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arch-arm: Read APSR in User Mode

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This patch substitutes reads to the CPSR in user mode (MRS CPSR) to
reads to APSR (Application Program Status Register).
This is the user level alias for the CPSR. The APSR is a subset of the
CPSR.

Change-Id: I18a70693aef6fd305a4c4cb3c6f81f331bc60a2d
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/10602
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
This commit is contained in:
Giacomo Travaglini
2018-04-30 17:13:54 +01:00
parent 4a37134f5f
commit 831184d294
2 changed files with 12 additions and 1 deletions
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2
src/arch/arm/isa/insts/misc.isa
View File

@@ -226,7 +226,7 @@ let {{
cpsr.c = CondCodesC;
cpsr.v = CondCodesV;
cpsr.ge = CondCodesGE;
Dest = cpsr & 0xF8FF03DF
Dest = cpsr & (cpsr.mode == MODE_USER ? ApsrMask : CpsrMask);
'''
mrsCpsrIop = InstObjParams("mrs", "MrsCpsr", "MrsOp",

11
src/arch/arm/miscregs.hh
View File

@@ -1423,6 +1423,17 @@ namespace ArmISA
static const uint32_t CondCodesMask = 0xF00F0000;
static const uint32_t CpsrMaskQ = 0x08000000;
// APSR (Application Program Status Register Mask). It is the user level
// alias for the CPSR. The APSR is a subset of the CPSR. Although
// bits[15:0] are UNKNOWN on reads, it is permitted that, on a read of
// APSR:
// Bit[9] returns the value of CPSR.E.
// Bits[8:6] return the value of CPSR.{A,I, F}, the mask bits.
static const uint32_t ApsrMask = CpsrMaskQ | CondCodesMask | 0x000001D0;
// CPSR (Current Program Status Register Mask).
static const uint32_t CpsrMask = ApsrMask | 0x00F003DF;
BitUnion32(HDCR)
Bitfield<11> tdra;
Bitfield<10> tdosa;