From 1b3e71f8ee17ced609213d9b41758110f3c026e9 Mon Sep 17 00:00:00 2001 From: Max Filippov Date: Fri, 7 Nov 2014 21:11:07 +0300 Subject: [PATCH] target-xtensa: add missing window check for entry 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 --- 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 beb5486fc7..ac463f27fe 100644 --- a/target-xtensa/cpu.h +++ b/target-xtensa/cpu.h @@ -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 diff --git a/target-xtensa/op_helper.c b/target-xtensa/op_helper.c index dae13866ef..872e5a823b 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] |=