| Message ID | DS7PR12MB630905198DD8E69F6817544CAC4EA@DS7PR12MB6309.namprd12.prod.outlook.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | target/arm: trap DCC access in user mode emulation | expand |
On 6/2/23 14:43, Zhuojia Shen wrote: > Accessing EL0-accessible Debug Communication Channel (DCC) registers in > user mode emulation is currently enabled. However, it does not match > Linux behavior as Linux sets MDSCR_EL1.TDCC on startup to disable EL0 > access to DCC (see __cpu_setup() in arch/arm64/mm/proc.S). > > This patch fixes access_tdcc() to check MDSCR_EL1.TDCC for EL0 and sets > MDSCR_EL1.TDCC for user mode emulation to match Linux. > > Signed-off-by: Zhuojia Shen <chaosdefinition@hotmail.com> It would be nice to define the fields of MDSCR properly but either way, Reviewed-by: Richard Henderson <richard.henderson@linaro.org> r~
On Sat, 3 Jun 2023 at 05:52, Richard Henderson <richard.henderson@linaro.org> wrote: > > On 6/2/23 14:43, Zhuojia Shen wrote: > > Accessing EL0-accessible Debug Communication Channel (DCC) registers in > > user mode emulation is currently enabled. However, it does not match > > Linux behavior as Linux sets MDSCR_EL1.TDCC on startup to disable EL0 > > access to DCC (see __cpu_setup() in arch/arm64/mm/proc.S). > > > > This patch fixes access_tdcc() to check MDSCR_EL1.TDCC for EL0 and sets > > MDSCR_EL1.TDCC for user mode emulation to match Linux. > > > > Signed-off-by: Zhuojia Shen <chaosdefinition@hotmail.com> > > It would be nice to define the fields of MDSCR properly but either way, > > Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Applied to target-arm.next, thanks. -- PMM
diff --git a/target/arm/cpu.c b/target/arm/cpu.c index 5182ed0c91..4d5bb57f07 100644 --- a/target/arm/cpu.c +++ b/target/arm/cpu.c @@ -289,6 +289,8 @@ static void arm_cpu_reset_hold(Object *obj) * This is not yet exposed from the Linux kernel in any way. */ env->cp15.sctlr_el[1] |= SCTLR_TSCXT; + /* Disable access to Debug Communication Channel (DCC). */ + env->cp15.mdscr_el1 |= 1 << 12; #else /* Reset into the highest available EL */ if (arm_feature(env, ARM_FEATURE_EL3)) { diff --git a/target/arm/debug_helper.c b/target/arm/debug_helper.c index d41cc643b1..8362462a07 100644 --- a/target/arm/debug_helper.c +++ b/target/arm/debug_helper.c @@ -842,12 +842,14 @@ static CPAccessResult access_tda(CPUARMState *env, const ARMCPRegInfo *ri, * is implemented then these are controlled by MDCR_EL2.TDCC for * EL2 and MDCR_EL3.TDCC for EL3. They are also controlled by * the general debug access trap bits MDCR_EL2.TDA and MDCR_EL3.TDA. + * For EL0, they are also controlled by MDSCR_EL1.TDCC. */ static CPAccessResult access_tdcc(CPUARMState *env, const ARMCPRegInfo *ri, bool isread) { int el = arm_current_el(env); uint64_t mdcr_el2 = arm_mdcr_el2_eff(env); + bool mdscr_el1_tdcc = extract32(env->cp15.mdscr_el1, 12, 1); bool mdcr_el2_tda = (mdcr_el2 & MDCR_TDA) || (mdcr_el2 & MDCR_TDE) || (arm_hcr_el2_eff(env) & HCR_TGE); bool mdcr_el2_tdcc = cpu_isar_feature(aa64_fgt, env_archcpu(env)) && @@ -855,6 +857,9 @@ static CPAccessResult access_tdcc(CPUARMState *env, const ARMCPRegInfo *ri, bool mdcr_el3_tdcc = cpu_isar_feature(aa64_fgt, env_archcpu(env)) && (env->cp15.mdcr_el3 & MDCR_TDCC); + if (el < 1 && mdscr_el1_tdcc) { + return CP_ACCESS_TRAP; + } if (el < 2 && (mdcr_el2_tda || mdcr_el2_tdcc)) { return CP_ACCESS_TRAP_EL2; }
Accessing EL0-accessible Debug Communication Channel (DCC) registers in user mode emulation is currently enabled. However, it does not match Linux behavior as Linux sets MDSCR_EL1.TDCC on startup to disable EL0 access to DCC (see __cpu_setup() in arch/arm64/mm/proc.S). This patch fixes access_tdcc() to check MDSCR_EL1.TDCC for EL0 and sets MDSCR_EL1.TDCC for user mode emulation to match Linux. Signed-off-by: Zhuojia Shen <chaosdefinition@hotmail.com> --- target/arm/cpu.c | 2 ++ target/arm/debug_helper.c | 5 +++++ 2 files changed, 7 insertions(+)