[PATCH v5 06/25] mm: Add PG_ARCH_2 page flag

Catalin Marinas
2020-06-24T17:53:02Z

From: Steven Price <steven.price@arm.com>

For arm64 MTE support it is necessary to be able to mark pages that
contain user space visible tags that will need to be saved/restored e.g.
when swapped out.

To support this add a new arch specific flag (PG_ARCH_2) that arch code
can opt into using ARCH_USES_PG_ARCH_2.

Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
---

Notes:
New in v4.

fs/proc/page.c | 3 +++
include/linux/kernel-page-flags.h | 1 +
include/linux/page-flags.h | 3 +++
include/trace/events/mmflags.h | 9 ++++++++-
mm/Kconfig | 3 +++
tools/vm/page-types.c | 2 ++
6 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/fs/proc/page.c b/fs/proc/page.c
index f909243d4a66..1b6cbe0849a8 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -217,6 +217,9 @@ u64 stable_page_flags(struct page *page)
u |= kpf_copy_bit(k, KPF_PRIVATE_2, PG_private_2);
u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE, PG_owner_priv_1);
u |= kpf_copy_bit(k, KPF_ARCH, PG_arch_1);
+#ifdef CONFIG_ARCH_USES_PG_ARCH_2
+ u |= kpf_copy_bit(k, KPF_ARCH_2, PG_arch_2);
+#endif

return u;
};
diff --git a/include/linux/kernel-page-flags.h b/include/linux/kernel-page-flags.h
index abd20ef93c98..eee1877a354e 100644
--- a/include/linux/kernel-page-flags.h
+++ b/include/linux/kernel-page-flags.h
@@ -17,5 +17,6 @@
#define KPF_ARCH 38
#define KPF_UNCACHED 39
#define KPF_SOFTDIRTY 40
+#define KPF_ARCH_2 41

#endif /* LINUX_KERNEL_PAGE_FLAGS_H */
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 6be1aa559b1e..b40d7cb7c8e6 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -135,6 +135,9 @@ enum pageflags {
#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
PG_young,
PG_idle,
+#endif
+#ifdef CONFIG_ARCH_USES_PG_ARCH_2
+ PG_arch_2,
#endif
__NR_PAGEFLAGS,

diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h
index 5fb752034386..5d098029a2d8 100644
--- a/include/trace/events/mmflags.h
+++ b/include/trace/events/mmflags.h
@@ -79,6 +79,12 @@
#define IF_HAVE_PG_IDLE(flag,string)
#endif

+#ifdef CONFIG_ARCH_USES_PG_ARCH_2
+#define IF_HAVE_PG_ARCH_2(flag,string) ,{1UL << flag, string}
+#else
+#define IF_HAVE_PG_ARCH_2(flag,string)
+#endif
+
#define __def_pageflag_names \
{1UL << PG_locked, "locked" }, \
{1UL << PG_waiters, "waiters" }, \
@@ -105,7 +111,8 @@ IF_HAVE_PG_MLOCK(PG_mlocked, "mlocked" ) \
IF_HAVE_PG_UNCACHED(PG_uncached, "uncached" ) \
IF_HAVE_PG_HWPOISON(PG_hwpoison, "hwpoison" ) \
IF_HAVE_PG_IDLE(PG_young, "young" ) \
-IF_HAVE_PG_IDLE(PG_idle, "idle" )
+IF_HAVE_PG_IDLE(PG_idle, "idle" ) \
+IF_HAVE_PG_ARCH_2(PG_arch_2, "arch_2" )

#define show_page_flags(flags) \
(flags) ? __print_flags(flags, "|", \
diff --git a/mm/Kconfig b/mm/Kconfig
index f2104cc0d35c..21eddae15078 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -872,4 +872,7 @@ config ARCH_HAS_HUGEPD
config MAPPING_DIRTY_HELPERS
bool

+config ARCH_USES_PG_ARCH_2
+ bool
+
endmenu
diff --git a/tools/vm/page-types.c b/tools/vm/page-types.c
index 58c0eab71bca..0517c744b04e 100644
--- a/tools/vm/page-types.c
+++ b/tools/vm/page-types.c
@@ -78,6 +78,7 @@
#define KPF_ARCH 38
#define KPF_UNCACHED 39
#define KPF_SOFTDIRTY 40
+#define KPF_ARCH_2 41

/* [48-] take some arbitrary free slots for expanding overloaded flags
* not part of kernel API
@@ -135,6 +136,7 @@ static const char * const page_flag_names[] = {
[KPF_ARCH] = "h:arch",
[KPF_UNCACHED] = "c:uncached",
[KPF_SOFTDIRTY] = "f:softdirty",
+ [KPF_ARCH_2] = "H:arch_2",

[KPF_READAHEAD] = "I:readahead",
[KPF_SLOB_FREE] = "P:slob_free",