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target-xtensa: add missing window check for entry

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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-stable@nongnu.org
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
This commit is contained in:
Max Filippov 2014-11-07 21:11:07 +03:00
parent 2d9177588b
commit 1b3e71f8ee
2 changed files with 12 additions and 0 deletions
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6
target-xtensa/cpu.h
View File

@ -472,6 +472,12 @@ 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

6
target-xtensa/op_helper.c
View File

@ -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] |=