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ArmPkg/CpuDxe ARM: honour RO/XP attributes in SetMemoryAttributes() 

Enable the use of strict memory permissions on ARM by processing the
EFI_MEMORY_RO and EFI_MEMORY_XP rather than ignoring them. As before,
calls to CpuArchProtocol::SetMemoryAttributes that only set RO/XP
bits will preserve the cacheability attributes. Permissions attributes
are not preserved when setting the memory type only: the way the memory
permission attributes are defined does not allows for that, and so this
situation does not deviate from other architectures.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
This commit is contained in:
Ard Biesheuvel 2017-03-02 10:36:15 +00:00
parent 22c7a5b70e
commit 08b504d9d8
1 changed files with 86 additions and 92 deletions
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116
ArmPkg/Drivers/CpuDxe/Arm/Mmu.c
View File

@ -19,6 +19,13 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
#include <Library/MemoryAllocationLib.h>
#include "CpuDxe.h"
#define CACHE_ATTRIBUTE_MASK (EFI_MEMORY_UC | \
EFI_MEMORY_WC | \
EFI_MEMORY_WT | \
EFI_MEMORY_WB | \
EFI_MEMORY_UCE | \
EFI_MEMORY_WP)
// First Level Descriptors
typedef UINT32 ARM_FIRST_LEVEL_DESCRIPTOR;
@ -374,52 +381,50 @@ UpdatePageEntries (
// EntryMask: bitmask of values to change (1 = change this value, 0 = leave alone)
// EntryValue: values at bit positions specified by EntryMask
EntryMask = TT_DESCRIPTOR_PAGE_TYPE_MASK;
EntryMask = TT_DESCRIPTOR_PAGE_TYPE_MASK | TT_DESCRIPTOR_PAGE_AP_MASK;
if ((Attributes & EFI_MEMORY_XP) != 0) {
EntryValue = TT_DESCRIPTOR_PAGE_TYPE_PAGE_XN;
} else {
EntryValue = TT_DESCRIPTOR_PAGE_TYPE_PAGE;
// Although the PI spec is unclear on this the GCD guarantees that only
// one Attribute bit is set at a time, so we can safely use a switch statement
switch (Attributes) {
case EFI_MEMORY_UC:
}
// Although the PI spec is unclear on this, the GCD guarantees that only
// one Attribute bit is set at a time, so the order of the conditionals below
// is irrelevant. If no memory attribute is specified, we preserve whatever
// memory type is set in the page tables, and update the permission attributes
// only.
if (Attributes & EFI_MEMORY_UC) {
// modify cacheability attributes
EntryMask |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_MASK;
// map to strongly ordered
EntryValue |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_STRONGLY_ORDERED; // TEX[2:0] = 0, C=0, B=0
break;
case EFI_MEMORY_WC:
} else if (Attributes & EFI_MEMORY_WC) {
// modify cacheability attributes
EntryMask |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_MASK;
// map to normal non-cachable
EntryValue |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_NON_CACHEABLE; // TEX [2:0]= 001 = 0x2, B=0, C=0
break;
case EFI_MEMORY_WT:
} else if (Attributes & EFI_MEMORY_WT) {
// modify cacheability attributes
EntryMask |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_MASK;
// write through with no-allocate
EntryValue |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_WRITE_THROUGH_NO_ALLOC; // TEX [2:0] = 0, C=1, B=0
break;
case EFI_MEMORY_WB:
} else if (Attributes & EFI_MEMORY_WB) {
// modify cacheability attributes
EntryMask |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_MASK;
// write back (with allocate)
EntryValue |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_WRITE_BACK_ALLOC; // TEX [2:0] = 001, C=1, B=1
break;
case EFI_MEMORY_WP:
case EFI_MEMORY_XP:
case EFI_MEMORY_UCE:
// cannot be implemented UEFI definition unclear for ARM
// Cause a page fault if these ranges are accessed.
