diff mbox series

[v2,27/33] s390/mm: Define KMSAN metadata for vmalloc and modules

Message ID 20231121220155.1217090-28-iii@linux.ibm.com
State New
Headers
Series kmsan: Enable on s390 |

Commit Message

Ilya Leoshkevich Nov. 21, 2023, 10:01 p.m. UTC 
  The pages for the KMSAN metadata associated with most kernel mappings
are taken from memblock by the common code. However, vmalloc and module
metadata needs to be defined by the architectures.

Be a little bit more careful than x86: allocate exactly MODULES_LEN
for the module shadow and origins, and then take 2/3 of vmalloc for
the vmalloc shadow and origins. This ensures that users passing small
vmalloc= values on the command line do not cause module metadata
collisions.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 arch/s390/boot/startup.c        |  8 ++++++++
 arch/s390/include/asm/pgtable.h | 10 ++++++++++
 2 files changed, 18 insertions(+)

Comments

Alexander Potapenko Dec. 11, 2023, 10:13 a.m. UTC | #1 
On Tue, Nov 21, 2023 at 11:07 PM Ilya Leoshkevich <iii@linux.ibm.com> wrote:
>
> The pages for the KMSAN metadata associated with most kernel mappings
> are taken from memblock by the common code. However, vmalloc and module
> metadata needs to be defined by the architectures.
>
> Be a little bit more careful than x86: allocate exactly MODULES_LEN
> for the module shadow and origins, and then take 2/3 of vmalloc for
> the vmalloc shadow and origins. This ensures that users passing small
> vmalloc= values on the command line do not cause module metadata
> collisions.
>
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Alexander Potapenko <glider@google.com>

(hope some s390 maintainer acks this as well)
diff mbox series

Patch

diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c
index 8104e0e3d188..e37e7ffda430 100644
--- a/arch/s390/boot/startup.c
+++ b/arch/s390/boot/startup.c
@@ -253,9 +253,17 @@  static unsigned long setup_kernel_memory_layout(void)
 	MODULES_END = round_down(__abs_lowcore, _SEGMENT_SIZE);
 	MODULES_VADDR = MODULES_END - MODULES_LEN;
 	VMALLOC_END = MODULES_VADDR;
+#ifdef CONFIG_KMSAN
+	VMALLOC_END -= MODULES_LEN * 2;
+#endif
 
 	/* allow vmalloc area to occupy up to about 1/2 of the rest virtual space left */
 	vmalloc_size = min(vmalloc_size, round_down(VMALLOC_END / 2, _REGION3_SIZE));
+#ifdef CONFIG_KMSAN
+	/* take 2/3 of vmalloc area for KMSAN shadow and origins */
+	vmalloc_size = round_down(vmalloc_size / 3, _REGION3_SIZE);
+	VMALLOC_END -= vmalloc_size * 2;
+#endif
 	VMALLOC_START = VMALLOC_END - vmalloc_size;
 
 	/* split remaining virtual space between 1:1 mapping & vmemmap array */
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 601e87fa8a9a..d764abeb9e6d 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -107,6 +107,16 @@  static inline int is_module_addr(void *addr)
 	return 1;
 }
 
+#ifdef CONFIG_KMSAN
+#define KMSAN_VMALLOC_SIZE (VMALLOC_END - VMALLOC_START)
+#define KMSAN_VMALLOC_SHADOW_START VMALLOC_END
+#define KMSAN_VMALLOC_ORIGIN_START (KMSAN_VMALLOC_SHADOW_START + \
+				    KMSAN_VMALLOC_SIZE)
+#define KMSAN_MODULES_SHADOW_START (KMSAN_VMALLOC_ORIGIN_START + \
+				    KMSAN_VMALLOC_SIZE)
+#define KMSAN_MODULES_ORIGIN_START (KMSAN_MODULES_SHADOW_START + MODULES_LEN)
+#endif
+
 /*
  * A 64 bit pagetable entry of S390 has following format:
  * |			 PFRA			      |0IPC|  OS  |