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target/ppc: Ease L=0 requirement on cmp/cmpi/cmpl/cmpli for ppc32 

In commit 8f0a4b6a9b, we started to require L=0 for ppc32 to match what
The Programming Environments Manual say:

"For 32-bit implementations, the L field must be cleared, otherwise
the instruction form is invalid."

The stricter behavior, however, broke AROS boot on sam460ex, which is a
regression from 6.0. This patch partially reverts the change, raising
the exception only for CPUs known to require L=0 (e500 and e500mc) and
logging a guest error for other cases.

Both behaviors are acceptable by the PowerISA, which allows "the system
illegal instruction error handler to be invoked or yield boundedly
undefined results."

Reported-by: BALATON Zoltan <balaton@eik.bme.hu>
Fixes: 8f0a4b6a9b ("target/ppc: Move cmp/cmpi/cmpl/cmpli to decodetree")
Tested-by: BALATON Zoltan <balaton@eik.bme.hu>
Signed-off-by: Matheus Ferst <matheus.ferst@eldorado.org.br>
Message-Id: <20210720135507.2444635-1-matheus.ferst@eldorado.org.br>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Matheus Ferst 2021-07-20 10:55:07 -03:00 committed by David Gibson
parent 793abe24aa
commit 2d1154bd95
1 changed files with 56 additions and 2 deletions
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58
target/ppc/translate/fixedpoint-impl.c.inc
View File

@ -171,8 +171,35 @@ TRANS64(PSTD, do_ldst_PLS_D, false, true, MO_Q)
static bool do_cmp_X(DisasContext *ctx, arg_X_bfl *a, bool s)
{
if ((ctx->insns_flags & PPC_64B) == 0) {
/*
* For 32-bit implementations, The Programming Environments Manual says
* that "the L field must be cleared, otherwise the instruction form is
* invalid." It seems, however, that most 32-bit CPUs ignore invalid
* forms (e.g., section "Instruction Formats" of the 405 and 440
* manuals, "Integer Compare Instructions" of the 601 manual), with the
* notable exception of the e500 and e500mc, where L=1 was reported to
* cause an exception.
*/
if (a->l) {
if ((ctx->insns_flags2 & PPC2_BOOKE206)) {
/*
* For 32-bit Book E v2.06 implementations (i.e. e500/e500mc),
* generate an illegal instruction exception.
*/
return false;
} else {
qemu_log_mask(LOG_GUEST_ERROR,
"Invalid form of CMP%s at 0x" TARGET_FMT_lx ", L = 1\n",
s ? "" : "L", ctx->cia);
}
}
gen_op_cmp32(cpu_gpr[a->ra], cpu_gpr[a->rb], s, a->bf);
return true;
}
/* For 64-bit implementations, deal with bit L accordingly. */
if (a->l) {
REQUIRE_64BIT(ctx);
gen_op_cmp(cpu_gpr[a->ra], cpu_gpr[a->rb], s, a->bf);
} else {
gen_op_cmp32(cpu_gpr[a->ra], cpu_gpr[a->rb], s, a->bf);
@ -182,8 +209,35 @@ static bool do_cmp_X(DisasContext *ctx, arg_X_bfl *a, bool s)
static bool do_cmp_D(DisasContext *ctx, arg_D_bf *a, bool s)
{
if ((ctx->insns_flags & PPC_64B) == 0) {
/*
* For 32-bit implementations, The Programming Environments Manual says
* that "the L field must be cleared, otherwise the instruction form is
* invalid." It seems, however, that most 32-bit CPUs ignore invalid
* forms (e.g., section "Instruction Formats" of the 405 and 440
* manuals, "Integer Compare Instructions" of the 601 manual), with the
* notable exception of the e500 and e500mc, where L=1 was reported to
* cause an exception.
*/
if (a->l) {
if ((ctx->insns_flags2 & PPC2_BOOKE206)) {
/*
* For 32-bit Book E v2.06 implementations (i.e. e500/e500mc),
* generate an illegal instruction exception.
*/
return false;
} else {
qemu_log_mask(LOG_GUEST_ERROR,
"Invalid form of CMP%s at 0x" TARGET_FMT_lx ", L = 1\n",
s ? "I" : "LI", ctx->cia);
}
}
gen_op_cmp32(cpu_gpr[a->ra], tcg_constant_tl(a->imm), s, a->bf);
return true;
}
/* For 64-bit implementations, deal with bit L accordingly. */
if (a->l) {
REQUIRE_64BIT(ctx);
gen_op_cmp(cpu_gpr[a->ra], tcg_constant_tl(a->imm), s, a->bf);
} else {
gen_op_cmp32(cpu_gpr[a->ra], tcg_constant_tl(a->imm), s, a->bf);