[Xen-devel] [PATCH 1/9] Revert "Use the extra stack for 16bit USB and PS2 keyboard/mouse commands."

["Luis R. Rodriguez" <mcgrof@xxxxxxxxxxxxxxxx>]

From: "Luis R. Rodriguez" <mcgrof@xxxxxxxx>

Upstream commit 12085439561f44107c7d3bea5a333a90ea987643

Kevin made this change upstream to seabios, this is needed for gcc5.
Mark Pryor reported the issue with gcc5 a while ago [0], he however
failed to follow up with an explanation as to what this does and why
this is needed.

        Revert "Use the extra stack for 16bit USB and PS2 keyboard/mouse 
commands."

        It's not valid to pass a pointer to a stack variable through the
        stack_hop() call (because the call changes the stack segment).  This
        bug was probably not noticed before because by default
        (CONFIG_ENTRY_EXTRASTACK) SeaBIOS uses the extra stack on all 16bit
        entry points, and the internal stack_hop() with that config option is
        effectively a no-op.

        This reverts commit d488a7683d90bf8fae7ceb8c3ad9e95fbbd92079.

        Signed-off-by: Kevin O'Connor <kevin@xxxxxxxxxxxx>

[0] http://lkml.kernel.org/r/1444332991-1706-1-git-send-email-pryorm09@xxxxxxxxx

Reported-by: Mark Pryor <pryorm09@xxxxxxxxx>
Cc: Kevin O'Connor <kevin@xxxxxxxxxxxx>
Cc: ian.campbell@xxxxxxxxxx
Cc: Jan Beulich <JBeulich@xxxxxxxx>
Cc: Mark Pryor <pryorm09@xxxxxxxxx>
Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxx>
---
 src/kbd.c   | 6 +++---
 src/mouse.c | 6 +++---
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/kbd.c b/src/kbd.c
index 33a95a398feb..fbcecc382eff 100644
--- a/src/kbd.c
+++ b/src/kbd.c
@@ -11,7 +11,7 @@
 #include "hw/ps2port.h" // ps2_kbd_command
 #include "hw/usb-hid.h" // usb_kbd_command
 #include "output.h" // debug_enter
-#include "stacks.h" // stack_hop
+#include "stacks.h" // yield
 #include "string.h" // memset
 #include "util.h" // kbd_init
 
@@ -117,8 +117,8 @@ static int
 kbd_command(int command, u8 *param)
 {
     if (usb_kbd_active())
-        return stack_hop(command, (u32)param, usb_kbd_command);
-    return stack_hop(command, (u32)param, ps2_kbd_command);
+        return usb_kbd_command(command, param);
+    return ps2_kbd_command(command, param);
 }
 
 // read keyboard input
diff --git a/src/mouse.c b/src/mouse.c
index 92ae9212c849..100255d60cfb 100644
--- a/src/mouse.c
+++ b/src/mouse.c
@@ -10,7 +10,7 @@
 #include "hw/ps2port.h" // ps2_mouse_command
 #include "hw/usb-hid.h" // usb_mouse_command
 #include "output.h" // dprintf
-#include "stacks.h" // stack_hop
+#include "stacks.h" // stack_hop_back
 #include "util.h" // mouse_init
 
 void
@@ -27,8 +27,8 @@ static int
 mouse_command(int command, u8 *param)
 {
     if (usb_mouse_active())
-        return stack_hop(command, (u32)param, usb_mouse_command);
-    return stack_hop(command, (u32)param, ps2_mouse_command);
+        return usb_mouse_command(command, param);
+    return ps2_mouse_command(command, param);
 }
 
 #define RET_SUCCESS      0x00
-- 
2.6.2


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