linux-user: Move syscall error detection into safe_syscall_base
The current api from safe_syscall_base() is to return -errno, which is
the interface provided by *some* linux kernel abis. The wrapper macro,
safe_syscall(), detects error, stores into errno, and returns -1, to
match the api of the system syscall().
For those kernel abis that do not return -errno natively, this leads
to double syscall error detection. E.g. Linux ppc64, which sets the
SO flag for error.
Simplify the usage from C by moving the error detection into assembly,
and usage from assembly by providing a C helper with which to set errno.
Reviewed-by: Warner Losh <imp@bsdimp.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
diff --git a/linux-user/safe-syscall.h b/linux-user/safe-syscall.h
index aaa9ffc..97837fa 100644
--- a/linux-user/safe-syscall.h
+++ b/linux-user/safe-syscall.h
@@ -127,21 +127,15 @@
#ifdef HAVE_SAFE_SYSCALL
/* The core part of this function is implemented in assembly */
extern long safe_syscall_base(int *pending, long number, ...);
+extern long safe_syscall_set_errno_tail(int value);
+
/* These are defined by the safe-syscall.inc.S file */
extern char safe_syscall_start[];
extern char safe_syscall_end[];
-#define safe_syscall(...) \
- ({ \
- long ret_; \
- int *psp_ = &((TaskState *)thread_cpu->opaque)->signal_pending; \
- ret_ = safe_syscall_base(psp_, __VA_ARGS__); \
- if (is_error(ret_)) { \
- errno = -ret_; \
- ret_ = -1; \
- } \
- ret_; \
- })
+#define safe_syscall(...) \
+ safe_syscall_base(&((TaskState *)thread_cpu->opaque)->signal_pending, \
+ __VA_ARGS__)
#else
