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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2020-02-26 09:40:33 +0100
committermergify[bot] <37929162+mergify[bot]@users.noreply.github.com>2020-03-05 21:08:30 +0000
commit3391e20ffa3fc4cb34d4b19c28922f7e7b0edf45 (patch)
tree4e6a444342f7d4cfd2bd672f5057a5e3439d2e29
parent02d7797d1a2c46ca140bade48aefb366813c2ce8 (diff)
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ArmPkg/ArmMmuLib AARCH64: cache-invalidate initial page table entries
In the AARCH64 version of ArmMmuLib, we are currently relying on set/way invalidation to ensure that the caches are in a consistent state with respect to main memory once we turn the MMU on. Even if set/way operations were the appropriate method to achieve this, doing an invalidate-all first and then populating the page table entries creates a window where page table entries could be loaded speculatively into the caches before we modify them, and shadow the new values that we write there. So let's get rid of the blanket clean/invalidate operations, and instead, update ArmUpdateTranslationTableEntry () to invalidate each page table entry *after* it is written if the MMU is still disabled at this point. On ARMv8, it is guaranteed that memory accesses done by the page table walker are cache coherent, and so we can ignore the case where the MMU is on. Since the MMU and D-cache are already off when we reach this point, we can drop the MMU and D-cache disables as well. Maintenance of the I-cache is unnecessary, since we are not modifying any code, and the installed mapping is guaranteed to be 1:1. This means we can also leave it enabled while the page table population code is running. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Leif Lindholm <leif@nuviainc.com>
-rw-r--r--ArmPkg/Library/ArmLib/AArch64/ArmLibSupport.S9
-rw-r--r--ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c9
2 files changed, 8 insertions, 10 deletions
diff --git a/ArmPkg/Library/ArmLib/AArch64/ArmLibSupport.S b/ArmPkg/Library/ArmLib/AArch64/ArmLibSupport.S
index 1adf960377..f744cd6738 100644
--- a/ArmPkg/Library/ArmLib/AArch64/ArmLibSupport.S
+++ b/ArmPkg/Library/ArmLib/AArch64/ArmLibSupport.S
@@ -13,6 +13,8 @@
.set DAIF_RD_FIQ_BIT, (1 << 6)
.set DAIF_RD_IRQ_BIT, (1 << 7)
+.set SCTLR_ELx_M_BIT_POS, (0)
+
ASM_FUNC(ArmReadMidr)
mrs x0, midr_el1 // Read from Main ID Register (MIDR)
ret
@@ -122,11 +124,16 @@ ASM_FUNC(ArmUpdateTranslationTableEntry)
lsr x1, x1, #12
EL1_OR_EL2_OR_EL3(x0)
1: tlbi vaae1, x1 // TLB Invalidate VA , EL1
+ mrs x2, sctlr_el1
b 4f
2: tlbi vae2, x1 // TLB Invalidate VA , EL2
+ mrs x2, sctlr_el2
b 4f
3: tlbi vae3, x1 // TLB Invalidate VA , EL3
-4: dsb nsh
+ mrs x2, sctlr_el3
+4: tbnz x2, SCTLR_ELx_M_BIT_POS, 5f
+ dc ivac, x0 // invalidate in Dcache if MMU is still off
+5: dsb nsh
isb
ret
diff --git a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
index e8f5c69e31..204e33c75f 100644
--- a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
+++ b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
@@ -699,15 +699,6 @@ ArmConfigureMmu (
ZeroMem (TranslationTable, RootTableEntryCount * sizeof(UINT64));
- // Disable MMU and caches. ArmDisableMmu() also invalidates the TLBs
- ArmDisableMmu ();
- ArmDisableDataCache ();
- ArmDisableInstructionCache ();
-
- // Make sure nothing sneaked into the cache
- ArmCleanInvalidateDataCache ();
- ArmInvalidateInstructionCache ();
-
TranslationTableAttribute = TT_ATTR_INDX_INVALID;
while (MemoryTable->Length != 0) {