@@ -1,70 +1,147 @@
-target/ppc: Fix fallback to MFSS for MFFSCRN, MFFSCRNI, MFFSCE and MFFSL
+From d92b63b7d15d4fd202c5802dfe444a96f5d8109c Mon Sep 17 00:00:00 2001
+From: Richard Purdie <richard.purdie@linuxfoundation.org>
+Date: Sat, 6 May 2023 07:42:35 +0100
+Cc: Víctor Colombo <victor.colombo@eldorado.org.br>
+Cc: Matheus Ferst <matheus.ferst@eldorado.org.br>
+Cc: Daniel Henrique Barboza <danielhb413@gmail.com>
+Cc: Richard Henderson <richard.henderson@linaro.org>
+Subject: [PATCH v2] target/ppc: Fix fallback to MFSS for MFFS* instructions on
+ pre 3.0 ISAs
-The following commits changed the code such that these instructions became invalid
-on pre 3.0 ISAs:
+The following commits changed the code such that the fallback to MFSS for MFFSCRN,
+MFFSCRNI, MFFSCE and MFFSL on pre 3.0 ISAs was removed and became an illegal instruction:
- bf8adfd88b547680aa857c46098f3a1e94373160 - target/ppc: Move mffscrn[i] to decodetree
+ bf8adfd88b547680aa857c46098f3a1e94373160 - target/ppc: Move mffscrn[i] to decodetree
394c2e2fda70da722f20fb60412d6c0ca4bfaa03 - target/ppc: Move mffsce to decodetree
- 3e5bce70efe6bd1f684efbb21fd2a316cbf0657e - target/ppc: Move mffsl to decodetree
+ 3e5bce70efe6bd1f684efbb21fd2a316cbf0657e - target/ppc: Move mffsl to decodetree
The hardware will handle them as a MFFS instruction as the code did previously.
-Restore that behaviour. This means applications that were segfaulting under qemu
-when encountering these instructions now operate correctly. The instruction
-is used in glibc libm functions for example.
+This means applications that were segfaulting under qemu when encountering these
+instructions which is used in glibc libm functions for example.
-Upstream-Status: Submitted [https://lore.kernel.org/qemu-devel/20230504110150.3044402-1-richard.purdie@linuxfoundation.org/]
+The fallback for MFFSCDRN and MFFSCDRNI added in a later patch was also missing.
+
+This patch restores the fallback to MFSS for these instructions on pre 3.0s ISAs
+as the hardware decoder would, fixing the segfaulting libm code. It and also ensures
+the MFSS instruction is used for currently reserved bits to handle other potential
+ISA additions more correctly.
+
+Upstream-Status: Submitted [https://lore.kernel.org/qemu-devel/20230506065240.3177798-1-richard.purdie@linuxfoundation.org/]
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
+---
+ target/ppc/insn32.decode | 19 ++++++++++++-------
+ target/ppc/translate/fp-impl.c.inc | 30 ++++++++++++++++++++++++------
+ 2 files changed, 36 insertions(+), 13 deletions(-)
-Index: qemu-8.0.0/target/ppc/translate/fp-impl.c.inc
-===================================================================
---- qemu-8.0.0.orig/target/ppc/translate/fp-impl.c.inc
-+++ qemu-8.0.0/target/ppc/translate/fp-impl.c.inc
-@@ -584,7 +584,10 @@ static bool trans_MFFSCE(DisasContext *c
+v2 - switch to use decodetree pattern groups per feedback
+
+diff --git a/target/ppc/insn32.decode b/target/ppc/insn32.decode
+index f8f589e9fd..3c4e2c2fc2 100644
+--- a/target/ppc/insn32.decode
++++ b/target/ppc/insn32.decode
+@@ -390,13 +390,18 @@ SETNBCR 011111 ..... ..... ----- 0111100000 - @X_bi
+
+ ### Move To/From FPSCR
+
+-MFFS 111111 ..... 00000 ----- 1001000111 . @X_t_rc
+-MFFSCE 111111 ..... 00001 ----- 1001000111 - @X_t
+-MFFSCRN 111111 ..... 10110 ..... 1001000111 - @X_tb
