[PULL 07/13] semihosting: Don't copy buffer after console_write()

Alex Bennée posted 13 patches 3 years, 6 months ago
Maintainers: Yonggang Luo <luoyonggang@gmail.com>, "Alex Bennée" <alex.bennee@linaro.org>, "Philippe Mathieu-Daudé" <f4bug@amsat.org>, Thomas Huth <thuth@redhat.com>, Wainer dos Santos Moschetta <wainersm@redhat.com>, Beraldo Leal <bleal@redhat.com>, Ed Maste <emaste@freebsd.org>, Li-Wen Hsu <lwhsu@freebsd.org>, Paolo Bonzini <pbonzini@redhat.com>, Eric Blake <eblake@redhat.com>, Markus Armbruster <armbru@redhat.com>, Richard Henderson <richard.henderson@linaro.org>, David Hildenbrand <david@redhat.com>
[PULL 07/13] semihosting: Don't copy buffer after console_write()
Posted by Alex Bennée 3 years, 6 months ago
From: Peter Maydell <peter.maydell@linaro.org>

The console_write() semihosting function outputs guest data from a
buffer; it doesn't update that buffer.  It therefore doesn't need to
pass a length value to unlock_user(), but can pass 0, meaning "do not
copy any data back to the guest memory".

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220719121110.225657-3-peter.maydell@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20220725140520.515340-8-alex.bennee@linaro.org>

diff --git a/semihosting/syscalls.c b/semihosting/syscalls.c
index 4847f66c02..508a0ad88c 100644
--- a/semihosting/syscalls.c
+++ b/semihosting/syscalls.c
@@ -627,7 +627,7 @@ static void console_write(CPUState *cs, gdb_syscall_complete_cb complete,
     }
     ret = qemu_semihosting_console_write(ptr, len);
     complete(cs, ret ? ret : -1, ret ? 0 : EIO);
-    unlock_user(ptr, buf, ret);
+    unlock_user(ptr, buf, 0);
 }
 
 static void console_fstat(CPUState *cs, gdb_syscall_complete_cb complete,
-- 
2.30.2