linux-kernel - [PATCH 1/1 fyi] tools headers: Synchronize {uapi/}linux/bits.h with the kernel sources

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Message-ID: <Zx-ZVH7bHqtFn8Dv@x1>
Date: Mon, 28 Oct 2024 11:01:56 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: Adrian Hunter <adrian.hunter@...el.com>,
	Anshuman Khandual <anshuman.khandual@....com>,
	Ian Rogers <irogers@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
	Kan Liang <kan.liang@...ux.intel.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Yury Norov <yury.norov@...il.com>
Subject: [PATCH 1/1 fyi] tools headers: Synchronize {uapi/}linux/bits.h with
 the kernel sources

tldr; Just FYI, I'm carrying this on the perf tools tree.

Full explanation:

There used to be no copies, with tools/ code using kernel headers
directly. From time to time tools/perf/ broke due to legitimate kernel
hacking. At some point Linus complained about such direct usage. Then we
adopted the current model.

See further details at:

 https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/include/uapi/README

To pick up the changes in this cset:

  947697c6f0f75f98 ("uapi: Define GENMASK_U128")

This addresses these perf build warnings:

  Warning: Kernel ABI header differences:
    diff -u tools/include/uapi/linux/bits.h include/uapi/linux/bits.h
    diff -u tools/include/linux/bits.h include/linux/bits.h

Please see tools/include/uapi/README for further details.

Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: Anshuman Khandual <anshuman.khandual@....com>
Cc: Ian Rogers <irogers@...gle.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Kan Liang <kan.liang@...ux.intel.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Yury Norov <yury.norov@...il.com>
Link: https://lore.kernel.org/lkml/
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/include/linux/bits.h      | 15 +++++++++++++++
 tools/include/uapi/linux/bits.h |  3 +++
 2 files changed, 18 insertions(+)

diff --git a/tools/include/linux/bits.h b/tools/include/linux/bits.h
index 0eb24d21aac2142c..60044b6088172b3f 100644
--- a/tools/include/linux/bits.h
+++ b/tools/include/linux/bits.h
@@ -36,4 +36,19 @@
 #define GENMASK_ULL(h, l) \
 	(GENMASK_INPUT_CHECK(h, l) + __GENMASK_ULL(h, l))
 
+#if !defined(__ASSEMBLY__)
+/*
+ * Missing asm support
+ *
+ * __GENMASK_U128() depends on _BIT128() which would not work
+ * in the asm code, as it shifts an 'unsigned __init128' data
+ * type instead of direct representation of 128 bit constants
+ * such as long and unsigned long. The fundamental problem is
+ * that a 128 bit constant will get silently truncated by the
+ * gcc compiler.
+ */
+#define GENMASK_U128(h, l) \
+	(GENMASK_INPUT_CHECK(h, l) + __GENMASK_U128(h, l))
+#endif
+
 #endif	/* __LINUX_BITS_H */
diff --git a/tools/include/uapi/linux/bits.h b/tools/include/uapi/linux/bits.h
index 3c2a101986a314f6..5ee30f882736cbd1 100644
--- a/tools/include/uapi/linux/bits.h
+++ b/tools/include/uapi/linux/bits.h
@@ -12,4 +12,7 @@
         (((~_ULL(0)) - (_ULL(1) << (l)) + 1) & \
          (~_ULL(0) >> (__BITS_PER_LONG_LONG - 1 - (h))))
 
+#define __GENMASK_U128(h, l) \
+	((_BIT128((h)) << 1) - (_BIT128(l)))
+
 #endif /* _UAPI_LINUX_BITS_H */
-- 
2.47.0