linux-kernel - [PATCH v4 1/5] mm: Define VM

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Message-ID: <2f3d000794fb8ba269ecd99255ce0974ec29b144.1725278148.git.christophe.leroy@csgroup.eu>
Date: Mon,  2 Sep 2024 14:04:38 +0200
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Andrew Morton <akpm@...ux-foundation.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Michael Ellerman <mpe@...erman.id.au>,
	Nicholas Piggin <npiggin@...il.com>,
	Naveen N Rao <naveen@...nel.org>,
	Nathan Chancellor <nathan@...nel.org>,
	Nick Desaulniers <ndesaulniers@...gle.com>,
	Bill Wendling <morbo@...gle.com>,
	Justin Stitt <justinstitt@...gle.com>,
	Shuah Khan <shuah@...nel.org>,
	"Jason A . Donenfeld" <Jason@...c4.com>
Cc: Christophe Leroy <christophe.leroy@...roup.eu>,
	linux-kernel@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org,
	linux-kselftest@...r.kernel.org,
	llvm@...ts.linux.dev,
	linux-fsdevel@...r.kernel.org,
	linux-mm@...ck.org,
	linux-trace-kernel@...r.kernel.org,
	Adhemerval Zanella <adhemerval.zanella@...aro.org>,
	Xi Ruoyao <xry111@...111.site>
Subject: [PATCH v4 1/5] mm: Define VM_DROPPABLE for powerpc/32

Commit 9651fcedf7b9 ("mm: add MAP_DROPPABLE for designating always
lazily freeable mappings") only adds VM_DROPPABLE for 64 bits
architectures.

In order to also use the getrandom vDSO implementation on powerpc/32,
use VM_ARCH_1 for VM_DROPPABLE on powerpc/32. This is possible because
VM_ARCH_1 is used for VM_SAO on powerpc and VM_SAO is only for
powerpc/64. It is used in combination with PROT_SAO in some parts of
code that are restricted to CONFIG_PPC64 through #ifdefs, it is
therefore possible to define VM_SAO for CONFIG_PPC64 only.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
v4: Added more details in commit message following comment from Michael.
v3: Fixed build failure reported by robots.
---
 fs/proc/task_mmu.c             | 4 +++-
 include/linux/mm.h             | 4 +++-
 include/trace/events/mmflags.h | 4 ++--
 3 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 5f171ad7b436..3a07e13e2f81 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -987,8 +987,10 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma)
 #ifdef CONFIG_X86_USER_SHADOW_STACK
 		[ilog2(VM_SHADOW_STACK)] = "ss",
 #endif
-#ifdef CONFIG_64BIT
+#if defined(CONFIG_64BIT) || defined(CONFIG_PPC32)
 		[ilog2(VM_DROPPABLE)] = "dp",
+#endif
+#ifdef CONFIG_64BIT
 		[ilog2(VM_SEALED)] = "sl",
 #endif
 	};
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 6549d0979b28..028847f39442 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -359,7 +359,7 @@ extern unsigned int kobjsize(const void *objp);
 
 #if defined(CONFIG_X86)
 # define VM_PAT		VM_ARCH_1	/* PAT reserves whole VMA at once (x86) */
-#elif defined(CONFIG_PPC)
+#elif defined(CONFIG_PPC64)
 # define VM_SAO		VM_ARCH_1	/* Strong Access Ordering (powerpc) */
 #elif defined(CONFIG_PARISC)
 # define VM_GROWSUP	VM_ARCH_1
@@ -409,6 +409,8 @@ extern unsigned int kobjsize(const void *objp);
 #ifdef CONFIG_64BIT
 #define VM_DROPPABLE_BIT	40
 #define VM_DROPPABLE		BIT(VM_DROPPABLE_BIT)
+#elif defined(CONFIG_PPC32)
+#define VM_DROPPABLE		VM_ARCH_1
 #else
 #define VM_DROPPABLE		VM_NONE
 #endif
diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h
index b63d211bd141..37265977d524 100644
--- a/include/trace/events/mmflags.h
+++ b/include/trace/events/mmflags.h
@@ -143,7 +143,7 @@ IF_HAVE_PG_ARCH_X(arch_3)
 
 #if defined(CONFIG_X86)
 #define __VM_ARCH_SPECIFIC_1 {VM_PAT,     "pat"           }
-#elif defined(CONFIG_PPC)
+#elif defined(CONFIG_PPC64)
 #define __VM_ARCH_SPECIFIC_1 {VM_SAO,     "sao"           }
 #elif defined(CONFIG_PARISC)
 #define __VM_ARCH_SPECIFIC_1 {VM_GROWSUP,	"growsup"	}
@@ -165,7 +165,7 @@ IF_HAVE_PG_ARCH_X(arch_3)
 # define IF_HAVE_UFFD_MINOR(flag, name)
 #endif
 
-#ifdef CONFIG_64BIT
+#if defined(CONFIG_64BIT) || defined(CONFIG_PPC32)
 # define IF_HAVE_VM_DROPPABLE(flag, name) {flag, name},
 #else
 # define IF_HAVE_VM_DROPPABLE(flag, name)
-- 
2.44.0