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[edk2] [PATCH v2] UefiCpuPkg/PiSmmCpuDxeSmm: fix infinite loop issue in SMM profile

Jian J Wang posted 1 patch 6 years, 10 months ago
Failed in applying to current master (apply log)
UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c | 21 +++++++++++++++++----
1 file changed, 17 insertions(+), 4 deletions(-)
[edk2] [PATCH v2] UefiCpuPkg/PiSmmCpuDxeSmm: fix infinite loop issue in SMM profile
Posted by Jian J Wang 6 years, 10 months ago 
> v2:
>   Reduce the number of page to update/restore from 3 to 2 because DF
>   has no effect in this issue.

The infinite loop is caused by the memory instruction, such as
"rep mov", operating on memory block crossing boundary of NON-PRESENT
pages. Because the address triggering page fault set in CR2 will be in
the first page, SmmProfilePFHandler() will only change the first page
into PRESENT. The page following will be still in NON-PRESENT status.

Since SmmProfilePFHandler() will setup single-step trap for the
instruction causing #PF, when the handler returns back to the
instruction and re-execute it, both #DB and #PF will be triggered
because the instruction wants to access both first and second page
but only first page is PRESENT.

Normally #DB exception will be handled first and its handler will
change first page back to NON-PRESENT status. Then #PF is handled
and its handler will change first page to PRESENT status again and
setup another single-step for the instruction triggering #PF. Then
the whole system falls into an infinite loop and the memory operation
will never move on.

This patch fix above situation by always changing 2 pages to PRESENT
status instead of just 1 page. Those 2 pages include the page causing
#PF and the page after it.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
---
 UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c
index 9588eaf029..c90167f160 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c
@@ -1302,6 +1302,8 @@ SmmProfilePFHandler (
 {
   UINT64                *PageTable;
   UINT64                PFAddress;
+  UINT64                RestoreAddress;
+  UINTN                 RestorePageNumber;
   UINTN                 CpuIndex;
   UINTN                 Index;
   UINT64                InstructionAddress;
@@ -1331,10 +1333,21 @@ SmmProfilePFHandler (
   PFAddress         = AsmReadCr2 ();
   CpuIndex          = GetCpuIndex ();
 
-  if (PFAddress <= 0xFFFFFFFF) {
-    RestorePageTableBelow4G (PageTable, PFAddress, CpuIndex, ErrorCode);
-  } else {
-    RestorePageTableAbove4G (PageTable, PFAddress, CpuIndex, ErrorCode, &IsValidPFAddress);
+  //
+  // Memory operation cross pages, like "rep mov" instruction, will cause
+  // infinite loop between this and Debug Trap handler. We have to make sure
+  // that current page and the page followed are both in PRESENT state.
+  //
+  RestorePageNumber = 2;
+  RestoreAddress = PFAddress;
+  while (RestorePageNumber > 0) {
+    if (RestoreAddress <= 0xFFFFFFFF) {
+      RestorePageTableBelow4G (PageTable, RestoreAddress, CpuIndex, ErrorCode);
+    } else {
+      RestorePageTableAbove4G (PageTable, RestoreAddress, CpuIndex, ErrorCode, &IsValidPFAddress);
+    }
+    RestoreAddress += EFI_PAGE_SIZE;
+    RestorePageNumber--;
   }
 
   if (!IsValidPFAddress) {
-- 
2.14.1.windows.1

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Re: [edk2] [PATCH v2] UefiCpuPkg/PiSmmCpuDxeSmm: fix infinite loop issue in SMM profile
Posted by Yao, Jiewen 6 years, 10 months ago 
Reviewed-by: Jiewen.yao@intel.com

> -----Original Message-----
> From: Wang, Jian J
> Sent: Tuesday, February 6, 2018 4:40 PM
> To: edk2-devel@lists.01.org
> Cc: Dong, Eric <eric.dong@intel.com>; Laszlo Ersek <lersek@redhat.com>; Ni,
> Ruiyu <ruiyu.ni@intel.com>; Yao, Jiewen <jiewen.yao@intel.com>
> Subject: [PATCH v2] UefiCpuPkg/PiSmmCpuDxeSmm: fix infinite loop issue in
> SMM profile
> 
> > v2:
> >   Reduce the number of page to update/restore from 3 to 2 because DF
> >   has no effect in this issue.
> 
> The infinite loop is caused by the memory instruction, such as
> "rep mov", operating on memory block crossing boundary of NON-PRESENT
> pages. Because the address triggering page fault set in CR2 will be in
> the first page, SmmProfilePFHandler() will only change the first page
> into PRESENT. The page following will be still in NON-PRESENT status.
> 
> Since SmmProfilePFHandler() will setup single-step trap for the
> instruction causing #PF, when the handler returns back to the
> instruction and re-execute it, both #DB and #PF will be triggered
> because the instruction wants to access both first and second page
> but only first page is PRESENT.
> 
> Normally #DB exception will be handled first and its handler will
> change first page back to NON-PRESENT status. Then #PF is handled
> and its handler will change first page to PRESENT status again and
> setup another single-step for the instruction triggering #PF. Then
> the whole system falls into an infinite loop and the memory operation
> will never move on.
> 
> This patch fix above situation by always changing 2 pages to PRESENT
> status instead of just 1 page. Those 2 pages include the page causing
> #PF and the page after it.
> 
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Ruiyu Ni <ruiyu.ni@intel.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
> ---
>  UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c | 21 +++++++++++++++++----
>  1 file changed, 17 insertions(+), 4 deletions(-)
> 
> diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c
> b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c
> index 9588eaf029..c90167f160 100644
> --- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c
> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c
> @@ -1302,6 +1302,8 @@ SmmProfilePFHandler (
>  {
>    UINT64                *PageTable;
>    UINT64                PFAddress;
> +  UINT64                RestoreAddress;
> +  UINTN                 RestorePageNumber;
>    UINTN                 CpuIndex;
>    UINTN                 Index;
>    UINT64                InstructionAddress;
> @@ -1331,10 +1333,21 @@ SmmProfilePFHandler (
>    PFAddress         = AsmReadCr2 ();
>    CpuIndex          = GetCpuIndex ();
> 
> -  if (PFAddress <= 0xFFFFFFFF) {
> -    RestorePageTableBelow4G (PageTable, PFAddress, CpuIndex, ErrorCode);
> -  } else {
> -    RestorePageTableAbove4G (PageTable, PFAddress, CpuIndex, ErrorCode,
> &IsValidPFAddress);
> +  //
> +  // Memory operation cross pages, like "rep mov" instruction, will cause
> +  // infinite loop between this and Debug Trap handler. We have to make sure
> +  // that current page and the page followed are both in PRESENT state.
> +  //
> +  RestorePageNumber = 2;
> +  RestoreAddress = PFAddress;
> +  while (RestorePageNumber > 0) {
> +    if (RestoreAddress <= 0xFFFFFFFF) {
> +      RestorePageTableBelow4G (PageTable, RestoreAddress, CpuIndex,
> ErrorCode);
> +    } else {
> +      RestorePageTableAbove4G (PageTable, RestoreAddress, CpuIndex,
> ErrorCode, &IsValidPFAddress);
> +    }
> +    RestoreAddress += EFI_PAGE_SIZE;
> +    RestorePageNumber--;
>    }
> 
>    if (!IsValidPFAddress) {
> --
> 2.14.1.windows.1

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