+-MFFSCDRN 111111 ..... 10100 ..... 1001000111 - @X_tb
+-MFFSCRNI 111111 ..... 10111 ---.. 1001000111 - @X_imm2
+-MFFSCDRNI 111111 ..... 10101 --... 1001000111 - @X_imm3
+-MFFSL 111111 ..... 11000 ----- 1001000111 - @X_t
++{
++ # Before Power ISA v3.0, MFFS bits 11~15 were reserved and should be ignored
++ [
++ MFFSCE 111111 ..... 00001 ----- 1001000111 - @X_t
++ MFFSCRN 111111 ..... 10110 ..... 1001000111 - @X_tb
++ MFFSCDRN 111111 ..... 10100 ..... 1001000111 - @X_tb
++ MFFSCRNI 111111 ..... 10111 ---.. 1001000111 - @X_imm2
++ MFFSCDRNI 111111 ..... 10101 --... 1001000111 - @X_imm3
++ MFFSL 111111 ..... 11000 ----- 1001000111 - @X_t
++ ]
++ MFFS 111111 ..... ----- ----- 1001000111 . @X_t_rc
++}
+
+ ### Decimal Floating-Point Arithmetic Instructions
+
+diff --git a/target/ppc/translate/fp-impl.c.inc b/target/ppc/translate/fp-impl.c.inc
+index 57d8437851..10dfd91aa4 100644
+--- a/target/ppc/translate/fp-impl.c.inc
++++ b/target/ppc/translate/fp-impl.c.inc
+@@ -584,7 +584,10 @@ static bool trans_MFFSCE(DisasContext *ctx, arg_X_t *a)
{
TCGv_i64 fpscr;
- REQUIRE_INSNS_FLAGS2(ctx, ISA300);
-+ if (unlikely(!(ctx->insns_flags2 & PPC2_ISA300))) {
-+ return trans_MFFS(ctx, a);
++ if (!(ctx->insns_flags2 & PPC2_ISA300)) {
++ return false;
+ }
+
REQUIRE_FPU(ctx);
gen_reset_fpstatus();
-@@ -597,7 +600,10 @@ static bool trans_MFFSCRN(DisasContext *
+@@ -597,7 +600,10 @@ static bool trans_MFFSCRN(DisasContext *ctx, arg_X_tb *a)
+ {
+ TCGv_i64 t1, fpscr;
+
+- REQUIRE_INSNS_FLAGS2(ctx, ISA300);
++ if (!(ctx->insns_flags2 & PPC2_ISA300)) {
++ return false;
++ }
++
+ REQUIRE_FPU(ctx);
+
+ t1 = tcg_temp_new_i64();
+@@ -614,7 +620,10 @@ static bool trans_MFFSCDRN(DisasContext *ctx, arg_X_tb *a)
{
TCGv_i64 t1, fpscr;
- REQUIRE_INSNS_FLAGS2(ctx, ISA300);
-+ if (unlikely(!(ctx->insns_flags2 & PPC2_ISA300))) {
-+ return trans_MFFS(ctx, a);
++ if (!(ctx->insns_flags2 & PPC2_ISA300)) {
++ return false;
+ }
+
REQUIRE_FPU(ctx);
t1 = tcg_temp_new_i64();
-@@ -631,7 +637,10 @@ static bool trans_MFFSCRNI(DisasContext
+@@ -631,7 +640,10 @@ static bool trans_MFFSCRNI(DisasContext *ctx, arg_X_imm2 *a)
{
TCGv_i64 t1, fpscr;
- REQUIRE_INSNS_FLAGS2(ctx, ISA300);
-+ if (unlikely(!(ctx->insns_flags2 & PPC2_ISA300))) {
-+ return trans_MFFS(ctx, a);
++ if (!(ctx->insns_flags2 & PPC2_ISA300)) {
++ return false;
+ }
+
REQUIRE_FPU(ctx);
t1 = tcg_temp_new_i64();
-@@ -661,7 +670,10 @@ static bool trans_MFFSCDRNI(DisasContext
+@@ -647,7 +659,10 @@ static bool trans_MFFSCDRNI(DisasContext *ctx, arg_X_imm3 *a)
+ {
+ TCGv_i64 t1, fpscr;
+
+- REQUIRE_INSNS_FLAGS2(ctx, ISA300);
++ if (!(ctx->insns_flags2 & PPC2_ISA300)) {
++ return false;
++ }
++
+ REQUIRE_FPU(ctx);
+
+ t1 = tcg_temp_new_i64();
+@@ -661,7 +676,10 @@ static bool trans_MFFSCDRNI(DisasContext *ctx, arg_X_imm3 *a)
static bool trans_MFFSL(DisasContext *ctx, arg_X_t *a)
{
- REQUIRE_INSNS_FLAGS2(ctx, ISA300);
-+ if (unlikely(!(ctx->insns_flags2 & PPC2_ISA300))) {
-+ return trans_MFFS(ctx, a);
++ if (!(ctx->insns_flags2 & PPC2_ISA300)) {
++ return false;
+ }
+
REQUIRE_FPU(ctx);
gen_reset_fpstatus();
+--
+2.39.2
+
Upstream asked for some changes, this updates our patch to match. The differences likely don't change our real world use. Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org> --- meta/recipes-devtools/qemu/qemu/ppc.patch | 127 +++++++++++++++++----- 1 file changed, 102 insertions(+), 25 deletions(-)