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KVM: arm64: Rewrite system register accessors to read/write functions
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Currently we access the system registers array via the vcpu_sys_reg()
macro.  However, we are about to change the behavior to some times
modify the register file directly, so let's change this to two
primitives:

 * Accessor macros vcpu_write_sys_reg() and vcpu_read_sys_reg()
 * Direct array access macro __vcpu_sys_reg()

The accessor macros should be used in places where the code needs to
access the currently loaded VCPU's state as observed by the guest.  For
example, when trapping on cache related registers, a write to a system
register should go directly to the VCPU version of the register.

The direct array access macro can be used in places where the VCPU is
known to never be running (for example userspace access) or for
registers which are never context switched (for example all the PMU
system registers).

This rewrites all users of vcpu_sys_regs to one of the macros described
above.

No functional change.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Christoffer Dall <cdall@cs.columbia.edu>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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Christoffer Dall authored and Marc Zyngier committed Mar 19, 2018
1 parent 52f6c4f commit 8d404c4
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Showing 9 changed files with 101 additions and 76 deletions.
13 changes: 8 additions & 5 deletions arch/arm64/include/asm/kvm_emulate.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -290,23 +290,26 @@ static inline int kvm_vcpu_sys_get_rt(struct kvm_vcpu *vcpu)

static inline unsigned long kvm_vcpu_get_mpidr_aff(struct kvm_vcpu *vcpu)
{
return vcpu_sys_reg(vcpu, MPIDR_EL1) & MPIDR_HWID_BITMASK;
return vcpu_read_sys_reg(vcpu, MPIDR_EL1) & MPIDR_HWID_BITMASK;
}

static inline void kvm_vcpu_set_be(struct kvm_vcpu *vcpu)
{
if (vcpu_mode_is_32bit(vcpu))
if (vcpu_mode_is_32bit(vcpu)) {
*vcpu_cpsr(vcpu) |= COMPAT_PSR_E_BIT;
else
vcpu_sys_reg(vcpu, SCTLR_EL1) |= (1 << 25);
} else {
u64 sctlr = vcpu_read_sys_reg(vcpu, SCTLR_EL1);
sctlr |= (1 << 25);
vcpu_write_sys_reg(vcpu, SCTLR_EL1, sctlr);
}
}

static inline bool kvm_vcpu_is_be(struct kvm_vcpu *vcpu)
{
if (vcpu_mode_is_32bit(vcpu))
return !!(*vcpu_cpsr(vcpu) & COMPAT_PSR_E_BIT);

return !!(vcpu_sys_reg(vcpu, SCTLR_EL1) & (1 << 25));
return !!(vcpu_read_sys_reg(vcpu, SCTLR_EL1) & (1 << 25));
}

static inline unsigned long vcpu_data_guest_to_host(struct kvm_vcpu *vcpu,
Expand Down
13 changes: 12 additions & 1 deletion arch/arm64/include/asm/kvm_host.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -287,7 +287,18 @@ struct kvm_vcpu_arch {
};

#define vcpu_gp_regs(v) (&(v)->arch.ctxt.gp_regs)
#define vcpu_sys_reg(v,r) ((v)->arch.ctxt.sys_regs[(r)])

/*
* Only use __vcpu_sys_reg if you know you want the memory backed version of a
* register, and not the one most recently accessed by a running VCPU. For
* example, for userspace access or for system registers that are never context
* switched, but only emulated.
*/
#define __vcpu_sys_reg(v,r) ((v)->arch.ctxt.sys_regs[(r)])

#define vcpu_read_sys_reg(v,r) __vcpu_sys_reg(v,r)
#define vcpu_write_sys_reg(v,n,r) do { __vcpu_sys_reg(v,r) = n; } while (0)

/*
* CP14 and CP15 live in the same array, as they are backed by the
* same system registers.
Expand Down
2 changes: 1 addition & 1 deletion arch/arm64/include/asm/kvm_mmu.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -249,7 +249,7 @@ struct kvm;

static inline bool vcpu_has_cache_enabled(struct kvm_vcpu *vcpu)
{
return (vcpu_sys_reg(vcpu, SCTLR_EL1) & 0b101) == 0b101;
return (vcpu_read_sys_reg(vcpu, SCTLR_EL1) & 0b101) == 0b101;
}

static inline void __clean_dcache_guest_page(kvm_pfn_t pfn, unsigned long size)
Expand Down
28 changes: 19 additions & 9 deletions arch/arm64/kvm/debug.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -46,18 +46,22 @@ static DEFINE_PER_CPU(u32, mdcr_el2);
*/
static void save_guest_debug_regs(struct kvm_vcpu *vcpu)
{
vcpu->arch.guest_debug_preserved.mdscr_el1 = vcpu_sys_reg(vcpu, MDSCR_EL1);
u64 val = vcpu_read_sys_reg(vcpu, MDSCR_EL1);

