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target/arm: Recalculate hflags correctly after writes to CONTROL 

A write to the CONTROL register can change our current EL (by
writing to the nPRIV bit). That means that we can't assume
that s->current_el is still valid in trans_MSR_v7m() when
we try to rebuild the hflags.

Add a new helper rebuild_hflags_m32_newel() which, like the
existing rebuild_hflags_a32_newel(), recalculates the current
EL from scratch, and use it in trans_MSR_v7m().

This fixes an assertion about an hflags mismatch when the
guest changes privilege by writing to CONTROL.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200303174950.3298-4-peter.maydell@linaro.org
This commit is contained in:
Peter Maydell 2020-03-03 17:49:49 +00:00
parent 0ea9e6583b
commit 19717e9b44
3 changed files with 16 additions and 4 deletions
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12
target/arm/helper.c
View File

@ -12468,6 +12468,18 @@ void arm_rebuild_hflags(CPUARMState *env)
env->hflags = rebuild_hflags_internal(env);
}
/*
* If we have triggered a EL state change we can't rely on the
* translator having passed it to us, we need to recompute.
*/
void HELPER(rebuild_hflags_m32_newel)(CPUARMState *env)
{
int el = arm_current_el(env);
int fp_el = fp_exception_el(env, el);
ARMMMUIdx mmu_idx = arm_mmu_idx_el(env, el);
env->hflags = rebuild_hflags_m32(env, fp_el, mmu_idx);
}
void HELPER(rebuild_hflags_m32)(CPUARMState *env, int el)
{
int fp_el = fp_exception_el(env, el);

1
target/arm/helper.h
View File

@ -90,6 +90,7 @@ DEF_HELPER_4(msr_banked, void, env, i32, i32, i32)
DEF_HELPER_2(get_user_reg, i32, env, i32)
DEF_HELPER_3(set_user_reg, void, env, i32, i32)
DEF_HELPER_FLAGS_1(rebuild_hflags_m32_newel, TCG_CALL_NO_RWG, void, env)
DEF_HELPER_FLAGS_2(rebuild_hflags_m32, TCG_CALL_NO_RWG, void, env, int)
DEF_HELPER_FLAGS_1(rebuild_hflags_a32_newel, TCG_CALL_NO_RWG, void, env)
DEF_HELPER_FLAGS_2(rebuild_hflags_a32, TCG_CALL_NO_RWG, void, env, int)

7
target/arm/translate.c
View File

@ -8551,7 +8551,7 @@ static bool trans_MRS_v7m(DisasContext *s, arg_MRS_v7m *a)
static bool trans_MSR_v7m(DisasContext *s, arg_MSR_v7m *a)
{
TCGv_i32 addr, reg, el;
TCGv_i32 addr, reg;
if (!arm_dc_feature(s, ARM_FEATURE_M)) {
return false;
@ -8561,9 +8561,8 @@ static bool trans_MSR_v7m(DisasContext *s, arg_MSR_v7m *a)
gen_helper_v7m_msr(cpu_env, addr, reg);
tcg_temp_free_i32(addr);
tcg_temp_free_i32(reg);
el = tcg_const_i32(s->current_el);
gen_helper_rebuild_hflags_m32(cpu_env, el);
tcg_temp_free_i32(el);
/* If we wrote to CONTROL, the EL might have changed */
gen_helper_rebuild_hflags_m32_newel(cpu_env);
gen_lookup_tb(s);
return true;
}