[PATCH 4.9 79/92] include/linux/pfn_t.h: force ~ to be parsed as an unary operator

From: Greg Kroah-Hartman
Date: Thu Nov 29 2018 - 09:23:36 EST

4.9-stable review patch. If anyone has any objections, please let me know.


From: Sebastien Boisvert <sebhtml@xxxxxxxxxxxxxxx>

commit 4d54954a197175c0dcb3c82af0c0740d0c5f827a upstream.

Tracing the event "fs_dax:dax_pmd_insert_mapping" with perf produces this

[fs_dax:dax_pmd_insert_mapping] unknown op '~'

It is printed in process_op (tools/lib/traceevent/event-parse.c) because
'~' is parsed as a binary operator.

perf reads the format of fs_dax:dax_pmd_insert_mapping ("print fmt") from
/sys/kernel/debug/tracing/events/fs_dax/dax_pmd_insert_mapping/format .

The format contains:

~(((u64) ~(~(((1UL) << 12)-1)))
\ interpreted as a binary operator by process_op().

This part is generated in the declaration of the event class
dax_pmd_insert_mapping_class in include/trace/events/fs_dax.h :

__print_flags_u64(__entry->pfn_val & PFN_FLAGS_MASK, "|",

This patch adds a pair of parentheses in the declaration of PFN_FLAGS_MASK
to make sure that '~' is parsed as a unary operator by perf.

The part of the format that was problematic is now:

~(((u64) (~(~(((1UL) << 12)-1))))

Now, all the '~' are parsed as unary operators.

Link: http://lkml.kernel.org/r/20181021145939.8760-1-sebhtml@xxxxxxxxxxxxxxx
Signed-off-by: Sebastien Boisvert <sebhtml@xxxxxxxxxxxxxxx>
Acked-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@xxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Ross Zwisler <zwisler@xxxxxxxxxx>
Cc: Elenie Godzaridis <arangradient@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

include/linux/pfn_t.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/include/linux/pfn_t.h
+++ b/include/linux/pfn_t.h
@@ -9,7 +9,7 @@
* PFN_DEV - pfn is not covered by system memmap by default
* PFN_MAP - pfn has a dynamic page mapping established by a device driver
#define PFN_SG_LAST (1ULL << (BITS_PER_LONG_LONG - 2))
#define PFN_DEV (1ULL << (BITS_PER_LONG_LONG - 3))