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target/mips: Add CP0_Ebase.WG (write gate) support

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Add support for the CP0_EBase.WG bit, which allows upper bits to be
written (bits 31:30 on MIPS32, or bits 63:30 on MIPS64), along with the
CP0_Config5.CV bit to control whether the exception vector for Cache
Error exceptions is forced into KSeg1.

This is necessary on MIPS32 to support Segmentation Control and Enhanced
Virtual Addressing (EVA) extensions (where KSeg1 addresses may not
represent an unmapped uncached segment).

It is also useful on MIPS64 to allow the exception base to reside in
XKPhys, and possibly out of range of KSEG0 and KSEG1.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Yongbok Kim <yongbok.kim@imgtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Reviewed-by: Yongbok Kim <yongbok.kim@imgtec.com>
[yongbok.kim@imgtec.com:
  minor changes]
Signed-off-by: Yongbok Kim <yongbok.kim@imgtec.com>
This commit is contained in:
James Hogan 2017-07-18 12:55:49 +01:00 • committed by Yongbok Kim
parent 9658e4c342
commit 74dbf824a1
6 changed files with 31 additions and 15 deletions
Download patch file Download diff file Expand all files Collapse all files

14
target/mips/helper.c
View file

@ -831,11 +831,7 @@ void mips_cpu_do_interrupt(CPUState *cs)
goto set_EPC;
case EXCP_CACHE:
cause = 30;
if (env->CP0_Status & (1 << CP0St_BEV)) {
offset = 0x100;
} else {
offset = 0x20000100;
}
offset = 0x100;
set_EPC:
if (!(env->CP0_Status & (1 << CP0St_EXL))) {
env->CP0_EPC = exception_resume_pc(env);
@ -861,9 +857,15 @@ void mips_cpu_do_interrupt(CPUState *cs)
env->hflags &= ~MIPS_HFLAG_BMASK;
if (env->CP0_Status & (1 << CP0St_BEV)) {
env->active_tc.PC = env->exception_base + 0x200;
} else if (cause == 30 && !(env->CP0_Config3 & (1 << CP0C3_SC) &&
env->CP0_Config5 & (1 << CP0C5_CV))) {
/* Force KSeg1 for cache errors */
env->active_tc.PC = (int32_t)KSEG1_BASE |
(env->CP0_EBase & 0x1FFFF000);
} else {
env->active_tc.PC = (int32_t)(env->CP0_EBase & ~0x3ff);
env->active_tc.PC = env->CP0_EBase & ~0xfff;
}
env->active_tc.PC += offset;
set_hflags_for_handler(env);
env->CP0_Cause = (env->CP0_Cause & ~(0x1f << CP0Ca_EC)) | (cause << CP0Ca_EC);