kmsan: add iomap support

Functions from lib/iomap.c interact with hardware, so KMSAN must ensure
that:
 - every read function returns an initialized value
 - every write function checks values before sending them to hardware.

Link: https://lkml.kernel.org/r/20220915150417.722975-20-glider@google.comSigned-off-by: Alexander Potapenko <glider@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Marco Elver <elver@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

lib/iomap.c

@@ -6,6 +6,7 @@
  */
 #include <linux/pci.h>
 #include <linux/io.h>
+#include <linux/kmsan-checks.h>
 
 #include <linux/export.h>
 
@@ -70,26 +71,35 @@ static void bad_io_access(unsigned long port, const char *access)
 #define mmio_read64be(addr) swab64(readq(addr))
 #endif
 
+/*
+ * Here and below, we apply __no_kmsan_checks to functions reading data from
+ * hardware, to ensure that KMSAN marks their return values as initialized.
+ */
+__no_kmsan_checks
 unsigned int ioread8(const void __iomem *addr)
 {
 	IO_COND(addr, return inb(port), return readb(addr));
 	return 0xff;
 }
+__no_kmsan_checks
 unsigned int ioread16(const void __iomem *addr)
 {
 	IO_COND(addr, return inw(port), return readw(addr));
 	return 0xffff;
 }
+__no_kmsan_checks
 unsigned int ioread16be(const void __iomem *addr)
 {
 	IO_COND(addr, return pio_read16be(port), return mmio_read16be(addr));
 	return 0xffff;
 }
+__no_kmsan_checks
 unsigned int ioread32(const void __iomem *addr)
 {
 	IO_COND(addr, return inl(port), return readl(addr));
 	return 0xffffffff;
 }
+__no_kmsan_checks
 unsigned int ioread32be(const void __iomem *addr)
 {
 	IO_COND(addr, return pio_read32be(port), return mmio_read32be(addr));
@@ -142,18 +152,21 @@ static u64 pio_read64be_hi_lo(unsigned long port)
 	return lo | (hi << 32);
 }
 
+__no_kmsan_checks
 u64 ioread64_lo_hi(const void __iomem *addr)
 {
 	IO_COND(addr, return pio_read64_lo_hi(port), return readq(addr));
 	return 0xffffffffffffffffULL;
 }
 
+__no_kmsan_checks
 u64 ioread64_hi_lo(const void __iomem *addr)
 {
 	IO_COND(addr, return pio_read64_hi_lo(port), return readq(addr));
 	return 0xffffffffffffffffULL;
 }
 
+__no_kmsan_checks
 u64 ioread64be_lo_hi(const void __iomem *addr)
 {
 	IO_COND(addr, return pio_read64be_lo_hi(port),
@@ -161,6 +174,7 @@ u64 ioread64be_lo_hi(const void __iomem *addr)
 	return 0xffffffffffffffffULL;
 }
 
+__no_kmsan_checks
 u64 ioread64be_hi_lo(const void __iomem *addr)
 {
 	IO_COND(addr, return pio_read64be_hi_lo(port),
@@ -188,22 +202,32 @@ EXPORT_SYMBOL(ioread64be_hi_lo);
 
 void iowrite8(u8 val, void __iomem *addr)
 {
+	/* Make sure uninitialized memory isn't copied to devices. */
+	kmsan_check_memory(&val, sizeof(val));
 	IO_COND(addr, outb(val,port), writeb(val, addr));
 }
 void iowrite16(u16 val, void __iomem *addr)
 {
+	/* Make sure uninitialized memory isn't copied to devices. */
+	kmsan_check_memory(&val, sizeof(val));
 	IO_COND(addr, outw(val,port), writew(val, addr));
 }
 void iowrite16be(u16 val, void __iomem *addr)
 {
+	/* Make sure uninitialized memory isn't copied to devices. */
+	kmsan_check_memory(&val, sizeof(val));
 	IO_COND(addr, pio_write16be(val,port), mmio_write16be(val, addr));
 }
 void iowrite32(u32 val, void __iomem *addr)
 {
+	/* Make sure uninitialized memory isn't copied to devices. */
+	kmsan_check_memory(&val, sizeof(val));
 	IO_COND(addr, outl(val,port), writel(val, addr));
 }
 void iowrite32be(u32 val, void __iomem *addr)
 {
+	/* Make sure uninitialized memory isn't copied to devices. */
+	kmsan_check_memory(&val, sizeof(val));
 	IO_COND(addr, pio_write32be(val,port), mmio_write32be(val, addr));
 }
 EXPORT_SYMBOL(iowrite8);
@@ -239,24 +263,32 @@ static void pio_write64be_hi_lo(u64 val, unsigned long port)
 
