Re: [PATCH v2 3/6] target/ppc: Fix instruction loading endianness in alignment interrupt

[Anushree Mathur]

On 3/27/23 18:42, Nicholas Piggin wrote:
> powerpc ifetch endianness depends on MSR[LE] so it has to byteswap
> after cpu_ldl_code(). This corrects DSISR bits in alignment
> interrupts when running in little endian mode.
>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> Reviewed-by: Fabiano Rosas <farosas@suse.de>
> ---
> Since v1:
> - Removed big endian ifdef [Fabiano review]
> - Acaually use need_byswap helper.
>
>   target/ppc/excp_helper.c | 20 +++++++++++++++++++-
>   1 file changed, 19 insertions(+), 1 deletion(-)
>
> diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
> index 287659c74d..07729967b5 100644
> --- a/target/ppc/excp_helper.c
> +++ b/target/ppc/excp_helper.c
> @@ -133,6 +133,24 @@ static void dump_hcall(CPUPPCState *env)
>                     env->nip);
>   }
>   
> +/* Return true iff byteswap is needed in a scalar memop */
> +static inline bool need_byteswap(CPUArchState *env)
> +{
> +    /* SOFTMMU builds TARGET_BIG_ENDIAN. Need to swap when MSR[LE] is set */
> +    return !!(env->msr & ((target_ulong)1 << MSR_LE));
> +}
> +
> +static uint32_t ppc_ldl_code(CPUArchState *env, abi_ptr addr)

This hunk fails to compile with configure --disable-tcg

FAILED: libqemu-ppc64-softmmu.fa.p/target_ppc_excp_helper.c.o
cc -m64 -mlittle-endian -Ilibqemu-ppc64-softmmu.fa.p -I. -I.. 
-Itarget/ppc -I../target/ppc -I../dtc/libfdt -Iqapi -Itrace -Iui 
-Iui/shader -I/usr/include/pixman-1 -I/usr/include/glib-2.0 
-I/usr/lib64/glib-2.0/include -I/usr/include/sysprof-4 
-fdiagnostics-color=auto -Wall -Winvalid-pch -Werror -std=gnu11 -O2 -g 
-fstack-protector-strong -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -Wundef 
-Wwrite-strings -Wmissing-prototypes -Wstrict-prototypes 
-Wredundant-decls -Wold-style-declaration -Wold-style-definition 
-Wtype-limits -Wformat-security -Wformat-y2k -Winit-self 
-Wignored-qualifiers -Wempty-body -Wnested-externs -Wendif-labels 
-Wexpansion-to-defined -Wimplicit-fallthrough=2 
-Wmissing-format-attribute -Wno-missing-include-dirs 
-Wno-shift-negative-value -Wno-psabi -isystem 
/home/Shreya/qemu/linux-headers -isystem linux-headers -iquote . -iquote 
/home/Shreya/qemu -iquote /home/Shreya/qemu/include -pthread 
-D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE 
-fno-strict-aliasing -fno-common -fwrapv -fPIE -isystem../linux-headers 
-isystemlinux-headers -DNEED_CPU_H 
'-DCONFIG_TARGET="ppc64-softmmu-config-target.h"' 
'-DCONFIG_DEVICES="ppc64-softmmu-config-devices.h"' -MD -MQ 
libqemu-ppc64-softmmu.fa.p/target_ppc_excp_helper.c.o -MF 
libqemu-ppc64-softmmu.fa.p/target_ppc_excp_helper.c.o.d -o 
libqemu-ppc64-softmmu.fa.p/target_ppc_excp_helper.c.o -c 
../target/ppc/excp_helper.c
../target/ppc/excp_helper.c:143:49: error: unknown type name ‘abi_ptr’; 
did you mean ‘si_ptr’?
  143 | static uint32_t ppc_ldl_code(CPUArchState *env, abi_ptr addr)
      |                                                 ^~~~~~~
      |                                                 si_ptr
../target/ppc/excp_helper.c: In function ‘powerpc_excp_books’:
../target/ppc/excp_helper.c:1416:16: error: implicit declaration of 
function ‘ppc_ldl_code’ [-Werror=implicit-function-declaration]
 1416 |         insn = ppc_ldl_code(env, env->nip);
      |                ^~~~~~~~~~~~
../target/ppc/excp_helper.c:1416:16: error: nested extern declaration of 
‘ppc_ldl_code’ [-Werror=nested-externs]
cc1: all warnings being treated as errors

> +{
> +    uint32_t insn = cpu_ldl_code(env, addr);
> +
> +    if (need_byteswap(env)) {
> +        insn = bswap32(insn);
> +    }
> +
> +    return insn;
> +}
> +
>   static void ppc_excp_debug_sw_tlb(CPUPPCState *env, int excp)
>   {
>       const char *es;
> @@ -3097,7 +3115,7 @@ void ppc_cpu_do_unaligned_access(CPUState *cs, vaddr 
> vaddr,
>   
>       /* Restore state and reload the insn we executed, for filling in DSISR.  */
>       cpu_restore_state(cs, retaddr);
> -    insn = cpu_ldl_code(env, env->nip);
> +    insn = ppc_ldl_code(env, env->nip);
>   
>       switch (env->mmu_model) {
>       case POWERPC_MMU_SOFT_4xx:

Thanks

Anushree Mathur