From: Max Filippov <jcmvb...@gmail.com>
Entry opcode needs to check if moving to new register frame would cause
register window overflow. Entry used in function prologue never
overflows because preceding windowed call* opcode writes return address
to the target register window frame, causing overflow exceptions at the
point of call. But when a sequence of entry opcodes is used for register
window spilling there may not be a call or other opcode that would cause
window check between entries and they would not raise overflow exception
themselves resulting in data corruption.
Cc: qemu-sta...@nongnu.org
Signed-off-by: Max Filippov <jcmvb...@gmail.com>
(cherry picked from commit 1b3e71f8ee17ced609213d9b41758110f3c026e9)
Signed-off-by: Michael Roth <mdr...@linux.vnet.ibm.com>
---
target-xtensa/cpu.h | 6 ++++++
target-xtensa/op_helper.c | 6 ++++++
2 files changed, 12 insertions(+)
diff --git a/target-xtensa/cpu.h b/target-xtensa/cpu.h
index d797d26..6e4e2b2 100644
--- a/target-xtensa/cpu.h
+++ b/target-xtensa/cpu.h
@@ -471,6 +471,12 @@ static inline xtensa_tlb_entry
*xtensa_tlb_get_entry(CPUXtensaState *env,
env->itlb[wi] + ei;
}
+static inline uint32_t xtensa_replicate_windowstart(CPUXtensaState *env)
+{
+ return env->sregs[WINDOW_START] |
+ (env->sregs[WINDOW_START] << env->config->nareg / 4);
+}
+
/* MMU modes definitions */
#define MMU_MODE0_SUFFIX _ring0
#define MMU_MODE1_SUFFIX _ring1
diff --git a/target-xtensa/op_helper.c b/target-xtensa/op_helper.c
index dae1386..872e5a8 100644
--- a/target-xtensa/op_helper.c
+++ b/target-xtensa/op_helper.c
@@ -235,6 +235,12 @@ void HELPER(entry)(CPUXtensaState *env, uint32_t pc,
uint32_t s, uint32_t imm)
pc, env->sregs[PS]);
HELPER(exception_cause)(env, pc, ILLEGAL_INSTRUCTION_CAUSE);
} else {
+ uint32_t windowstart = xtensa_replicate_windowstart(env) >>
+ (env->sregs[WINDOW_BASE] + 1);
+
+ if (windowstart & ((1 << callinc) - 1)) {
+ HELPER(window_check)(env, pc, callinc);
+ }
env->regs[(callinc << 2) | (s & 3)] = env->regs[s] - (imm << 3);
rotate_window(env, callinc);
env->sregs[WINDOW_START] |=
--
1.9.1
