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Subject[PATCH 27/43] x86: kmsan: add iomem support
From
Functions from lib/iomap.c and arch/x86/lib/iomem.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@google.com>

---
Link: https://linux-review.googlesource.com/id/I45527599f09090aca046dfe1a26df453adab100d
---
arch/x86/lib/iomem.c | 5 +++++
lib/iomap.c | 40 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 45 insertions(+)

diff --git a/arch/x86/lib/iomem.c b/arch/x86/lib/iomem.c
index df50451d94ef7..2307770f3f4c8 100644
--- a/arch/x86/lib/iomem.c
+++ b/arch/x86/lib/iomem.c
@@ -1,6 +1,7 @@
#include <linux/string.h>
#include <linux/module.h>
#include <linux/io.h>
+#include <linux/kmsan-checks.h>

#define movs(type,to,from) \
asm volatile("movs" type:"=&D" (to), "=&S" (from):"0" (to), "1" (from):"memory")
@@ -37,6 +38,8 @@ void memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
n-=2;
}
rep_movs(to, (const void *)from, n);
+ /* KMSAN must treat values read from devices as initialized. */
+ kmsan_unpoison_memory(to, n);
}
EXPORT_SYMBOL(memcpy_fromio);

@@ -45,6 +48,8 @@ void memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
if (unlikely(!n))
return;

+ /* Make sure uninitialized memory isn't copied to devices. */
+ kmsan_check_memory(from, n);
/* Align any unaligned destination IO */
if (unlikely(1 & (unsigned long)to)) {
movs("b", to, from);
diff --git a/lib/iomap.c b/lib/iomap.c
index fbaa3e8f19d6c..bdda1a42771b2 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 +71,31 @@ static void bad_io_access(unsigned long port, const char *access)
#define mmio_read64be(addr) swab64(readq(addr))
#endif

+__no_sanitize_memory
unsigned int ioread8(const void __iomem *addr)
{
IO_COND(addr, return inb(port), return readb(addr));
return 0xff;
}
+__no_sanitize_memory
unsigned int ioread16(const void __iomem *addr)
{
IO_COND(addr, return inw(port), return readw(addr));
return 0xffff;
}
+__no_sanitize_memory
unsigned int ioread16be(const void __iomem *addr)
{
IO_COND(addr, return pio_read16be(port), return mmio_read16be(addr));
return 0xffff;
}
+__no_sanitize_memory
unsigned int ioread32(const void __iomem *addr)
{
IO_COND(addr, return inl(port), return readl(addr));
return 0xffffffff;
}
+__no_sanitize_memory
unsigned int ioread32be(const void __iomem *addr)
{
IO_COND(addr, return pio_read32be(port), return mmio_read32be(addr));
@@ -142,18 +148,21 @@ static u64 pio_read64be_hi_lo(unsigned long port)
return lo | (hi << 32);
}

+__no_sanitize_memory
u64 ioread64_lo_hi(const void __iomem *addr)
{
IO_COND(addr, return pio_read64_lo_hi(port), return readq(addr));
return 0xffffffffffffffffULL;
}

+__no_sanitize_memory
u64 ioread64_hi_lo(const void __iomem *addr)
{
IO_COND(addr, return pio_read64_hi_lo(port), return readq(addr));
return 0xffffffffffffffffULL;
}

+__no_sanitize_memory
u64 ioread64be_lo_hi(const void __iomem *addr)
{
IO_COND(addr, return pio_read64be_lo_hi(port),
@@ -161,6 +170,7 @@ u64 ioread64be_lo_hi(const void __iomem *addr)
return 0xffffffffffffffffULL;
}

+__no_sanitize_memory
u64 ioread64be_hi_lo(const void __iomem *addr)
{
IO_COND(addr, return pio_read64be_hi_lo(port),
@@ -188,22 +198,32 @@ 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 +259,32 @@ 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 +356,20 @@ 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 +377,20 @@ 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);
--
2.34.1.173.g76aa8bc2d0-goog
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