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[v4,29/35] s390/mm: Define KMSAN metadata for vmalloc and modules

Message ID 20240613153924.961511-30-iii@linux.ibm.com (mailing list archive)
State Superseded
Headers show
Series kmsan: Enable on s390 | expand

Commit Message

Ilya Leoshkevich June 13, 2024, 3:34 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.

Reviewed-by: Alexander Potapenko <glider@google.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 arch/s390/boot/startup.c        | 7 +++++++
 arch/s390/include/asm/pgtable.h | 8 ++++++++
 2 files changed, 15 insertions(+)
diff mbox series

Patch

diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c
index 182aac6a0f77..93775142322d 100644
--- a/arch/s390/boot/startup.c
+++ b/arch/s390/boot/startup.c
@@ -301,11 +301,18 @@  static unsigned long setup_kernel_memory_layout(unsigned long kernel_size)
 	MODULES_END = round_down(kernel_start, _SEGMENT_SIZE);
 	MODULES_VADDR = MODULES_END - MODULES_LEN;
 	VMALLOC_END = MODULES_VADDR;
+	if (IS_ENABLED(CONFIG_KMSAN))
+		VMALLOC_END -= MODULES_LEN * 2;
 
 	/* allow vmalloc area to occupy up to about 1/2 of the rest virtual space left */
 	vsize = (VMALLOC_END - FIXMAP_SIZE) / 2;
 	vsize = round_down(vsize, _SEGMENT_SIZE);
 	vmalloc_size = min(vmalloc_size, vsize);
+	if (IS_ENABLED(CONFIG_KMSAN)) {
+		/* take 2/3 of vmalloc area for KMSAN shadow and origins */
+		vmalloc_size = round_down(vmalloc_size / 3, _SEGMENT_SIZE);
+		VMALLOC_END -= vmalloc_size * 2;
+	}
 	VMALLOC_START = VMALLOC_END - vmalloc_size;
 
 	__memcpy_real_area = round_down(VMALLOC_START - MEMCPY_REAL_SIZE, PAGE_SIZE);
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 70b6ee557eb2..2f44c23efec0 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -107,6 +107,14 @@  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
+
 #ifdef CONFIG_RANDOMIZE_BASE
 #define KASLR_LEN	(1UL << 31)
 #else