commit 5836c3eccedb6dfab16b8f606f2de24b8938b69c
author Kito Cheng <kito.cheng@gmail.com> Sat Mar 16 01:20:46 2019 +0000
committer Palmer Dabbelt <palmer@sifive.com> Tue Mar 19 05:14:39 2019 -0700
tree 06b0788af46c10271d0d2781acb90a7a8cfebbcf
parent c02b78c7b4cecfe0a027abff8ecc3ec02e8b4a53

RISC-V: linux-user support for RVE ABI

This change checks elf_flags for EF_RISCV_RVE and if
present uses the RVE linux syscall ABI which uses t0
for the syscall number instead of a7.

Warn and exit if a non-RVE ABI binary is run on a
cpu with the RVE extension as it is incompatible.

Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Sagar Karandikar <sagark@eecs.berkeley.edu>
Cc: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
Cc: Alistair Francis <Alistair.Francis@wdc.com>
Co-authored-by: Kito Cheng <kito.cheng@gmail.com>
Co-authored-by: Michael Clark <mjc@sifive.com>
Signed-off-by: Michael Clark <mjc@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

linux-user/riscv/cpu_loop.c

diff --git a/linux-user/riscv/cpu_loop.c b/linux-user/riscv/cpu_loop.c
index 4cf3e94..a9bac4c 100644
--- a/linux-user/riscv/cpu_loop.c
+++ b/linux-user/riscv/cpu_loop.c
@@ -18,8 +18,10 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu/error-report.h"
 #include "qemu.h"
 #include "cpu_loop-common.h"
+#include "elf.h"
 
 void cpu_loop(CPURISCVState *env)
 {
@@ -53,7 +55,8 @@
                 ret = 0;
             } else {
                 ret = do_syscall(env,
-                                 env->gpr[xA7],
+                                 env->gpr[(env->elf_flags & EF_RISCV_RVE)
+                                    ? xT0 : xA7],
                                  env->gpr[xA0],
                                  env->gpr[xA1],
                                  env->gpr[xA2],
@@ -113,6 +116,16 @@
 
 void target_cpu_copy_regs(CPUArchState *env, struct target_pt_regs *regs)
 {
+    CPUState *cpu = ENV_GET_CPU(env);
+    TaskState *ts = cpu->opaque;
+    struct image_info *info = ts->info;
+
     env->pc = regs->sepc;
     env->gpr[xSP] = regs->sp;
+    env->elf_flags = info->elf_flags;
+
+    if ((env->misa & RVE) && !(env->elf_flags & EF_RISCV_RVE)) {
+        error_report("Incompatible ELF: RVE cpu requires RVE ABI binary");
+        exit(EXIT_FAILURE);
+    }
 }