 void iowrite64_lo_hi(u64 val, void __iomem *addr)
 {
+	/* Make sure uninitialized memory isn't copied to devices. */
+	kmsan_check_memory(&val, sizeof(val));
 	IO_COND(addr, pio_write64_lo_hi(val, port),
 		writeq(val, addr));
 }
 
 void iowrite64_hi_lo(u64 val, void __iomem *addr)
 {
+	/* Make sure uninitialized memory isn't copied to devices. */
+	kmsan_check_memory(&val, sizeof(val));
 	IO_COND(addr, pio_write64_hi_lo(val, port),
 		writeq(val, addr));
 }
 
 void iowrite64be_lo_hi(u64 val, void __iomem *addr)
 {
+	/* Make sure uninitialized memory isn't copied to devices. */
+	kmsan_check_memory(&val, sizeof(val));
 	IO_COND(addr, pio_write64be_lo_hi(val, port),
 		mmio_write64be(val, addr));
 }
 
 void iowrite64be_hi_lo(u64 val, void __iomem *addr)
 {
+	/* Make sure uninitialized memory isn't copied to devices. */
+	kmsan_check_memory(&val, sizeof(val));
 	IO_COND(addr, pio_write64be_hi_lo(val, port),
 		mmio_write64be(val, addr));
 }
@@ -328,14 +360,20 @@ static inline void mmio_outsl(void __iomem *addr, const u32 *src, int count)
 void ioread8_rep(const void __iomem *addr, void *dst, unsigned long count)
 {
 	IO_COND(addr, insb(port,dst,count), mmio_insb(addr, dst, count));
+	/* KMSAN must treat values read from devices as initialized. */
+	kmsan_unpoison_memory(dst, count);
 }
 void ioread16_rep(const void __iomem *addr, void *dst, unsigned long count)
 {
 	IO_COND(addr, insw(port,dst,count), mmio_insw(addr, dst, count));
+	/* KMSAN must treat values read from devices as initialized. */
+	kmsan_unpoison_memory(dst, count * 2);
 }
 void ioread32_rep(const void __iomem *addr, void *dst, unsigned long count)
 {
 	IO_COND(addr, insl(port,dst,count), mmio_insl(addr, dst, count));
+	/* KMSAN must treat values read from devices as initialized. */
+	kmsan_unpoison_memory(dst, count * 4);
 }
 EXPORT_SYMBOL(ioread8_rep);
 EXPORT_SYMBOL(ioread16_rep);
@@ -343,14 +381,20 @@ EXPORT_SYMBOL(ioread32_rep);
 
 void iowrite8_rep(void __iomem *addr, const void *src, unsigned long count)
 {
+	/* Make sure uninitialized memory isn't copied to devices. */
+	kmsan_check_memory(src, count);
 	IO_COND(addr, outsb(port, src, count), mmio_outsb(addr, src, count));
 }
 void iowrite16_rep(void __iomem *addr, const void *src, unsigned long count)
 {
+	/* Make sure uninitialized memory isn't copied to devices. */
+	kmsan_check_memory(src, count * 2);
 	IO_COND(addr, outsw(port, src, count), mmio_outsw(addr, src, count));
 }
 void iowrite32_rep(void __iomem *addr, const void *src, unsigned long count)
 {
+	/* Make sure uninitialized memory isn't copied to devices. */
+	kmsan_check_memory(src, count * 4);
 	IO_COND(addr, outsl(port, src,count), mmio_outsl(addr, src, count));
 }
 EXPORT_SYMBOL(iowrite8_rep);