[PATCH] linux-user: Fix mips fp64 executables loading

[PATCH] linux-user: Fix mips fp64 executables loading

[Daniil Kovalev]

If a program requires fr1, we should set the FR bit of CP0 control status
register and add F64 hardware flag. The corresponding `else if` branch
statement is copied from the linux kernel sources (see `arch_check_elf` function
in linux/arch/mips/kernel/elf.c).

Signed-off-by: Daniil Kovalev <dkovalev@compiler-toolchain-for.me>
---
 linux-user/mips/cpu_loop.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/linux-user/mips/cpu_loop.c b/linux-user/mips/cpu_loop.c
index d5c1c7941d..8735e58bad 100644
--- a/linux-user/mips/cpu_loop.c
+++ b/linux-user/mips/cpu_loop.c
@@ -290,7 +290,10 @@ void target_cpu_copy_regs(CPUArchState *env, struct target_pt_regs *regs)
             env->CP0_Status |= (1 << CP0St_FR);
             env->hflags |= MIPS_HFLAG_F64;
         }
-    } else  if (!prog_req.fre && !prog_req.frdefault &&
+    } else if (prog_req.fr1) {
+        env->CP0_Status |= (1 << CP0St_FR);
+        env->hflags |= MIPS_HFLAG_F64;
+    } else if (!prog_req.fre && !prog_req.frdefault &&
           !prog_req.fr1 && !prog_req.single && !prog_req.soft) {
         fprintf(stderr, "qemu: Can't find a matching FPU mode\n");
         exit(1);
-- 
2.40.0

Re: [PATCH] linux-user: Fix mips fp64 executables loading

[Jiaxun Yang]

> 2023年4月4日 06:21，Daniil Kovalev <dkovalev@compiler-toolchain-for.me> 写道：
> 
> If a program requires fr1, we should set the FR bit of CP0 control status
> register and add F64 hardware flag. The corresponding `else if` branch
> statement is copied from the linux kernel sources (see `arch_check_elf` function
> in linux/arch/mips/kernel/elf.c).
> 
> Signed-off-by: Daniil Kovalev <dkovalev@compiler-toolchain-for.me>

Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>

Thanks!

> ---
> linux-user/mips/cpu_loop.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/linux-user/mips/cpu_loop.c b/linux-user/mips/cpu_loop.c
> index d5c1c7941d..8735e58bad 100644
> --- a/linux-user/mips/cpu_loop.c
> +++ b/linux-user/mips/cpu_loop.c
> @@ -290,7 +290,10 @@ void target_cpu_copy_regs(CPUArchState *env, struct target_pt_regs *regs)
>             env->CP0_Status |= (1 << CP0St_FR);
>             env->hflags |= MIPS_HFLAG_F64;
>         }
> -    } else  if (!prog_req.fre && !prog_req.frdefault &&
> +    } else if (prog_req.fr1) {
> +        env->CP0_Status |= (1 << CP0St_FR);
> +        env->hflags |= MIPS_HFLAG_F64;
> +    } else if (!prog_req.fre && !prog_req.frdefault &&
>           !prog_req.fr1 && !prog_req.single && !prog_req.soft) {
>         fprintf(stderr, "qemu: Can't find a matching FPU mode\n");
>         exit(1);
> -- 
> 2.40.0
> 

Re: [PATCH] linux-user: Fix mips fp64 executables loading

[Laurent Vivier]

Le 04/04/2023 à 07:21, Daniil Kovalev a écrit :
> If a program requires fr1, we should set the FR bit of CP0 control status
> register and add F64 hardware flag. The corresponding `else if` branch
> statement is copied from the linux kernel sources (see `arch_check_elf` function
> in linux/arch/mips/kernel/elf.c).
> 
> Signed-off-by: Daniil Kovalev <dkovalev@compiler-toolchain-for.me>
> ---
>   linux-user/mips/cpu_loop.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/linux-user/mips/cpu_loop.c b/linux-user/mips/cpu_loop.c
> index d5c1c7941d..8735e58bad 100644
> --- a/linux-user/mips/cpu_loop.c
> +++ b/linux-user/mips/cpu_loop.c
> @@ -290,7 +290,10 @@ void target_cpu_copy_regs(CPUArchState *env, struct target_pt_regs *regs)
>               env->CP0_Status |= (1 << CP0St_FR);
>               env->hflags |= MIPS_HFLAG_F64;
>           }
> -    } else  if (!prog_req.fre && !prog_req.frdefault &&
> +    } else if (prog_req.fr1) {
> +        env->CP0_Status |= (1 << CP0St_FR);
> +        env->hflags |= MIPS_HFLAG_F64;
> +    } else if (!prog_req.fre && !prog_req.frdefault &&
>             !prog_req.fr1 && !prog_req.single && !prog_req.soft) {
>           fprintf(stderr, "qemu: Can't find a matching FPU mode\n");
>           exit(1);

Applied to my linux-user-for-8.1 branch.

Thanks,
Laurent

Re: [PATCH] linux-user: Fix mips fp64 executables loading

[Michael Tokarev]

04.04.2023 08:21, Daniil Kovalev Wrote:
> If a program requires fr1, we should set the FR bit of CP0 control status
> register and add F64 hardware flag. The corresponding `else if` branch
> statement is copied from the linux kernel sources (see `arch_check_elf` function
> in linux/arch/mips/kernel/elf.c).

Is it a -stable material?

Thanks,

/mjt

Re: [PATCH] linux-user: Fix mips fp64 executables loading

[Daniil Kovalev]

Hello,

On Tue, 2 May 2023 14:41:31 +0300
Michael Tokarev <mjt@tls.msk.ru> wrote:

> Is it a -stable material?

Yes, this `else if` branch is present in the latest linux-stable. It was
actually introduced in 46490b572544fa908be051f7872beb2941e55ede in 2015 and
never changed since then. I suppose that just a dummy typo error occurred when
copying that to qemu-user loader: this piece of code never changed in the linux
kernel since initially committed, so this particular `else if` branch just
seems to be forgotten when copying.

Best regards, Daniil Kovalev