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ArmPkg/AsmMacroIoLibV8: remove undocumented assumption from ELx macros 

The macros EL1_OR_EL2() and EL1_OR_EL2_OR_EL3() allow conditional execution
of assembly sequences based on the current exception level, by jumping to
caller supplied labels 1f, 2f or 3f. However, the jump to 1f is actually
a fallthrough, which means the EL1 code needs to follow right after the
macro invocation, and the 1f label is ignored.

So let's fix this by making all jumps explicit.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
Reviewed-by: Eugene Cohen <eugene@hp.com>
This commit is contained in:
Ard Biesheuvel 2016-03-17 09:07:28 +01:00
parent 725cdb8fbf
commit a34608ca96
1 changed files with 8 additions and 8 deletions
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16
ArmPkg/Include/AsmMacroIoLibV8.h
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@ -24,23 +24,23 @@
#define EL1_OR_EL2(SAFE_XREG) \
mrs SAFE_XREG, CurrentEL ;\
cmp SAFE_XREG, #0x8 ;\
b.gt . ;\
b.eq 2f ;\
cmp SAFE_XREG, #0x4 ;\
b.ne . ;// We should never get here
// EL1 code starts here
cbnz SAFE_XREG, 1f ;\
b . ;// We should never get here
// CurrentEL : 0xC = EL3; 8 = EL2; 4 = EL1
// This only selects between EL1 and EL2 and EL3, else we die.
// Provide the Macro with a safe temp xreg to use.
#define EL1_OR_EL2_OR_EL3(SAFE_XREG) \
mrs SAFE_XREG, CurrentEL ;\
cmp SAFE_XREG, #0xC ;\
b.eq 3f ;\
cmp SAFE_XREG, #0x8 ;\
b.gt 3f ;\
b.eq 2f ;\
cmp SAFE_XREG, #0x4 ;\
b.ne . ;// We should never get here
// EL1 code starts here
cbnz SAFE_XREG, 1f ;\
b . ;// We should never get here
#if defined(__clang__)
// load x0 with _Data