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Message-ID: <20220905122452.2258262-21-glider@google.com>
Date:   Mon,  5 Sep 2022 14:24:28 +0200
From:   Alexander Potapenko <glider@...gle.com>
To:     glider@...gle.com
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        Alexei Starovoitov <ast@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
        Christoph Hellwig <hch@....de>,
        Christoph Lameter <cl@...ux.com>,
        David Rientjes <rientjes@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Ilya Leoshkevich <iii@...ux.ibm.com>,
        Ingo Molnar <mingo@...hat.com>, Jens Axboe <axboe@...nel.dk>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Kees Cook <keescook@...omium.org>,
        Marco Elver <elver@...gle.com>,
        Mark Rutland <mark.rutland@....com>,
        Matthew Wilcox <willy@...radead.org>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Pekka Enberg <penberg@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Vegard Nossum <vegard.nossum@...cle.com>,
        Vlastimil Babka <vbabka@...e.cz>, kasan-dev@...glegroups.com,
        linux-mm@...ck.org, linux-arch@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v6 20/44] 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.

Signed-off-by: Alexander Potapenko <glider@...gle.com>

---

v4:
  -- switch from __no_sanitize_memory (which now means "no KMSAN
     instrumentation") to __no_kmsan_checks (i.e. "unpoison everything")

Link: https://linux-review.googlesource.com/id/I45527599f09090aca046dfe1a26df453adab100d
---
 lib/iomap.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/lib/iomap.c b/lib/iomap.c
index fbaa3e8f19d6c..4f8b31baa5752 100644
--- a/lib/iomap.c
+++ b/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);
-- 
2.37.2.789.g6183377224-goog

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