Re: [PATCH v2 1/2] linux-user: add sched_getattr support

[Laurent Vivier]

Le 20/12/2021 à 08:21, Tonis Tiigi a écrit :

Signed-off-by: Tonis Tiigi <tonisti...@gmail.com>
---
  linux-user/syscall.c      | 72 +++++++++++++++++++++++++++++++++++++++
  linux-user/syscall_defs.h | 14 ++++++++
  2 files changed, 86 insertions(+)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index f1cfcc8104..a447ce1f92 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -339,6 +339,12 @@ _syscall3(int, sys_sched_getaffinity, pid_t, pid, unsigned 
int, len,
  #define __NR_sys_sched_setaffinity __NR_sched_setaffinity
  _syscall3(int, sys_sched_setaffinity, pid_t, pid, unsigned int, len,
            unsigned long *, user_mask_ptr);
+#define __NR_sys_sched_getattr __NR_sched_getattr
+_syscall4(int, sys_sched_getattr, pid_t, pid, struct target_sched_attr *, attr,
+          unsigned int, size, unsigned int, flags);
+#define __NR_sys_sched_setattr __NR_sched_setattr
+_syscall3(int, sys_sched_setattr, pid_t, pid, struct target_sched_attr *, attr,
+          unsigned int, flags);
  #define __NR_sys_getcpu __NR_getcpu
  _syscall3(int, sys_getcpu, unsigned *, cpu, unsigned *, node, void *, tcache);
  _syscall4(int, reboot, int, magic1, int, magic2, unsigned int, cmd,
@@ -10593,6 +10599,72 @@ static abi_long do_syscall1(void *cpu_env, int num, 
abi_long arg1,
          }
      case TARGET_NR_sched_getscheduler:
          return get_errno(sched_getscheduler(arg1));
+    case TARGET_NR_sched_getattr:
+        {
+            struct target_sched_attr *target_scha;
+            struct target_sched_attr scha;
+            if (arg2 == 0) {
+                return -TARGET_EINVAL;
+            }
+            if (arg3 > sizeof(scha)) {
+                arg3 = sizeof(scha);
+            }
+            ret = get_errno(sys_sched_getattr(arg1, &scha, arg3, arg4));
+            if (!is_error(ret)) {
+                target_scha = lock_user(VERIFY_WRITE, arg2, arg3, 0);
+                if (!target_scha) {
+                    return -TARGET_EFAULT;
+                }
+                target_scha->size = tswap32(scha.size);
+                target_scha->sched_policy = tswap32(scha.sched_policy);
+                target_scha->sched_flags = tswap64(scha.sched_policy);

wrong cut@paste: it's not sched_policy here.

+                target_scha->sched_nice = tswap32(scha.sched_nice);
+                target_scha->sched_priority = tswap32(scha.sched_priority);
+                target_scha->sched_runtime = tswap64(scha.sched_runtime);
+                target_scha->sched_deadline = tswap64(scha.sched_deadline);
+                target_scha->sched_period = tswap64(scha.sched_period);
+                if (scha.size > offsetof(struct target_sched_attr, 
sched_util_min)) {
+                    target_scha->sched_util_min = tswap32(scha.sched_util_min);
+                    target_scha->sched_util_max = tswap32(scha.sched_util_max);
+                }
+                unlock_user(target_scha, arg2, arg3);
+            }
+            return ret;
+        }
+    case TARGET_NR_sched_setattr:
+        {
+            struct target_sched_attr *target_scha;
+            struct target_sched_attr scha;
+            uint32_t *size;
+            if (arg2 == 0) {
+                return -TARGET_EINVAL;
+            }
+
+            if (!lock_user_struct(VERIFY_READ, size, arg2, 1)) {
+                return -TARGET_EFAULT;
+            }
+            unlock_user_struct(size, arg2, 0);
+            *size = tswap32(*size);

You should use get_user_u32() to do that.

But you should also check it's not 0 like in the kernel function 
sched_copy_attr():

        /* ABI compatibility quirk: */
        if (!size)
                size = SCHED_ATTR_SIZE_VER0;
        if (size < SCHED_ATTR_SIZE_VER0 || size > PAGE_SIZE)
                goto err_size;

(Note: I don't think we need to check for the PAGE_SIZE).


Thanks,
Laurent