2013-07-20 16:37:49

by Ren Qiaowei

Subject: [PATCH v5] x86, tboot: iomem fixes

Current code doesn't use specific interface to access I/O space.
So some potential bugs can be caused. We can fix this by using
specific API.

Signed-off-by: Qiaowei Ren <[email protected]>
---
arch/x86/kernel/tboot.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c
index 3ff42d2..4e149c7 100644
--- a/arch/x86/kernel/tboot.c
+++ b/arch/x86/kernel/tboot.c
@@ -468,7 +468,8 @@ struct sinit_mle_data {

struct acpi_table_header *tboot_get_dmar_table(struct acpi_table_header *dmar_tbl)
{
- void *heap_base, *heap_ptr, *config;
+ void __iomem *heap_base, *heap_ptr, *config;
+ u32 dmar_tbl_off;

if (!tboot_enabled())
return dmar_tbl;
@@ -485,25 +486,26 @@ struct acpi_table_header *tboot_get_dmar_table(struct acpi_table_header *dmar_tb
return NULL;

/* now map TXT heap */
- heap_base = ioremap(*(u64 *)(config + TXTCR_HEAP_BASE),
- *(u64 *)(config + TXTCR_HEAP_SIZE));
+ heap_base = ioremap(readl(config + TXTCR_HEAP_BASE),
+ readl(config + TXTCR_HEAP_SIZE));
iounmap(config);
if (!heap_base)
return NULL;

/* walk heap to SinitMleData */
/* skip BiosData */
- heap_ptr = heap_base + *(u64 *)heap_base;
+ heap_ptr = heap_base + readq(heap_base);
/* skip OsMleData */
- heap_ptr += *(u64 *)heap_ptr;
+ heap_ptr += readq(heap_ptr);
/* skip OsSinitData */
- heap_ptr += *(u64 *)heap_ptr;
+ heap_ptr += readq(heap_ptr);
/* now points to SinitMleDataSize; set to SinitMleData */
heap_ptr += sizeof(u64);
/* get addr of DMAR table */
+ dmar_tbl_off = readl(heap_ptr +
+ offsetof(struct sinit_mle_data, vtd_dmars_off));
dmar_tbl = (struct acpi_table_header *)(heap_ptr +
- ((struct sinit_mle_data *)heap_ptr)->vtd_dmars_off -
- sizeof(u64));
+ dmar_tbl_off - sizeof(u64));

/* don't unmap heap because dmar.c needs access to this */

--
1.7.9.5

2013-07-22 08:50:44

by Ingo Molnar

Subject: Re: [PATCH v5] x86, tboot: iomem fixes

* Qiaowei Ren <[email protected]> wrote:

> Current code doesn't use specific interface to access I/O space.
> So some potential bugs can be caused. We can fix this by using
> specific API.
>
> Signed-off-by: Qiaowei Ren <[email protected]>
> ---
> arch/x86/kernel/tboot.c | 18 ++++++++++--------
> 1 file changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c
> index 3ff42d2..4e149c7 100644
> --- a/arch/x86/kernel/tboot.c
> +++ b/arch/x86/kernel/tboot.c
> @@ -468,7 +468,8 @@ struct sinit_mle_data {
>
> struct acpi_table_header *tboot_get_dmar_table(struct acpi_table_header *dmar_tbl)
> {
> - void *heap_base, *heap_ptr, *config;
> + void __iomem *heap_base, *heap_ptr, *config;
> + u32 dmar_tbl_off;
>
> if (!tboot_enabled())
> return dmar_tbl;
> @@ -485,25 +486,26 @@ struct acpi_table_header *tboot_get_dmar_table(struct acpi_table_header *dmar_tb
> return NULL;
>
> /* now map TXT heap */
> - heap_base = ioremap(*(u64 *)(config + TXTCR_HEAP_BASE),
> - *(u64 *)(config + TXTCR_HEAP_SIZE));
> + heap_base = ioremap(readl(config + TXTCR_HEAP_BASE),
> + readl(config + TXTCR_HEAP_SIZE));
> iounmap(config);
> if (!heap_base)
> return NULL;
>
> /* walk heap to SinitMleData */
> /* skip BiosData */
> - heap_ptr = heap_base + *(u64 *)heap_base;
> + heap_ptr = heap_base + readq(heap_base);
> /* skip OsMleData */
> - heap_ptr += *(u64 *)heap_ptr;
> + heap_ptr += readq(heap_ptr);

tboot.c is build on 32-bit kernel as well, but readq() is only available
on 64-bit systems.

Thanks,

Ingo

2013-08-06 22:27:36

by H. Peter Anvin

Subject: Re: [PATCH v5] x86, tboot: iomem fixes

On 07/20/2013 09:26 AM, Qiaowei Ren wrote:
>
> /* now map TXT heap */
> - heap_base = ioremap(*(u64 *)(config + TXTCR_HEAP_BASE),
> - *(u64 *)(config + TXTCR_HEAP_SIZE));
> + heap_base = ioremap(readl(config + TXTCR_HEAP_BASE),
> + readl(config + TXTCR_HEAP_SIZE));

You are changing u64 references to readl()... this means you are doing
only 32-bit reads.

> iounmap(config);
> if (!heap_base)
> return NULL;
>
> /* walk heap to SinitMleData */
> /* skip BiosData */
> - heap_ptr = heap_base + *(u64 *)heap_base;
> + heap_ptr = heap_base + readq(heap_base);
> /* skip OsMleData */
> - heap_ptr += *(u64 *)heap_ptr;
> + heap_ptr += readq(heap_ptr);
> /* skip OsSinitData */
> - heap_ptr += *(u64 *)heap_ptr;
> + heap_ptr += readq(heap_ptr);

As I believe Ingo already commented on, readq() only exists on 64 bits.

You can #include <asm-generic/io-64-nonatomic-lo-hi.h> to remedy that.

> /* now points to SinitMleDataSize; set to SinitMleData */
> heap_ptr += sizeof(u64);
> /* get addr of DMAR table */
> + dmar_tbl_off = readl(heap_ptr +
> + offsetof(struct sinit_mle_data, vtd_dmars_off));
> dmar_tbl = (struct acpi_table_header *)(heap_ptr +
> - ((struct sinit_mle_data *)heap_ptr)->vtd_dmars_off -
> - sizeof(u64));
> + dmar_tbl_off - sizeof(u64));
>
> /* don't unmap heap because dmar.c needs access to this */
>

If you are using accessors here, what about dmar_tbl itself?

-hpa