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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>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
This commit is contained in:
Jian J Wang 2018-02-06 10:08:25 +08:00 committed by Ruiyu Ni
parent 7823611cda
commit 890d9ee554
1 changed files with 17 additions and 4 deletions
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21
UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c
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@ -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) {