Re: [RFC PATCH v4 2/9] tools headers: Add a macro to get HUGETLB page sizes for mmap

On 2021/3/12 19:14, Andrew Jones wrote:

On Tue, Mar 02, 2021 at 08:57:44PM +0800, Yanan Wang wrote:

quoted

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 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 <redacted>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <redacted>
Cc: Arnaldo Carvalho de Melo <redacted>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Michael Kerrisk <redacted>
Cc: Thomas Gleixner <redacted>
Suggested-by: Ben Gardon <redacted>
Signed-off-by: Yanan Wang <redacted>
Reviewed-by: Ben Gardon <redacted>
---
  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..8bd41128a0ee 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) (1 << ((x >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK))

Needs to be '1ULL' to avoid shift overflow when given MAP_HUGE_16GB.

Thanks, drew. Will fix it.

Thanks,
drew

quoted

+
  #endif /* _UAPI_LINUX_MMAN_H */

diff --git a/tools/include/uapi/linux/mman.h b/tools/include/uapi/linux/mman.h
index f55bc680b5b0..8bd41128a0ee 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) (1 << ((x >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK))
+
  #endif /* _UAPI_LINUX_MMAN_H */

-- 
2.23.0

.