| Message ID | 20211118081027.3175699-2-elver@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | kcsan: Support detecting a subset of missing memory barriers | expand |
On Thu, Nov 18, 2021 at 09:10:05AM +0100, Marco Elver wrote: > Factor out the switch statement reading instrumented memory into a > helper read_instrumented_memory(). > > No functional change. > > Signed-off-by: Marco Elver <elver@google.com> Nice cleanup! Acked-by: Mark Rutland <mark.rutland@arm.com> Mark. > --- > kernel/kcsan/core.c | 51 +++++++++++++++------------------------------ > 1 file changed, 17 insertions(+), 34 deletions(-) > > diff --git a/kernel/kcsan/core.c b/kernel/kcsan/core.c > index 4b84c8e7884b..6bfd3040f46b 100644 > --- a/kernel/kcsan/core.c > +++ b/kernel/kcsan/core.c > @@ -325,6 +325,21 @@ static void delay_access(int type) > udelay(delay); > } > > +/* > + * Reads the instrumented memory for value change detection; value change > + * detection is currently done for accesses up to a size of 8 bytes. > + */ > +static __always_inline u64 read_instrumented_memory(const volatile void *ptr, size_t size) > +{ > + switch (size) { > + case 1: return READ_ONCE(*(const u8 *)ptr); > + case 2: return READ_ONCE(*(const u16 *)ptr); > + case 4: return READ_ONCE(*(const u32 *)ptr); > + case 8: return READ_ONCE(*(const u64 *)ptr); > + default: return 0; /* Ignore; we do not diff the values. */ > + } > +} > + > void kcsan_save_irqtrace(struct task_struct *task) > { > #ifdef CONFIG_TRACE_IRQFLAGS > @@ -482,23 +497,7 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type, unsigned > * Read the current value, to later check and infer a race if the data > * was modified via a non-instrumented access, e.g. from a device. > */ > - old = 0; > - switch (size) { > - case 1: > - old = READ_ONCE(*(const u8 *)ptr); > - break; > - case 2: > - old = READ_ONCE(*(const u16 *)ptr); > - break; > - case 4: > - old = READ_ONCE(*(const u32 *)ptr); > - break; > - case 8: > - old = READ_ONCE(*(const u64 *)ptr); > - break; > - default: > - break; /* ignore; we do not diff the values */ > - } > + old = read_instrumented_memory(ptr, size); > > /* > * Delay this thread, to increase probability of observing a racy > @@ -511,23 +510,7 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type, unsigned > * racy access. > */ > access_mask = ctx->access_mask; > - new = 0; > - switch (size) { > - case 1: > - new = READ_ONCE(*(const u8 *)ptr); > - break; > - case 2: > - new = READ_ONCE(*(const u16 *)ptr); > - break; > - case 4: > - new = READ_ONCE(*(const u32 *)ptr); > - break; > - case 8: > - new = READ_ONCE(*(const u64 *)ptr); > - break; > - default: > - break; /* ignore; we do not diff the values */ > - } > + new = read_instrumented_memory(ptr, size); > > diff = old ^ new; > if (access_mask) > -- > 2.34.0.rc2.393.gf8c9666880-goog >
diff --git a/kernel/kcsan/core.c b/kernel/kcsan/core.c index 4b84c8e7884b..6bfd3040f46b 100644 --- a/kernel/kcsan/core.c +++ b/kernel/kcsan/core.c @@ -325,6 +325,21 @@ static void delay_access(int type) udelay(delay); } +/* + * Reads the instrumented memory for value change detection; value change + * detection is currently done for accesses up to a size of 8 bytes. + */ +static __always_inline u64 read_instrumented_memory(const volatile void *ptr, size_t size) +{ + switch (size) { + case 1: return READ_ONCE(*(const u8 *)ptr); + case 2: return READ_ONCE(*(const u16 *)ptr); + case 4: return READ_ONCE(*(const u32 *)ptr); + case 8: return READ_ONCE(*(const u64 *)ptr); + default: return 0; /* Ignore; we do not diff the values. */ + } +} + void kcsan_save_irqtrace(struct task_struct *task) { #ifdef CONFIG_TRACE_IRQFLAGS @@ -482,23 +497,7 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type, unsigned * Read the current value, to later check and infer a race if the data * was modified via a non-instrumented access, e.g. from a device. */ - old = 0; - switch (size) { - case 1: - old = READ_ONCE(*(const u8 *)ptr); - break; - case 2: - old = READ_ONCE(*(const u16 *)ptr); - break; - case 4: - old = READ_ONCE(*(const u32 *)ptr); - break; - case 8: - old = READ_ONCE(*(const u64 *)ptr); - break; - default: - break; /* ignore; we do not diff the values */ - } + old = read_instrumented_memory(ptr, size); /* * Delay this thread, to increase probability of observing a racy @@ -511,23 +510,7 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type, unsigned * racy access. */ access_mask = ctx->access_mask; - new = 0; - switch (size) { - case 1: - new = READ_ONCE(*(const u8 *)ptr); - break; - case 2: - new = READ_ONCE(*(const u16 *)ptr); - break; - case 4: - new = READ_ONCE(*(const u32 *)ptr); - break; - case 8: - new = READ_ONCE(*(const u64 *)ptr); - break; - default: - break; /* ignore; we do not diff the values */ - } + new = read_instrumented_memory(ptr, size); diff = old ^ new; if (access_mask)
Factor out the switch statement reading instrumented memory into a helper read_instrumented_memory(). No functional change. Signed-off-by: Marco Elver <elver@google.com> --- kernel/kcsan/core.c | 51 +++++++++++++++------------------------------ 1 file changed, 17 insertions(+), 34 deletions(-)