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target/arm: Add support for restoring v8M additional state context 

For v8M, exceptions from Secure to Non-Secure state will save
callee-saved registers to the exception frame as well as the
caller-saved registers. Add support for unstacking these
registers in exception exit when necessary.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 1506092407-26985-12-git-send-email-peter.maydell@linaro.org
This commit is contained in:
Peter Maydell 2017-10-06 16:46:48 +01:00
parent bfb2eb5278
commit 907bedb3f3
1 changed files with 30 additions and 0 deletions
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30
target/arm/helper.c
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@ -6463,6 +6463,36 @@ static void do_v7m_exception_exit(ARMCPU *cpu)
"for destination state is UNPREDICTABLE\n");
}
/* Do we need to pop callee-saved registers? */
if (return_to_secure &&
((excret & R_V7M_EXCRET_ES_MASK) == 0 ||
(excret & R_V7M_EXCRET_DCRS_MASK) == 0)) {
uint32_t expected_sig = 0xfefa125b;
uint32_t actual_sig = ldl_phys(cs->as, frameptr);
if (expected_sig != actual_sig) {
/* Take a SecureFault on the current stack */
env->v7m.sfsr |= R_V7M_SFSR_INVIS_MASK;
armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_SECURE, false);
v7m_exception_taken(cpu, excret);
qemu_log_mask(CPU_LOG_INT, "...taking SecureFault on existing "
"stackframe: failed exception return integrity "
"signature check\n");
return;
}
env->regs[4] = ldl_phys(cs->as, frameptr + 0x8);
env->regs[5] = ldl_phys(cs->as, frameptr + 0xc);
env->regs[6] = ldl_phys(cs->as, frameptr + 0x10);
env->regs[7] = ldl_phys(cs->as, frameptr + 0x14);
env->regs[8] = ldl_phys(cs->as, frameptr + 0x18);
env->regs[9] = ldl_phys(cs->as, frameptr + 0x1c);
env->regs[10] = ldl_phys(cs->as, frameptr + 0x20);
env->regs[11] = ldl_phys(cs->as, frameptr + 0x24);
frameptr += 0x28;
}
/* Pop registers. TODO: make these accesses use the correct
* attributes and address space (S/NS, priv/unpriv) and handle
* memory transaction failures.