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target/arm: Implement SG instruction corner cases

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The common situation of the SG instruction is that it is
executed from S&NSC memory by a CPU in NS state. That case
is handled by v7m_handle_execute_nsc(). However the instruction
also has defined behaviour in a couple of other cases:
 * SG instruction in NS memory (behaves as a NOP)
 * SG in S memory but CPU already secure (clears IT bits and
   does nothing else)
 * SG instruction in v8M without Security Extension (NOP)

These can be implemented in translate.c.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 1507556919-24992-10-git-send-email-peter.maydell@linaro.org
This commit is contained in:
Peter Maydell 2017-10-09 14:48:39 +01:00
parent dcf14dfb70
commit 76eff04d16
1 changed files with 22 additions and 1 deletions
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23
target/arm/translate.c
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@ -9778,7 +9778,28 @@ static int disas_thumb2_insn(DisasContext *s, uint32_t insn)
* - load/store doubleword, load/store exclusive, ldacq/strel,
* table branch.
*/
if (insn & 0x01200000) {
if (insn == 0xe97fe97f && arm_dc_feature(s, ARM_FEATURE_M) &&
arm_dc_feature(s, ARM_FEATURE_V8)) {
/* 0b1110_1001_0111_1111_1110_1001_0111_111
* - SG (v8M only)
* The bulk of the behaviour for this instruction is implemented
* in v7m_handle_execute_nsc(), which deals with the insn when
* it is executed by a CPU in non-secure state from memory
* which is Secure & NonSecure-Callable.
* Here we only need to handle the remaining cases:
* * in NS memory (including the "security extension not
* implemented" case) : NOP
* * in S memory but CPU already secure (clear IT bits)
* We know that the attribute for the memory this insn is
* in must match the current CPU state, because otherwise
* get_phys_addr_pmsav8 would have generated an exception.
*/
if (s->v8m_secure) {
/* Like the IT insn, we don't need to generate any code */
s->condexec_cond = 0;
s->condexec_mask = 0;
}
} else if (insn & 0x01200000) {
/* 0b1110_1000_x11x_xxxx_xxxx_xxxx_xxxx_xxxx
* - load/store dual (post-indexed)
* 0b1111_1001_x10x_xxxx_xxxx_xxxx_xxxx_xxxx