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author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2016-09-09 10:52:25 +0100 |
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committer | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2016-09-13 13:42:57 +0100 |
commit | e93cb72e597df7b37aad7910787b8ecaeac31382 (patch) | |
tree | 619edd9cc706d557b3049f69161c85e6a1d6fa11 | |
parent | b6b33f67dfc6e81dbbdd10c102f2665e7472cd4d (diff) | |
download | edk2-e93cb72e597df7b37aad7910787b8ecaeac31382.tar.gz edk2-e93cb72e597df7b37aad7910787b8ecaeac31382.tar.bz2 edk2-e93cb72e597df7b37aad7910787b8ecaeac31382.zip |
ArmPkg/ArmMmuLib: deobfuscate GetRootTranslationTableInfo ()
The relations between T0SZ, the number of translation levels and the
size/alignment of the root table can be expressed in simple arithmetic
expressions, so get rid of the lookup table.
Note that this disregards the fact that the maximum value of T0SZ is
39 not 42 (as one would expect for the smallest VA size using 2 levels)
but since this corresponds to a VA size of 32 MB and 4 MB, respectively,
neither of which are sufficient to run UEFI, we can safely ignore the
distinction.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
-rw-r--r-- | ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c | 35 |
1 files changed, 4 insertions, 31 deletions
diff --git a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c index 6e05e60850..84a689af7c 100644 --- a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c +++ b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c @@ -121,20 +121,8 @@ GcdAttributeToArmAttribute ( }
}
-// Describe the T0SZ values for each translation table level
-typedef struct {
- UINTN MinT0SZ;
- UINTN MaxT0SZ;
- UINTN LargestT0SZ; // Generally (MaxT0SZ == LargestT0SZ) but at the Level3 Table
- // the MaxT0SZ is not at the boundary of the table
-} T0SZ_DESCRIPTION_PER_LEVEL;
-
-// Map table for the corresponding Level of Table
-STATIC CONST T0SZ_DESCRIPTION_PER_LEVEL T0SZPerTableLevel[] = {
- { 16, 24, 24 }, // Table Level 0
- { 25, 33, 33 }, // Table Level 1
- { 34, 39, 42 } // Table Level 2
-};
+#define MIN_T0SZ 16
+#define BITS_PER_LEVEL 9
VOID
GetRootTranslationTableInfo (
@@ -143,28 +131,13 @@ GetRootTranslationTableInfo ( OUT UINTN *TableEntryCount
)
{
- UINTN Index;
-
- // Identify the level of the root table from the given T0SZ
- for (Index = 0; Index < sizeof (T0SZPerTableLevel) / sizeof (T0SZ_DESCRIPTION_PER_LEVEL); Index++) {
- if (T0SZ <= T0SZPerTableLevel[Index].MaxT0SZ) {
- break;
- }
- }
-
- // If we have not found the corresponding maximum T0SZ then we use the last one
- if (Index == sizeof (T0SZPerTableLevel) / sizeof (T0SZ_DESCRIPTION_PER_LEVEL)) {
- Index--;
- }
-
// Get the level of the root table
if (TableLevel) {
- *TableLevel = Index;
+ *TableLevel = (T0SZ - MIN_T0SZ) / BITS_PER_LEVEL;
}
- // The Size of the Table is 2^(T0SZ-LargestT0SZ)
if (TableEntryCount) {
- *TableEntryCount = 1 << (T0SZPerTableLevel[Index].LargestT0SZ - T0SZ + 1);
+ *TableEntryCount = 1UL << (BITS_PER_LEVEL - (T0SZ - MIN_T0SZ) % BITS_PER_LEVEL);
}
}
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