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From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	npiggin@gmail.com, dja@axtens.net
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	linux-mm@kvack.org
Subject: [PATCH v3 07/15] powerpc: align stack to 2 * THREAD_SIZE with VMAP_STACK
Date: Tue, 10 Sep 2019 09:16:26 +0000 (UTC)	[thread overview]
Message-ID: <4ddb131f8a1db7eb01b65dc057234c824e889dd3.1568106758.git.christophe.leroy@c-s.fr> (raw)
In-Reply-To: <cover.1568106758.git.christophe.leroy@c-s.fr>

In order to ease stack overflow detection, align
stack to 2 * THREAD_SIZE when using VMAP_STACK.
This allows overflow detection using a single bit check.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/include/asm/thread_info.h | 13 +++++++++++++
 arch/powerpc/kernel/setup_32.c         |  2 +-
 arch/powerpc/kernel/setup_64.c         |  2 +-
 arch/powerpc/kernel/vmlinux.lds.S      |  2 +-
 4 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h
index 488d5c4670ff..a2270749b282 100644
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -22,6 +22,19 @@
 
 #define THREAD_SIZE		(1 << THREAD_SHIFT)
 
+/*
+ * By aligning VMAP'd stacks to 2 * THREAD_SIZE, we can detect overflow by
+ * checking sp & (1 << THREAD_SHIFT), which we can do cheaply in the entry
+ * assembly.
+ */
+#ifdef CONFIG_VMAP_STACK
+#define THREAD_ALIGN_SHIFT	(THREAD_SHIFT + 1)
+#else
+#define THREAD_ALIGN_SHIFT	THREAD_SHIFT
+#endif
+
+#define THREAD_ALIGN		(1 << THREAD_ALIGN_SHIFT)
+
 #ifndef __ASSEMBLY__
 #include <linux/cache.h>
 #include <asm/processor.h>
diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index a7541edf0cdb..180e658c1a6b 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -137,7 +137,7 @@ arch_initcall(ppc_init);
 
 static void *__init alloc_stack(void)
 {
-	void *ptr = memblock_alloc(THREAD_SIZE, THREAD_SIZE);
+	void *ptr = memblock_alloc(THREAD_SIZE, THREAD_ALIGN);
 
 	if (!ptr)
 		panic("cannot allocate %d bytes for stack at %pS\n",
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 44b4c432a273..f630fe4d36a8 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -644,7 +644,7 @@ static void *__init alloc_stack(unsigned long limit, int cpu)
 
 	BUILD_BUG_ON(STACK_INT_FRAME_SIZE % 16);
 
-	ptr = memblock_alloc_try_nid(THREAD_SIZE, THREAD_SIZE,
+	ptr = memblock_alloc_try_nid(THREAD_SIZE, THREAD_ALIGN,
 				     MEMBLOCK_LOW_LIMIT, limit,
 				     early_cpu_to_node(cpu));
 	if (!ptr)
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index 060a1acd7c6d..d38335129c06 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -346,7 +346,7 @@ SECTIONS
 #endif
 
 	/* The initial task and kernel stack */
-	INIT_TASK_DATA_SECTION(THREAD_SIZE)
+	INIT_TASK_DATA_SECTION(THREAD_ALIGN)
 
 	.data..page_aligned : AT(ADDR(.data..page_aligned) - LOAD_OFFSET) {
 		PAGE_ALIGNED_DATA(PAGE_SIZE)
-- 
2.13.3


WARNING: multiple messages have this Message-ID (diff)
From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	 npiggin@gmail.com, dja@axtens.net
Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v3 07/15] powerpc: align stack to 2 * THREAD_SIZE with VMAP_STACK
Date: Tue, 10 Sep 2019 09:16:26 +0000 (UTC)	[thread overview]
Message-ID: <4ddb131f8a1db7eb01b65dc057234c824e889dd3.1568106758.git.christophe.leroy@c-s.fr> (raw)
In-Reply-To: <cover.1568106758.git.christophe.leroy@c-s.fr>

In order to ease stack overflow detection, align
stack to 2 * THREAD_SIZE when using VMAP_STACK.
This allows overflow detection using a single bit check.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/include/asm/thread_info.h | 13 +++++++++++++
 arch/powerpc/kernel/setup_32.c         |  2 +-
 arch/powerpc/kernel/setup_64.c         |  2 +-
 arch/powerpc/kernel/vmlinux.lds.S      |  2 +-
 4 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h
index 488d5c4670ff..a2270749b282 100644
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -22,6 +22,19 @@
 
 #define THREAD_SIZE		(1 << THREAD_SHIFT)
 
