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>
Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org,
linux-kernel@vger.kernel.org
Subject: [PATCH v4 07/16] powerpc: align stack to 2 * THREAD_SIZE with VMAP_STACK
Date: Tue, 26 Nov 2019 12:36:10 +0000 (UTC) [thread overview]
Message-ID: <f28c9b5daf833e3b88f9c1245494b8aa73651a98.1574771540.git.christophe.leroy@c-s.fr> (raw)
In-Reply-To: <cover.1574771539.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 dcffe927f5b9..f014c4f7a337 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -140,7 +140,7 @@ 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 6104917a282d..e05e6dd67ae6 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -633,7 +633,7 @@ 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
next prev parent reply other threads:[~2019-11-26 13:00 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-26 12:36 [PATCH v4 00/16] Enable CONFIG_VMAP_STACK on PPC32 Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 01/16] powerpc/32: replace MTMSRD() by mtmsr Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 02/16] powerpc/32: Add EXCEPTION_PROLOG_0 in head_32.h Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 03/16] powerpc/32: save DEAR/DAR before calling handle_page_fault Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 04/16] powerpc/32: move MSR_PR test into EXCEPTION_PROLOG_0 Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 05/16] powerpc/32: add a macro to get and/or save DAR and DSISR on stack Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 06/16] powerpc/32: prepare for CONFIG_VMAP_STACK Christophe Leroy
2019-11-26 12:36 ` Christophe Leroy [this message]
2019-11-26 12:36 ` [PATCH v4 08/16] powerpc/32: Add early stack overflow detection with VMAP stack Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 09/16] powerpc/8xx: Use alternative scratch registers in DTLB miss handler Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 10/16] powerpc/8xx: drop exception entries for non-existing exceptions Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 11/16] powerpc/8xx: move DataStoreTLBMiss perf handler Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 12/16] powerpc/8xx: split breakpoint exception Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 13/16] powerpc/8xx: Enable CONFIG_VMAP_STACK Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 14/16] powerpc/32s: reorganise DSI handler Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 15/16] powerpc/32s: avoid crossing page boundary while changing SRR0/1 Christophe Leroy
2019-11-26 12:36 ` [PATCH v4 16/16] powerpc/32s: Activate CONFIG_VMAP_STACK Christophe Leroy
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