Messages in this thread Patch in this message | | | Subject | Re: [PATCH] ubsan: don't handle misaligned address when support unaligned access | From | Ding Tianhong <> | Date | Fri, 1 Dec 2017 20:37:09 +0800 |
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On 2017/12/1 19:47, David Laight wrote: >> of noise in the log and cause confusion. >> >> This patch will close the detection of unaligned access when >> the system support unaligned access. >> >> Signed-off-by: Ding Tianhong <dingtianhong@huawei.com> >> --- >> lib/ubsan.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/lib/ubsan.c b/lib/ubsan.c >> index fb0409d..278b4c3 100644 >> --- a/lib/ubsan.c >> +++ b/lib/ubsan.c >> @@ -321,7 +321,8 @@ void __ubsan_handle_type_mismatch(struct type_mismatch_data *data, >> >> if (!ptr) >> handle_null_ptr_deref(data); >> - else if (data->alignment && !IS_ALIGNED(ptr, data->alignment)) >> + else if (data->alignment && !IS_ALIGNED(ptr, data->alignment) && >> + !IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) >> handle_missaligned_access(data, ptr); >> else >> handle_object_size_mismatch(data, ptr); > > Won't that report an object size error instead of actually > doing the required access? >
Yes,I miss it.
> Surely it shouldn't get into this function at all? > > I guess 'alignment' is set to 4 or 8. > If it were set to 3 or 7 (or 0) then the tests on the pointer > would be much simpler - maybe at a slight extra cost in setup. >
Looks like we need to fix it in the handle_missaligned_access:
diff --git a/lib/ubsan.c b/lib/ubsan.c index 278b4c3..040f8b2 100644 --- a/lib/ubsan.c +++ b/lib/ubsan.c @@ -289,6 +289,9 @@ static void handle_missaligned_access(struct type_mismatch_data *data, if (suppress_report(&data->location)) return;
+ if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) + return; + ubsan_prologue(&data->location, &flags);
pr_err("%s misaligned address %p for type %s\n",
Thanks Ding
> David >
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