit; + int cpu; + + /* + * Iterate over the set of reserved MMIDs looking for a match. + * If we find one, then we can update our mm to use newmmid + * (i.e. the same MMID in the current generation) but we can't + * exit the loop early, since we need to ensure that all copies + * of the old MMID are updated to reflect the mm. Failure to do + * so could result in us missing the reserved MMID in a future + * generation. + */ + hit = false; + for_each_possible_cpu(cpu) { + if (per_cpu(reserved_mmids, cpu) == mmid) { + hit = true; + per_cpu(reserved_mmids, cpu) = newmmid; + } + } + + return hit; +} + +static u64 get_new_mmid(struct mm_struct *mm) +{ + static u32 cur_idx = MMID_KERNEL_WIRED + 1; + u64 mmid, version, mmid_mask; + + mmid = cpu_context(0, mm); + version = atomic64_read(&mmid_version); + mmid_mask = cpu_asid_mask(&boot_cpu_data); + + if (!asid_versions_eq(0, mmid, 0)) { + u64 newmmid = version | (mmid & mmid_mask); + + /* + * If our current MMID was active during a rollover, we + * can continue to use it and this was just a false alarm. + */ + if (check_update_reserved_mmid(mmid, newmmid)) { + mmid = newmmid; + goto set_context; + } + + /* + * We had a valid MMID in a previous life, so try to re-use + * it if possible. + */ + if (!__test_and_set_bit(mmid & mmid_mask, mmid_map)) { + mmid = newmmid; + goto set_context; + } + } + + /* Allocate a free MMID */ + mmid = find_next_zero_bit(mmid_map, num_mmids, cur_idx); + if (mmid != num_mmids) + goto reserve_mmid; + + /* We're out of MMIDs, so increment the global version */ + version = atomic64_add_return_relaxed(asid_first_version(0), + &mmid_version); + + /* Note currently active MMIDs & mark TLBs as requiring flushes */ + flush_context(); + + /* We have more MMIDs than CPUs, so this will always succeed */ + mmid = find_first_zero_bit(mmid_map, num_mmids); + +reserve_mmid: + __set_bit(mmid, mmid_map); + cur_idx = mmid; + mmid |= version; +set_context: + set_cpu_context(0, mm, mmid); + return mmid; +} + +void check_switch_mmu_context(struct mm_struct *mm) +{ + unsigned int cpu = smp_processor_id(); + u64 ctx, old_active_mmid; + unsigned long flags; + + if (!cpu_has_mmid) { + check_mmu_context(mm); + write_c0_entryhi(cpu_asid(cpu, mm)); + goto setup_pgd; + } + + /* + * MMID switch fast-path, to avoid acquiring cpu_mmid_lock when it's + * unnecessary. + * + * The memory ordering here is subtle. If our active_mmids is non-zero + * and the MMID matches the current version, then we update the CPU's + * asid_cache with a relaxed cmpxchg. Racing with a concurrent rollover + * means that either: + * + * - We get a zero back from the cmpxchg and end up waiting on + * cpu_mmid_lock in check_mmu_context(). Taking the lock synchronises + * with the rollover and so we are forced to see the updated + * generation. + * + * - We get a valid MMID back from the cmpxchg, which means the + * relaxed xchg in flush_context will treat us as reserved + * because atomic RmWs are totally ordered for a given location. + */ + ctx = cpu_context(cpu, mm); + old_active_mmid = READ_ONCE(cpu_data[cpu].asid_cache); + if (!old_active_mmid || + !asid_versions_eq(cpu, ctx, atomic64_read(&mmid_version)) || + !cmpxchg_relaxed(&cpu_data[cpu].asid_cache, old_active_mmid, ctx)) { + raw_spin_lock_irqsave(&cpu_mmid_lock, flags); + + ctx = cpu_context(cpu, mm); + if (!asid_versions_eq(cpu, ctx, atomic64_read(&mmid_version))) + ctx = get_new_mmid(mm); + + WRITE_ONCE(cpu_data[cpu].asid_cache, ctx); + raw_spin_unlock_irqrestore(&cpu_mmid_lock, flags); + } + + /* + * Invalidate the local TLB if needed. Note that we must only clear our + * bit in tlb_flush_pending after this is complete, so that the + * cpu_has_shared_ftlb_entries case below isn't misled. + */ + if (cpumask_test_cpu(cpu, &tlb_flush_pending)) { + if (cpu_has_vtag_icache) + flush_icache_all(); + local_flush_tlb_all(); + cpumask_clear_cpu(cpu, &tlb_flush_pending); + } + + write_c0_memorymapid(ctx & cpu_asid_mask(&boot_cpu_data)); + + /* + * If this CPU shares FTLB entries with its siblings and one or more of + * those siblings hasn't yet invalidated its TLB following a version + * increase then we need to invalidate any TLB entries for our MMID + * that we might otherwise pick up from a sibling. + * + * We ifdef on CONFIG_SMP because cpu_sibling_map isn't defined in + * CONFIG_SMP=n kernels. + */ +#ifdef CONFIG_SMP + if (cpu_has_shared_ftlb_entries && + cpumask_intersects(&tlb_flush_pending, &cpu_sibling_map[cpu])) { + /* Ensure we operate on the new MMID */ + mtc0_tlbw_hazard(); + + /* + * Invalidate all TLB entries associated with the new + * MMID, and wait for the invalidation to complete. + */ + ginvt_mmid(); + sync_ginv(); + } +#endif + +setup_pgd: + TLBMISS_HANDLER_SETUP_PGD(mm->pgd); +} +EXPORT_SYMBOL_GPL(check_switch_mmu_context); + +static int mmid_init(void) +{ + if (!cpu_has_mmid) + return 0; + + /* + * Expect allocation after rollover to fail if we don't have at least + * one more MMID than CPUs. + */ + num_mmids = asid_first_version(0); + WARN_ON(num_mmids <= num_possible_cpus()); + + atomic64_set(&mmid_version, asid_first_version(0)); + mmid_map = bitmap_zalloc(num_mmids, GFP_KERNEL); + if (!mmid_map) + panic("Failed to allocate bitmap for %u MMIDs\n", num_mmids); + + /* Reserve an MMID for kmap/wired entries */ + __set_bit(MMID_KERNEL_WIRED, mmid_map); + + pr_info("MMID allocator initialised with %u entries\n", num_mmids); + return 0; +} +early_initcall(mmid_init); -- cgit v1.3.1