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| author | Marc Zyngier <maz@kernel.org> | 2021-02-24 09:37:36 +0000 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2021-02-24 11:32:28 +0000 |
| commit | f1b6cff7c98be2747d2fe16e42dcdcf2fc02c7e6 (patch) | |
| tree | e187d288f505f10a933b3f5956add57fabcd3791 /arch/arm64/kernel/hyp-stub.S | |
| parent | 610e4dc8ac463815f5180ae2e6fadae834891b86 (diff) | |
| download | linux-f1b6cff7c98be2747d2fe16e42dcdcf2fc02c7e6.tar.bz2 | |
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.S | 39 |
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) |