mm: kmsan: remove runtime checks from kmsan_unpoison_memory()
Similarly to what's been done in commit85716a80c1
("kmsan: allow using __msan_instrument_asm_store() inside runtime"), it should be safe to call kmsan_unpoison_memory() from within the runtime, as it does not allocate memory or take locks. Remove the redundant runtime checks. This should fix false positives seen with CONFIG_DEBUG_LIST=y when the non-instrumented lib/stackdepot.c failed to unpoison the memory chunks later checked by the instrumented lib/list_debug.c Also replace the implementation of kmsan_unpoison_entry_regs() with a call to kmsan_unpoison_memory(). Link: https://lkml.kernel.org/r/20240124173134.1165747-1-glider@google.com Fixes:f80be4571b
("kmsan: add KMSAN runtime core") Signed-off-by: Alexander Potapenko <glider@google.com> Tested-by: Marco Elver <elver@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Ilya Leoshkevich <iii@linux.ibm.com> Cc: Nicholas Miehlbradt <nicholas@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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@ -359,6 +359,12 @@ void kmsan_handle_dma_sg(struct scatterlist *sg, int nents,
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}
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}
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/* Functions from kmsan-checks.h follow. */
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/* Functions from kmsan-checks.h follow. */
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/*
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* To create an origin, kmsan_poison_memory() unwinds the stacks and stores it
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* into the stack depot. This may cause deadlocks if done from within KMSAN
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* runtime, therefore we bail out if kmsan_in_runtime().
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*/
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void kmsan_poison_memory(const void *address, size_t size, gfp_t flags)
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void kmsan_poison_memory(const void *address, size_t size, gfp_t flags)
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{
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{
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if (!kmsan_enabled || kmsan_in_runtime())
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if (!kmsan_enabled || kmsan_in_runtime())
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@ -371,37 +377,11 @@ void kmsan_poison_memory(const void *address, size_t size, gfp_t flags)
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}
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}
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EXPORT_SYMBOL(kmsan_poison_memory);
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EXPORT_SYMBOL(kmsan_poison_memory);
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void kmsan_unpoison_memory(const void *address, size_t size)
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{
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unsigned long ua_flags;
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if (!kmsan_enabled || kmsan_in_runtime())
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return;
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ua_flags = user_access_save();
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kmsan_enter_runtime();
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/* The users may want to poison/unpoison random memory. */
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kmsan_internal_unpoison_memory((void *)address, size,
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KMSAN_POISON_NOCHECK);
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kmsan_leave_runtime();
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user_access_restore(ua_flags);
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}
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EXPORT_SYMBOL(kmsan_unpoison_memory);
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/*
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/*
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* Version of kmsan_unpoison_memory() that can be called from within the KMSAN
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* Unlike kmsan_poison_memory(), this function can be used from within KMSAN
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* runtime.
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* runtime, because it does not trigger allocations or call instrumented code.
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*
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* Non-instrumented IRQ entry functions receive struct pt_regs from assembly
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* code. Those regs need to be unpoisoned, otherwise using them will result in
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* false positives.
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* Using kmsan_unpoison_memory() is not an option in entry code, because the
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* return value of in_task() is inconsistent - as a result, certain calls to
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* kmsan_unpoison_memory() are ignored. kmsan_unpoison_entry_regs() ensures that
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* the registers are unpoisoned even if kmsan_in_runtime() is true in the early
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* entry code.
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*/
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*/
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void kmsan_unpoison_entry_regs(const struct pt_regs *regs)
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void kmsan_unpoison_memory(const void *address, size_t size)
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{
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{
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unsigned long ua_flags;
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unsigned long ua_flags;
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@ -409,10 +389,20 @@ void kmsan_unpoison_entry_regs(const struct pt_regs *regs)
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return;
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return;
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ua_flags = user_access_save();
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ua_flags = user_access_save();
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kmsan_internal_unpoison_memory((void *)regs, sizeof(*regs),
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/* The users may want to poison/unpoison random memory. */
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kmsan_internal_unpoison_memory((void *)address, size,
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KMSAN_POISON_NOCHECK);
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KMSAN_POISON_NOCHECK);
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user_access_restore(ua_flags);
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user_access_restore(ua_flags);
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}
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}
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EXPORT_SYMBOL(kmsan_unpoison_memory);
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/*
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* Version of kmsan_unpoison_memory() called from IRQ entry functions.
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*/
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void kmsan_unpoison_entry_regs(const struct pt_regs *regs)
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{
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kmsan_unpoison_memory((void *)regs, sizeof(*regs));
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}
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void kmsan_check_memory(const void *addr, size_t size)
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void kmsan_check_memory(const void *addr, size_t size)
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{
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{
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