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

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Date:   Thu, 29 Nov 2018 15:12:48 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Sebastien Boisvert <sebhtml@...eotron.qc.ca>,
        Dan Williams <dan.j.williams@...el.com>,
        "Steven Rostedt (VMware)" <rostedt@...dmis.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@...il.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Ross Zwisler <zwisler@...nel.org>,
        Elenie Godzaridis <arangradient@...il.com>,
        stable@...r.kerenl.org, Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.9 79/92] include/linux/pfn_t.h: force ~ to be parsed as an unary operator

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

------------------

From: Sebastien Boisvert <sebhtml@...eotron.qc.ca>

commit 4d54954a197175c0dcb3c82af0c0740d0c5f827a upstream.

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

      [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, "|",
			PFN_FLAGS_TRACE),

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@videotron.qc.ca
Signed-off-by: Sebastien Boisvert <sebhtml@...eotron.qc.ca>
Acked-by: Dan Williams <dan.j.williams@...el.com>
Cc: "Steven Rostedt (VMware)" <rostedt@...dmis.org>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@...il.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Ross Zwisler <zwisler@...nel.org>
Cc: Elenie Godzaridis <arangradient@...il.com>
Cc: <stable@...r.kerenl.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 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_FLAGS_MASK (((u64) ~PAGE_MASK) << (BITS_PER_LONG_LONG - PAGE_SHIFT))
+#define PFN_FLAGS_MASK (((u64) (~PAGE_MASK)) << (BITS_PER_LONG_LONG - PAGE_SHIFT))
 #define PFN_SG_CHAIN (1ULL << (BITS_PER_LONG_LONG - 1))
 #define PFN_SG_LAST (1ULL << (BITS_PER_LONG_LONG - 2))
 #define PFN_DEV (1ULL << (BITS_PER_LONG_LONG - 3))