+/*
+ * By aligning VMAP'd stacks to 2 * THREAD_SIZE, we can detect overflow by
+ * checking sp & (1 << THREAD_SHIFT), which we can do cheaply in the entry
+ * assembly.
+ */
+#ifdef CONFIG_VMAP_STACK
+#define THREAD_ALIGN_SHIFT	(THREAD_SHIFT + 1)
+#else
+#define THREAD_ALIGN_SHIFT	THREAD_SHIFT
+#endif
+
+#define THREAD_ALIGN		(1 << THREAD_ALIGN_SHIFT)
+
 #ifndef __ASSEMBLY__
 #include <linux/cache.h>
 #include <asm/processor.h>
diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index a7541edf0cdb..180e658c1a6b 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -137,7 +137,7 @@ arch_initcall(ppc_init);
 
 static void *__init alloc_stack(void)
 {
-	void *ptr = memblock_alloc(THREAD_SIZE, THREAD_SIZE);
+	void *ptr = memblock_alloc(THREAD_SIZE, THREAD_ALIGN);
 
 	if (!ptr)
 		panic("cannot allocate %d bytes for stack at %pS\n",
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 44b4c432a273..f630fe4d36a8 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -644,7 +644,7 @@ static void *__init alloc_stack(unsigned long limit, int cpu)
 
 	BUILD_BUG_ON(STACK_INT_FRAME_SIZE % 16);
 
-	ptr = memblock_alloc_try_nid(THREAD_SIZE, THREAD_SIZE,
+	ptr = memblock_alloc_try_nid(THREAD_SIZE, THREAD_ALIGN,
 				     MEMBLOCK_LOW_LIMIT, limit,
 				     early_cpu_to_node(cpu));
 	if (!ptr)
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index 060a1acd7c6d..d38335129c06 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -346,7 +346,7 @@ SECTIONS
 #endif
 
 	/* The initial task and kernel stack */
-	INIT_TASK_DATA_SECTION(THREAD_SIZE)
+	INIT_TASK_DATA_SECTION(THREAD_ALIGN)
 
 	.data..page_aligned : AT(ADDR(.data..page_aligned) - LOAD_OFFSET) {
 		PAGE_ALIGNED_DATA(PAGE_SIZE)
-- 
2.13.3


  parent reply	other threads:[~2019-09-10  9:17 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-10  9:16 [PATCH v3 00/15] Enable CONFIG_VMAP_STACK on PPC32 Christophe Leroy
2019-09-10  9:16 ` Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 01/15] powerpc/32: replace MTMSRD() by mtmsr Christophe Leroy
2019-09-10  9:16   ` Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 02/15] powerpc/32: Add EXCEPTION_PROLOG_0 in head_32.h Christophe Leroy
2019-09-10  9:16   ` Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 03/15] powerpc/32: save DEAR/DAR before calling handle_page_fault Christophe Leroy
2019-09-10  9:16   ` Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 04/15] powerpc/32: move MSR_PR test into EXCEPTION_PROLOG_0 Christophe Leroy
2019-09-10  9:16   ` Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 05/15] powerpc/32: add a macro to get and/or save DAR and DSISR on stack Christophe Leroy
2019-09-10  9:16   ` Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 06/15] powerpc/32: prepare for CONFIG_VMAP_STACK Christophe Leroy
2019-09-10  9:16   ` Christophe Leroy
2019-10-17  7:36   ` Andrew Donnellan
2019-10-17  7:36     ` Andrew Donnellan
2019-10-18  6:46     ` Christophe Leroy
2019-10-18  6:46       ` Christophe Leroy
2019-10-18  7:09       ` Andrew Donnellan
2019-10-18  7:09         ` Andrew Donnellan
2019-09-10  9:16 ` Christophe Leroy [this message]
2019-09-10  9:16   ` [PATCH v3 07/15] powerpc: align stack to 2 * THREAD_SIZE with VMAP_STACK Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 08/15] powerpc/32: Add early stack overflow detection with VMAP stack Christophe Leroy
2019-09-10  9:16   ` Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 09/15] powerpc/8xx: Use alternative scratch registers in DTLB miss handler Christophe Leroy
2019-09-10  9:16   ` Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 10/15] powerpc/8xx: drop exception entries for non-existing exceptions Christophe Leroy
2019-09-10  9:16   ` Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 11/15] powerpc/8xx: move DataStoreTLBMiss perf handler Christophe Leroy
2019-09-10  9:16   ` Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 12/15] powerpc/8xx: split breakpoint exception Christophe Leroy
2019-09-10  9:16   ` Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 13/15] powerpc/8xx: Enable CONFIG_VMAP_STACK Christophe Leroy
2019-09-10  9:16   ` Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 14/15] powerpc/32s: reorganise DSI handler Christophe Leroy
2019-09-10  9:16   ` Christophe Leroy
2019-09-10  9:16 ` [PATCH v3 15/15] powerpc/32s: Activate CONFIG_VMAP_STACK Christophe Leroy
2019-09-10  9:16   ` Christophe Leroy
2019-11-18 11:11   ` Michael Ellerman
2019-11-18 11:11     ` Michael Ellerman
2019-11-19  6:57     ` Michael Ellerman
2019-11-19  6:57       ` Michael Ellerman
2019-11-19 17:23     ` Christophe Leroy
2019-11-19 17:23       ` Christophe Leroy
2019-11-19  6:58   ` Michael Ellerman
2019-11-19  6:58     ` Michael Ellerman
2019-11-20  7:38     ` Christophe Leroy
2019-11-20  7:38       ` Christophe Leroy
2019-11-26  9:01     ` Christophe Leroy
2019-11-26  9:01       ` Christophe Leroy

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