EntryValue = TT_DESCRIPTOR_PAGE_TYPE_FAULT;
DEBUG ((EFI_D_PAGE, "SetMemoryAttributes(): setting page %lx with unsupported attribute %x will page fault on access\n", BaseAddress, Attributes));
break;
default:
} else if (Attributes & CACHE_ATTRIBUTE_MASK) {
// catch unsupported memory type attributes
ASSERT (FALSE);
return EFI_UNSUPPORTED;
}
if ((Attributes & EFI_MEMORY_RO) != 0) {
EntryValue |= TT_DESCRIPTOR_PAGE_AP_RO_RO;
} else {
EntryValue |= TT_DESCRIPTOR_PAGE_AP_RW_RW;
}
// Obtain page table base
FirstLevelTable = (ARM_FIRST_LEVEL_DESCRIPTOR *)ArmGetTTBR0BaseAddress ();
@ -520,55 +525,51 @@ UpdateSectionEntries (
// EntryValue: values at bit positions specified by EntryMask
// Make sure we handle a section range that is unmapped
EntryMask = TT_DESCRIPTOR_SECTION_TYPE_MASK;
EntryMask = TT_DESCRIPTOR_SECTION_TYPE_MASK | TT_DESCRIPTOR_SECTION_XN_MASK |
TT_DESCRIPTOR_SECTION_AP_MASK;
EntryValue = TT_DESCRIPTOR_SECTION_TYPE_SECTION;
// Although the PI spec is unclear on this the GCD guarantees that only
// one Attribute bit is set at a time, so we can safely use a switch statement
switch(Attributes) {
case EFI_MEMORY_UC:
// Although the PI spec is unclear on this, the GCD guarantees that only
// one Attribute bit is set at a time, so the order of the conditionals below
// is irrelevant. If no memory attribute is specified, we preserve whatever
// memory type is set in the page tables, and update the permission attributes
// only.
if (Attributes & EFI_MEMORY_UC) {
// modify cacheability attributes
EntryMask |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_MASK;
// map to strongly ordered
EntryValue |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_STRONGLY_ORDERED; // TEX[2:0] = 0, C=0, B=0
break;
case EFI_MEMORY_WC:
} else if (Attributes & EFI_MEMORY_WC) {
// modify cacheability attributes
EntryMask |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_MASK;
// map to normal non-cachable
EntryValue |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_NON_CACHEABLE; // TEX [2:0]= 001 = 0x2, B=0, C=0
break;
case EFI_MEMORY_WT:
} else if (Attributes & EFI_MEMORY_WT) {
// modify cacheability attributes
EntryMask |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_MASK;
// write through with no-allocate
EntryValue |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_WRITE_THROUGH_NO_ALLOC; // TEX [2:0] = 0, C=1, B=0
break;
case EFI_MEMORY_WB:
} else if (Attributes & EFI_MEMORY_WB) {
// modify cacheability attributes
EntryMask |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_MASK;
// write back (with allocate)
EntryValue |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_WRITE_BACK_ALLOC; // TEX [2:0] = 001, C=1, B=1
break;
case EFI_MEMORY_WP:
case EFI_MEMORY_XP:
case EFI_MEMORY_RP:
case EFI_MEMORY_UCE:
// cannot be implemented UEFI definition unclear for ARM
// Cause a page fault if these ranges are accessed.
EntryValue = TT_DESCRIPTOR_SECTION_TYPE_FAULT;
DEBUG ((EFI_D_PAGE, "SetMemoryAttributes(): setting section %lx with unsupported attribute %x will page fault on access\n", BaseAddress, Attributes));
break;
default:
} else if (Attributes & CACHE_ATTRIBUTE_MASK) {
// catch unsupported memory type attributes
ASSERT (FALSE);
return EFI_UNSUPPORTED;
}
if (Attributes & EFI_MEMORY_RO) {
EntryValue |= TT_DESCRIPTOR_SECTION_AP_RO_RO;
} else {
EntryValue |= TT_DESCRIPTOR_SECTION_AP_RW_RW;
}
if (Attributes & EFI_MEMORY_XP) {
EntryValue |= TT_DESCRIPTOR_SECTION_XN_MASK;
}
// obtain page table base
FirstLevelTable = (ARM_FIRST_LEVEL_DESCRIPTOR *)ArmGetTTBR0BaseAddress ();
@ -697,13 +698,6 @@ SetMemoryAttributes (
return EFI_SUCCESS;
}
//
// Ignore invocations that only modify permission bits
//
if ((Attributes & EFI_MEMORY_CACHETYPE_MASK) == 0) {
return EFI_SUCCESS;
}
FlushTlbs = FALSE;
while (Length > 0) {
if ((BaseAddress % TT_DESCRIPTOR_SECTION_SIZE == 0) &&