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target/nios2: Special case ipending in rdctl and wrctl 

It was never correct to be able to write to ipending.
Until the rest of the irq code is tidied, the read of
ipending will generate an "unnecessary" mask.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2022-02-26 01:29:42 -10:00
parent 304c05df7c
commit 8d8d73b551
1 changed files with 14 additions and 0 deletions
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14
target/nios2/translate.c
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@ -452,6 +452,17 @@ static void rdctl(DisasContext *dc, uint32_t code, uint32_t flags)
}
switch (instr.imm5 + CR_BASE) {
case CR_IPENDING:
/*
* The value of the ipending register is synthetic.
* In hw, this is the AND of a set of hardware irq lines
* with the ienable register. In qemu, we re-use the space
* of CR_IPENDING to store the set of irq lines, and so we
* must perform the AND here, and anywhere else we need the
* guest value of ipending.
*/
tcg_gen_and_tl(cpu_R[instr.c], cpu_R[CR_IPENDING], cpu_R[CR_IENABLE]);
break;
default:
tcg_gen_mov_tl(cpu_R[instr.c], cpu_R[instr.imm5 + CR_BASE]);
break;
@ -477,6 +488,9 @@ static void wrctl(DisasContext *dc, uint32_t code, uint32_t flags)
case CR_TLBMISC:
gen_helper_mmu_write_tlbmisc(cpu_env, v);
break;
case CR_IPENDING:
/* ipending is read only, writes ignored. */
break;
default:
tcg_gen_mov_tl(cpu_R[instr.imm5 + CR_BASE], v);
break;