linux-user/elfload: Implement ELF_HWCAP for RISC-V

Set I, M, A, F, D and C bit for hwcap if misa is set.

Signed-off-by: Kito Cheng <kito.cheng@sifive.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210706035015.122899-1-kito.cheng@sifive.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

linux-user/elfload.c

@@ -1434,6 +1434,19 @@ static void elf_core_copy_regs(target_elf_gregset_t *regs,
 #define ELF_CLASS ELFCLASS64
 #endif
 
+#define ELF_HWCAP get_elf_hwcap()
+
+static uint32_t get_elf_hwcap(void)
+{
+#define MISA_BIT(EXT) (1 << (EXT - 'A'))
+    RISCVCPU *cpu = RISCV_CPU(thread_cpu);
+    uint32_t mask = MISA_BIT('I') | MISA_BIT('M') | MISA_BIT('A')
+                    | MISA_BIT('F') | MISA_BIT('D') | MISA_BIT('C');
+
+    return cpu->env.misa & mask;
+#undef MISA_BIT
+}
+
 static inline void init_thread(struct target_pt_regs *regs,
                                struct image_info *infop)
 {