Re: [PATCH 2/2] linux-user: Set ELF_BASE_PLATFORM for MIPS

[Philippe Mathieu-Daudé]

On 1/8/22 22:09, Jiaxun Yang wrote:

"On MIPS, AT_BASE_PLATFORM identifies the ISA level (since Linux 5.7)."

> Match most appropriate base platform string based on insn_flags.
> Logic is aligned with arch/mips/kernel/cpu-probe.c in Linux kernel.
"... aligned with set_isa() from ..."

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> ---
>   linux-user/elfload.c | 31 +++++++++++++++++++++++++++++++
>   1 file changed, 31 insertions(+)
>
> diff --git a/linux-user/elfload.c b/linux-user/elfload.c
> index e7666c5c60..8a4ac9787f 100644
> --- a/linux-user/elfload.c
> +++ b/linux-user/elfload.c
> @@ -1050,6 +1050,37 @@ static uint32_t get_elf_hwcap(void)
>   #define elf_check_abi(x) (!((x) & EF_MIPS_ABI2))
>   #endif
>   
> +#define ELF_BASE_PLATFORM get_elf_base_platform()
> +
> +#define MATCH_PLATFORM_INSN(_flags, _base_platform)      \
> +    do { if ((cpu->env.insn_flags & (_flags)) == _flags) \
> +    { return _base_platform; } } while (0)
> +
> +static const char *get_elf_base_platform(void)
> +{
> +    MIPSCPU *cpu = MIPS_CPU(thread_cpu);
> +
> +    /* 64 bit ISAs goes first */
> +    MATCH_PLATFORM_INSN(CPU_MIPS64R6, "mips64r6");
> +    MATCH_PLATFORM_INSN(CPU_MIPS64R5, "mips64r5");
> +    MATCH_PLATFORM_INSN(CPU_MIPS64R2, "mips64r2");
> +    MATCH_PLATFORM_INSN(CPU_MIPS64R1, "mips64");
> +    MATCH_PLATFORM_INSN(CPU_MIPS5, "mips5");
> +    MATCH_PLATFORM_INSN(CPU_MIPS4, "mips4");
> +    MATCH_PLATFORM_INSN(CPU_MIPS3, "mips3");
> +
> +    /* 32 bit ISAs */
> +    MATCH_PLATFORM_INSN(CPU_MIPS32R6, "mips32r6");
> +    MATCH_PLATFORM_INSN(CPU_MIPS32R5, "mips32r5");
> +    MATCH_PLATFORM_INSN(CPU_MIPS32R2, "mips32r2");
> +    MATCH_PLATFORM_INSN(CPU_MIPS32R1, "mips32");
> +    MATCH_PLATFORM_INSN(CPU_MIPS2, "mips2");
> +
> +    /* Fallback */
> +    return "mips";
> +}
> +#undef MATCH_PLATFORM_INSN
> +
>   static inline void init_thread(struct target_pt_regs *regs,
>                                  struct image_info *infop)
>   {