On Thu, 10 Oct 2019 18:36:16 +0200 Sebastian Andrzej Siewior <[email protected]> wrote:
Hi, you seem to be me missing the "From:" line here, to keep Julien as the author. If you have this patch in a git repo, you could use: $ git commit --amend --author "Julien Grall <[email protected]>" so that git keeps the authorship, which should be translated into the proper email form (From: ...) by git send-email. And what is the reason for the repost anyway? Cheers, Andre. > At the moment, UBSAN report will be serialized using a spin_lock(). On > RT-systems, spinlocks are turned to rt_spin_lock and may sleep. This will > result to the following splat if the undefined behavior is in a context > that can not sleep: > > | BUG: sleeping function called from invalid context at > kernel/locking/rtmutex.c:968 > | in_atomic(): 1, irqs_disabled(): 128, pid: 3447, name: make > | 1 lock held by make/3447: > | #0: 000000009a966332 (&mm->mmap_sem){++++}, at: do_page_fault+0x140/0x4f8 > | Preemption disabled at: > | [<ffff000011324a4c>] rt_mutex_futex_unlock+0x4c/0xb0 > | CPU: 3 PID: 3447 Comm: make Tainted: G W > 5.2.14-rt7-01890-ge6e057589653 #911 > | Call trace: > … > | ___might_sleep+0x154/0x210 > | rt_spin_lock+0x68/0xa0 > | ubsan_prologue+0x30/0x68 > | handle_overflow+0x64/0xe0 > | __ubsan_handle_add_overflow+0x10/0x18 > > The spin_lock() will protect against multiple CPUs to output a report > together, I guess to prevent them to be interleaved. However, they can > still interleave with other messages (and even splat from __migth_sleep). > > So the lock usefulness seems pretty limited. Rather than trying to > accomodate RT-system by switching to a raw_spin_lock(), the lock is now > completely dropped. > > Link: https://lkml.kernel.org/r/[email protected] > Reported-by: Andre Przywara <[email protected]> > Signed-off-by: > Acked-by: Andrey Ryabinin <[email protected]> > Signed-off-by: Sebastian Andrzej Siewior <[email protected]> > --- > Repost of > https://lkml.kernel.org/r/[email protected] > > lib/ubsan.c | 64 +++++++++++++++++++---------------------------------- > 1 file changed, 23 insertions(+), 41 deletions(-) > > diff --git a/lib/ubsan.c b/lib/ubsan.c > index e7d31735950de..39d5952c42733 100644 > --- a/lib/ubsan.c > +++ b/lib/ubsan.c > @@ -140,25 +140,21 @@ static void val_to_string(char *str, size_t size, > struct type_descriptor *type, > } > } > > -static DEFINE_SPINLOCK(report_lock); > - > -static void ubsan_prologue(struct source_location *location, > - unsigned long *flags) > +static void ubsan_prologue(struct source_location *location) > { > current->in_ubsan++; > - spin_lock_irqsave(&report_lock, *flags); > > pr_err("========================================" > "========================================\n"); > print_source_location("UBSAN: Undefined behaviour in", location); > } > > -static void ubsan_epilogue(unsigned long *flags) > +static void ubsan_epilogue(void) > { > dump_stack(); > pr_err("========================================" > "========================================\n"); > - spin_unlock_irqrestore(&report_lock, *flags); > + > current->in_ubsan--; > } > > @@ -167,14 +163,13 @@ static void handle_overflow(struct overflow_data *data, > void *lhs, > { > > struct type_descriptor *type = data->type; > - unsigned long flags; > char lhs_val_str[VALUE_LENGTH]; > char rhs_val_str[VALUE_LENGTH]; > > if (suppress_report(&data->location)) > return; > > - ubsan_prologue(&data->location, &flags); > + ubsan_prologue(&data->location); > > val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs); > val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs); > @@ -186,7 +181,7 @@ static void handle_overflow(struct overflow_data *data, > void *lhs, > rhs_val_str, > type->type_name); > > - ubsan_epilogue(&flags); > + ubsan_epilogue(); > } > > void __ubsan_handle_add_overflow(struct overflow_data *data, > @@ -214,20 +209,19 @@ EXPORT_SYMBOL(__ubsan_handle_mul_overflow); > void __ubsan_handle_negate_overflow(struct overflow_data *data, > void *old_val) > { > - unsigned long flags; > char old_val_str[VALUE_LENGTH]; > > if (suppress_report(&data->location)) > return; > > - ubsan_prologue(&data->location, &flags); > + ubsan_prologue(&data->location); > > val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val); > > pr_err("negation of %s cannot be represented in type %s:\n", > old_val_str, data->type->type_name); > > - ubsan_epilogue(&flags); > + ubsan_epilogue(); > } > EXPORT_SYMBOL(__ubsan_handle_negate_overflow); > > @@ -235,13 +229,12 @@ EXPORT_SYMBOL(__ubsan_handle_negate_overflow); > void __ubsan_handle_divrem_overflow(struct overflow_data *data, > void *lhs, void *rhs) > { > - unsigned long flags; > char rhs_val_str[VALUE_LENGTH]; > > if (suppress_report(&data->location)) > return; > > - ubsan_prologue(&data->location, &flags); > + ubsan_prologue(&data->location); > > val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs); > > @@ -251,58 +244,52 @@ void __ubsan_handle_divrem_overflow(struct > overflow_data *data, > else > pr_err("division by zero\n"); > > - ubsan_epilogue(&flags); > + ubsan_epilogue(); > } > EXPORT_SYMBOL(__ubsan_handle_divrem_overflow); > > static void handle_null_ptr_deref(struct type_mismatch_data_common *data) > { > - unsigned long flags; > - > if (suppress_report(data->location)) > return; > > - ubsan_prologue(data->location, &flags); > + ubsan_prologue(data->location); > > pr_err("%s null pointer of type %s\n", > type_check_kinds[data->type_check_kind], > data->type->type_name); > > - ubsan_epilogue(&flags); > + ubsan_epilogue(); > } > > static void handle_misaligned_access(struct type_mismatch_data_common *data, > unsigned long ptr) > { > - unsigned long flags; > - > if (suppress_report(data->location)) > return; > > - ubsan_prologue(data->location, &flags); > + ubsan_prologue(data->location); > > pr_err("%s misaligned address %p for type %s\n", > type_check_kinds[data->type_check_kind], > (void *)ptr, data->type->type_name); > pr_err("which requires %ld byte alignment\n", data->alignment); > > - ubsan_epilogue(&flags); > + ubsan_epilogue(); > } > > static void handle_object_size_mismatch(struct type_mismatch_data_common > *data, > unsigned long ptr) > { > - unsigned long flags; > - > if (suppress_report(data->location)) > return; > > - ubsan_prologue(data->location, &flags); > + ubsan_prologue(data->location); > pr_err("%s address %p with insufficient space\n", > type_check_kinds[data->type_check_kind], > (void *) ptr); > pr_err("for an object of type %s\n", data->type->type_name); > - ubsan_epilogue(&flags); > + ubsan_epilogue(); > } > > static void ubsan_type_mismatch_common(struct type_mismatch_data_common > *data, > @@ -351,25 +338,23 @@ EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1); > > void __ubsan_handle_out_of_bounds(struct out_of_bounds_data *data, void > *index) > { > - unsigned long flags; > char index_str[VALUE_LENGTH]; > > if (suppress_report(&data->location)) > return; > > - ubsan_prologue(&data->location, &flags); > + ubsan_prologue(&data->location); > > val_to_string(index_str, sizeof(index_str), data->index_type, index); > pr_err("index %s is out of range for type %s\n", index_str, > data->array_type->type_name); > - ubsan_epilogue(&flags); > + ubsan_epilogue(); > } > EXPORT_SYMBOL(__ubsan_handle_out_of_bounds); > > void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data > *data, > void *lhs, void *rhs) > { > - unsigned long flags; > struct type_descriptor *rhs_type = data->rhs_type; > struct type_descriptor *lhs_type = data->lhs_type; > char rhs_str[VALUE_LENGTH]; > @@ -378,7 +363,7 @@ void __ubsan_handle_shift_out_of_bounds(struct > shift_out_of_bounds_data *data, > if (suppress_report(&data->location)) > return; > > - ubsan_prologue(&data->location, &flags); > + ubsan_prologue(&data->location); > > val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs); > val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs); > @@ -401,18 +386,16 @@ void __ubsan_handle_shift_out_of_bounds(struct > shift_out_of_bounds_data *data, > lhs_str, rhs_str, > lhs_type->type_name); > > - ubsan_epilogue(&flags); > + ubsan_epilogue(); > } > EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds); > > > void __ubsan_handle_builtin_unreachable(struct unreachable_data *data) > { > - unsigned long flags; > - > - ubsan_prologue(&data->location, &flags); > + ubsan_prologue(&data->location); > pr_err("calling __builtin_unreachable()\n"); > - ubsan_epilogue(&flags); > + ubsan_epilogue(); > panic("can't return from __builtin_unreachable()"); > } > EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable); > @@ -420,19 +403,18 @@ EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable); > void __ubsan_handle_load_invalid_value(struct invalid_value_data *data, > void *val) > { > - unsigned long flags; > char val_str[VALUE_LENGTH]; > > if (suppress_report(&data->location)) > return; > > - ubsan_prologue(&data->location, &flags); > + ubsan_prologue(&data->location); > > val_to_string(val_str, sizeof(val_str), data->type, val); > > pr_err("load of value %s is not a valid value for type %s\n", > val_str, data->type->type_name); > > - ubsan_epilogue(&flags); > + ubsan_epilogue(); > } > EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);
