linux-kernel - [PATCH v6 02/10] mm/hugetlb: Add a macro to get HUGETLB page sizes for mmap

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Date:   Tue, 30 Mar 2021 16:08:48 +0800
From:   Yanan Wang <wangyanan55@...wei.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Andrew Jones <drjones@...hat.com>, <kvm@...r.kernel.org>,
        <linux-kselftest@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     Ben Gardon <bgardon@...gle.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Peter Xu <peterx@...hat.com>, "Ingo Molnar" <mingo@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Arnd Bergmann <arnd@...db.de>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        <wanghaibin.wang@...wei.com>, <yuzenghui@...wei.com>,
        Yanan Wang <wangyanan55@...wei.com>
Subject: [PATCH v6 02/10] mm/hugetlb: Add a macro to get HUGETLB page sizes for mmap

We know that if a system supports multiple hugetlb page sizes,
the desired hugetlb page size can be specified in bits [26:31]
of the mmap() flag arguments. The value in these 6 bits will be
the shift of each hugetlb page size.

So add a macro to get the page size shift and then calculate the
corresponding hugetlb page size, using flag x.

Cc: Ben Gardon <bgardon@...gle.com>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: Michael Kerrisk <mtk.manpages@...il.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Suggested-by: Ben Gardon <bgardon@...gle.com>
Signed-off-by: Yanan Wang <wangyanan55@...wei.com>
Reviewed-by: Ben Gardon <bgardon@...gle.com>
---
 include/uapi/linux/mman.h       | 2 ++
 tools/include/uapi/linux/mman.h | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/include/uapi/linux/mman.h b/include/uapi/linux/mman.h
index f55bc680b5b0..d72df73b182d 100644
--- a/include/uapi/linux/mman.h
+++ b/include/uapi/linux/mman.h
@@ -41,4 +41,6 @@
 #define MAP_HUGE_2GB	HUGETLB_FLAG_ENCODE_2GB
 #define MAP_HUGE_16GB	HUGETLB_FLAG_ENCODE_16GB
 
+#define MAP_HUGE_PAGE_SIZE(x) (1ULL << ((x >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK))
+
 #endif /* _UAPI_LINUX_MMAN_H */
diff --git a/tools/include/uapi/linux/mman.h b/tools/include/uapi/linux/mman.h
index f55bc680b5b0..d72df73b182d 100644
--- a/tools/include/uapi/linux/mman.h
+++ b/tools/include/uapi/linux/mman.h
@@ -41,4 +41,6 @@
 #define MAP_HUGE_2GB	HUGETLB_FLAG_ENCODE_2GB
 #define MAP_HUGE_16GB	HUGETLB_FLAG_ENCODE_16GB
 
+#define MAP_HUGE_PAGE_SIZE(x) (1ULL << ((x >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK))
+
 #endif /* _UAPI_LINUX_MMAN_H */
-- 
2.19.1