summaryrefslogtreecommitdiff
path: root/arch/arm64/kernel/hyp-stub.S
diff options
context:
space:
mode:
authorMarc Zyngier <maz@kernel.org>2021-02-24 12:37:36 +0300
committerWill Deacon <will@kernel.org>2021-02-24 14:32:28 +0300
commitf1b6cff7c98be2747d2fe16e42dcdcf2fc02c7e6 (patch)
treee187d288f505f10a933b3f5956add57fabcd3791 /arch/arm64/kernel/hyp-stub.S
parent610e4dc8ac463815f5180ae2e6fadae834891b86 (diff)
downloadlinux-f1b6cff7c98be2747d2fe16e42dcdcf2fc02c7e6.tar.xz
arm64: VHE: Enable EL2 MMU from the idmap
Enabling the MMU requires the write to SCTLR_ELx (and the ISB that follows) to live in some identity-mapped memory. Otherwise, the translation will result in something totally unexpected (either fetching the wrong instruction stream, or taking a fault of some sort). This is exactly what happens in mutate_to_vhe(), as this code lives in the .hyp.text section, which isn't identity-mapped. With the right configuration, this explodes badly. Extract the MMU-enabling part of mutate_to_vhe(), and move it to its own function that lives in the idmap. This ensures nothing bad happens. Fixes: f359182291c7 ("arm64: Provide an 'upgrade to VHE' stub hypercall") Reported-by: "kernelci.org bot" <bot@kernelci.org> Tested-by: Guillaume Tucker <guillaume.tucker@collabora.com> Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20210224093738.3629662-2-maz@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/kernel/hyp-stub.S')
-rw-r--r--arch/arm64/kernel/hyp-stub.S39
1 files changed, 26 insertions, 13 deletions
diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S
index 678cd2c618ee..ae56787ea7c1 100644
--- a/arch/arm64/kernel/hyp-stub.S
+++ b/arch/arm64/kernel/hyp-stub.S
@@ -75,9 +75,6 @@ SYM_CODE_END(el1_sync)
// nVHE? No way! Give me the real thing!
SYM_CODE_START_LOCAL(mutate_to_vhe)
- // Be prepared to fail
- mov_q x0, HVC_STUB_ERR
-
// Sanity check: MMU *must* be off
mrs x1, sctlr_el2
tbnz x1, #0, 1f
@@ -96,8 +93,11 @@ SYM_CODE_START_LOCAL(mutate_to_vhe)
cmp x1, xzr
and x2, x2, x1
csinv x2, x2, xzr, ne
- cbz x2, 1f
+ cbnz x2, 2f
+1: mov_q x0, HVC_STUB_ERR
+ eret
+2:
// Engage the VHE magic!
mov_q x0, HCR_HOST_VHE_FLAGS
msr hcr_el2, x0
@@ -131,6 +131,24 @@ SYM_CODE_START_LOCAL(mutate_to_vhe)
msr mair_el1, x0
isb
+ // Hack the exception return to stay at EL2
+ mrs x0, spsr_el1
+ and x0, x0, #~PSR_MODE_MASK
+ mov x1, #PSR_MODE_EL2h
+ orr x0, x0, x1
+ msr spsr_el1, x0
+
+ b enter_vhe
+SYM_CODE_END(mutate_to_vhe)
+
+ // At the point where we reach enter_vhe(), we run with
+ // the MMU off (which is enforced by mutate_to_vhe()).
+ // We thus need to be in the idmap, or everything will
+ // explode when enabling the MMU.
+
+ .pushsection .idmap.text, "ax"
+
+SYM_CODE_START_LOCAL(enter_vhe)
// Invalidate TLBs before enabling the MMU
tlbi vmalle1
dsb nsh
@@ -143,17 +161,12 @@ SYM_CODE_START_LOCAL(mutate_to_vhe)
mov_q x0, INIT_SCTLR_EL1_MMU_OFF
msr_s SYS_SCTLR_EL12, x0
- // Hack the exception return to stay at EL2
- mrs x0, spsr_el1
- and x0, x0, #~PSR_MODE_MASK
- mov x1, #PSR_MODE_EL2h
- orr x0, x0, x1
- msr spsr_el1, x0
-
mov x0, xzr
-1: eret
-SYM_CODE_END(mutate_to_vhe)
+ eret
+SYM_CODE_END(enter_vhe)
+
+ .popsection
.macro invalid_vector label
SYM_CODE_START_LOCAL(\label)