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Subject[ 15/89] ARM: virt: simplify __hyp_stub_install epilog
Date
3.7-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Marc Zyngier <marc.zyngier@arm.com>

commit d01723479e6a6c70c83295f7847477a016d5e14a upstream.

__hyp_stub_install duplicates quite a bit of safe_svcmode_maskall
by forcing the CPU back to SVC. This is unnecessary, as
safe_svcmode_maskall is called just after.

Furthermore, the way we build SPSR_hyp is buggy as we fail to mask
the interrupts, leading to interesting behaviours on TC2 + UEFI.

The fix is to simply remove this code and rely on safe_svcmode_maskall
to do the right thing.

Reviewed-by: Dave Martin <dave.martin@linaro.org>
Reported-by: Harry Liebel <harry.liebel@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/arm/kernel/hyp-stub.S | 12 +++---------
1 file changed, 3 insertions(+), 9 deletions(-)

--- a/arch/arm/kernel/hyp-stub.S
+++ b/arch/arm/kernel/hyp-stub.S
@@ -120,7 +120,8 @@ ENTRY(__hyp_stub_install_secondary)
* Eventually, CPU-specific code might be needed -- assume not for now
*
* This code relies on the "eret" instruction to synchronize the
- * various coprocessor accesses.
+ * various coprocessor accesses. This is done when we switch to SVC
+ * (see safe_svcmode_maskall).
*/
@ Now install the hypervisor stub:
adr r7, __hyp_stub_vectors
@@ -155,14 +156,7 @@ THUMB( orr r7, #(1 << 30) ) @ HSCTLR.TE
1:
#endif

- bic r7, r4, #MODE_MASK
- orr r7, r7, #SVC_MODE
-THUMB( orr r7, r7, #PSR_T_BIT )
- msr spsr_cxsf, r7 @ This is SPSR_hyp.
-
- __MSR_ELR_HYP(14) @ msr elr_hyp, lr
- __ERET @ return, switching to SVC mode
- @ The boot CPU mode is left in r4.
+ bx lr @ The boot CPU mode is left in r4.
ENDPROC(__hyp_stub_install_secondary)

__hyp_stub_do_trap:



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