[PULL 06/10] target/i386: fix stack size when delivering real mode interrupts

Paolo Bonzini posted 10 patches 12 hours ago
Maintainers: Paolo Bonzini <pbonzini@redhat.com>, "Alex Bennée" <alex.bennee@linaro.org>, Thomas Huth <thuth@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>, "Marc-André Lureau" <marcandre.lureau@redhat.com>, "Daniel P. Berrangé" <berrange@redhat.com>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, John Snow <jsnow@redhat.com>, Cleber Rosa <crosa@redhat.com>, Cameron Esfahani <dirty@apple.com>, Roman Bolshakov <rbolshakov@ddn.com>, Phil Dennis-Jordan <phil@philjordan.eu>, Wei Liu <wei.liu@kernel.org>, Richard Henderson <richard.henderson@linaro.org>, Eduardo Habkost <eduardo@habkost.net>
[PULL 06/10] target/i386: fix stack size when delivering real mode interrupts
Posted by Paolo Bonzini 12 hours ago
The stack can be 32-bit even in real mode, and in this case
the stack pointer must be updated in its entirety rather than
just the bottom 16 bits.  The same is true of real mode IRET,
for which there was even a comment suggesting the right thing
to do.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1506
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target/i386/tcg/seg_helper.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/target/i386/tcg/seg_helper.c b/target/i386/tcg/seg_helper.c
index 667b1c38696..227336c4ef2 100644
--- a/target/i386/tcg/seg_helper.c
+++ b/target/i386/tcg/seg_helper.c
@@ -1161,7 +1161,7 @@ static void do_interrupt_real(CPUX86State *env, int intno, int is_int,
     sa.env = env;
     sa.ra = 0;
     sa.sp = env->regs[R_ESP];
-    sa.sp_mask = 0xffff;
+    sa.sp_mask = get_sp_mask(env->segs[R_SS].flags);
     sa.ss_base = env->segs[R_SS].base;
     sa.mmu_index = x86_mmu_index_pl(env, 0);
 
@@ -1964,7 +1964,7 @@ void helper_iret_real(CPUX86State *env, int shift)
     sa.env = env;
     sa.ra = GETPC();
     sa.mmu_index = x86_mmu_index_pl(env, 0);
-    sa.sp_mask = 0xffff; /* XXXX: use SS segment size? */
+    sa.sp_mask = get_sp_mask(env->segs[R_SS].flags);
     sa.sp = env->regs[R_ESP];
     sa.ss_base = env->segs[R_SS].base;
 
-- 
2.51.1