HI Mark,
On 2020-05-19 11:44, Mark Rutland wrote:
On Wed, Apr 22, 2020 at 01:00:50PM +0100, Marc Zyngier wrote:
We currently assume that an exception is delivered to EL1, always.
Once we emulate EL2, this no longer will be the case. To prepare
for this, add a target_mode parameter.
While we're at it, merge the computing of the target PC and PSTATE in
a single function that updates both PC and CPSR after saving their
previous values in the corresponding ELR/SPSR. This ensures that they
are updated in the correct order (a pretty common source of bugs...).
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
arch/arm64/kvm/inject_fault.c | 75
++++++++++++++++++-----------------
1 file changed, 38 insertions(+), 37 deletions(-)
diff --git a/arch/arm64/kvm/inject_fault.c
b/arch/arm64/kvm/inject_fault.c
index d3ebf8bca4b89..3dbcbc839b9c3 100644
--- a/arch/arm64/kvm/inject_fault.c
+++ b/arch/arm64/kvm/inject_fault.c
@@ -26,28 +26,12 @@ enum exception_type {
except_type_serror = 0x180,
};
-static u64 get_except_vector(struct kvm_vcpu *vcpu, enum
exception_type type)
-{
- u64 exc_offset;
-
- switch (*vcpu_cpsr(vcpu) & (PSR_MODE_MASK | PSR_MODE32_BIT)) {
- case PSR_MODE_EL1t:
- exc_offset = CURRENT_EL_SP_EL0_VECTOR;
- break;
- case PSR_MODE_EL1h:
- exc_offset = CURRENT_EL_SP_ELx_VECTOR;
- break;
- case PSR_MODE_EL0t:
- exc_offset = LOWER_EL_AArch64_VECTOR;
- break;
- default:
- exc_offset = LOWER_EL_AArch32_VECTOR;
- }
-
- return vcpu_read_sys_reg(vcpu, VBAR_EL1) + exc_offset + type;
-}
-
/*
+ * This performs the exception entry at a given EL (@target_mode),
stashing PC
+ * and PSTATE into ELR and SPSR respectively, and compute the new
PC/PSTATE.
+ * The EL passed to this function *must* be a non-secure, privileged
mode with
+ * bit 0 being set (PSTATE.SP == 1).
+ *
* When an exception is taken, most PSTATE fields are left unchanged
in the
* handler. However, some are explicitly overridden (e.g. M[4:0]).
Luckily all
* of the inherited bits have the same position in the
AArch64/AArch32 SPSR_ELx
@@ -59,10 +43,35 @@ static u64 get_except_vector(struct kvm_vcpu
*vcpu, enum exception_type type)
* Here we manipulate the fields in order of the AArch64 SPSR_ELx
layout, from
* MSB to LSB.
*/
-static unsigned long get_except64_pstate(struct kvm_vcpu *vcpu)
+static void enter_exception(struct kvm_vcpu *vcpu, unsigned long
target_mode,
+ enum exception_type type)
Since this is all for an AArch64 target, could we keep `64` in the
name,
e.g enter_exception64? That'd mirror the callers below.
{
- unsigned long sctlr = vcpu_read_sys_reg(vcpu, SCTLR_EL1);
- unsigned long old, new;
+ unsigned long sctlr, vbar, old, new, mode;
+ u64 exc_offset;
+
+ mode = *vcpu_cpsr(vcpu) & (PSR_MODE_MASK | PSR_MODE32_BIT);
+
+ if (mode == target_mode)
+ exc_offset = CURRENT_EL_SP_ELx_VECTOR;
+ else if ((mode | 1) == target_mode)
+ exc_offset = CURRENT_EL_SP_EL0_VECTOR;
It would be nice if we could add a mnemonic for the `1` here, e.g.
PSR_MODE_SP0 or PSR_MODE_THREAD_BIT.
I've addressed both comments as follows:
diff --git a/arch/arm64/include/asm/ptrace.h
b/arch/arm64/include/asm/ptrace.h
index bf57308fcd63..953b6a1ce549 100644
--- a/arch/arm64/include/asm/ptrace.h
+++ b/arch/arm64/include/asm/ptrace.h
@@ -35,6 +35,7 @@
#define GIC_PRIO_PSR_I_SET (1 << 4)
/* Additional SPSR bits not exposed in the UABI */
+#define PSR_MODE_THREAD_BIT (1 << 0)
#define PSR_IL_BIT (1 << 20)
/* AArch32-specific ptrace requests */
diff --git a/arch/arm64/kvm/inject_fault.c
b/arch/arm64/kvm/inject_fault.c
index 3dbcbc839b9c..ebfdfc27b2bd 100644
--- a/arch/arm64/kvm/inject_fault.c
+++ b/arch/arm64/kvm/inject_fault.c
@@ -43,8 +43,8 @@ enum exception_type {
* Here we manipulate the fields in order of the AArch64 SPSR_ELx
layout, from
* MSB to LSB.
*/
-static void enter_exception(struct kvm_vcpu *vcpu, unsigned long
target_mode,
- enum exception_type type)
+static void enter_exception64(struct kvm_vcpu *vcpu, unsigned long
target_mode,
+ enum exception_type type)
{
unsigned long sctlr, vbar, old, new, mode;
u64 exc_offset;
@@ -53,7 +53,7 @@ static void enter_exception(struct kvm_vcpu *vcpu,
unsigned long target_mode,
if (mode == target_mode)
exc_offset = CURRENT_EL_SP_ELx_VECTOR;
- else if ((mode | 1) == target_mode)
+ else if ((mode | PSR_MODE_THREAD_BIT) == target_mode)
exc_offset = CURRENT_EL_SP_EL0_VECTOR;
else if (!(mode & PSR_MODE32_BIT))
exc_offset = LOWER_EL_AArch64_VECTOR;
@@ -126,7 +126,7 @@ static void inject_abt64(struct kvm_vcpu *vcpu, bool
is_iabt, unsigned long addr
bool is_aarch32 = vcpu_mode_is_32bit(vcpu);
u32 esr = 0;
- enter_exception(vcpu, PSR_MODE_EL1h, except_type_sync);
+ enter_exception64(vcpu, PSR_MODE_EL1h, except_type_sync);
vcpu_write_sys_reg(vcpu, addr, FAR_EL1);
@@ -156,7 +156,7 @@ static void inject_undef64(struct kvm_vcpu *vcpu)
{
u32 esr = (ESR_ELx_EC_UNKNOWN << ESR_ELx_EC_SHIFT);
- enter_exception(vcpu, PSR_MODE_EL1h, except_type_sync);
+ enter_exception64(vcpu, PSR_MODE_EL1h, except_type_sync);
/*
* Build an unknown exception, depending on the instruction
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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