vcpu->arch.guest_debug_preserved.mdscr_el1 = val;

trace_kvm_arm_set_dreg32("Saved MDSCR_EL1",
vcpu->arch.guest_debug_preserved.mdscr_el1);
}

static void restore_guest_debug_regs(struct kvm_vcpu *vcpu)
{
vcpu_sys_reg(vcpu, MDSCR_EL1) = vcpu->arch.guest_debug_preserved.mdscr_el1;
u64 val = vcpu->arch.guest_debug_preserved.mdscr_el1;

vcpu_write_sys_reg(vcpu, val, MDSCR_EL1);

trace_kvm_arm_set_dreg32("Restored MDSCR_EL1",
vcpu_sys_reg(vcpu, MDSCR_EL1));
vcpu_read_sys_reg(vcpu, MDSCR_EL1));
}

/**
Expand Down Expand Up @@ -108,6 +112,7 @@ void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu)
void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
{
bool trap_debug = !(vcpu->arch.debug_flags & KVM_ARM64_DEBUG_DIRTY);
unsigned long mdscr;

trace_kvm_arm_setup_debug(vcpu, vcpu->guest_debug);

Expand Down Expand Up @@ -152,9 +157,13 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
*/
if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) {
*vcpu_cpsr(vcpu) |= DBG_SPSR_SS;
vcpu_sys_reg(vcpu, MDSCR_EL1) |= DBG_MDSCR_SS;
mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1);
mdscr |= DBG_MDSCR_SS;
vcpu_write_sys_reg(vcpu, mdscr, MDSCR_EL1);
} else {
vcpu_sys_reg(vcpu, MDSCR_EL1) &= ~DBG_MDSCR_SS;
mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1);
mdscr &= ~DBG_MDSCR_SS;
vcpu_write_sys_reg(vcpu, mdscr, MDSCR_EL1);
}

trace_kvm_arm_set_dreg32("SPSR_EL2", *vcpu_cpsr(vcpu));
Expand All @@ -170,7 +179,9 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
*/
if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW) {
/* Enable breakpoints/watchpoints */
vcpu_sys_reg(vcpu, MDSCR_EL1) |= DBG_MDSCR_MDE;
mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1);
mdscr |= DBG_MDSCR_MDE;
vcpu_write_sys_reg(vcpu, mdscr, MDSCR_EL1);

vcpu->arch.debug_ptr = &vcpu->arch.external_debug_state;
vcpu->arch.debug_flags |= KVM_ARM64_DEBUG_DIRTY;
Expand All @@ -194,12 +205,11 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
vcpu->arch.mdcr_el2 |= MDCR_EL2_TDA;

/* If KDE or MDE are set, perform a full save/restore cycle. */
if ((vcpu_sys_reg(vcpu, MDSCR_EL1) & DBG_MDSCR_KDE) ||
(vcpu_sys_reg(vcpu, MDSCR_EL1) & DBG_MDSCR_MDE))
if (vcpu_read_sys_reg(vcpu, MDSCR_EL1) & (DBG_MDSCR_KDE | DBG_MDSCR_MDE))
vcpu->arch.debug_flags |= KVM_ARM64_DEBUG_DIRTY;

trace_kvm_arm_set_dreg32("MDCR_EL2", vcpu->arch.mdcr_el2);
trace_kvm_arm_set_dreg32("MDSCR_EL1", vcpu_sys_reg(vcpu, MDSCR_EL1));
trace_kvm_arm_set_dreg32("MDSCR_EL1", vcpu_read_sys_reg(vcpu, MDSCR_EL1));
}

void kvm_arm_clear_debug(struct kvm_vcpu *vcpu)
Expand Down
8 changes: 4 additions & 4 deletions arch/arm64/kvm/inject_fault.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -58,7 +58,7 @@ static u64 get_except_vector(struct kvm_vcpu *vcpu, enum exception_type type)
exc_offset = LOWER_EL_AArch32_VECTOR;
}

return vcpu_sys_reg(vcpu, VBAR_EL1) + exc_offset + type;
return vcpu_read_sys_reg(vcpu, VBAR_EL1) + exc_offset + type;
}

static void inject_abt64(struct kvm_vcpu *vcpu, bool is_iabt, unsigned long addr)
Expand All @@ -73,7 +73,7 @@ static void inject_abt64(struct kvm_vcpu *vcpu, bool is_iabt, unsigned long addr
*vcpu_cpsr(vcpu) = PSTATE_FAULT_BITS_64;
*vcpu_spsr(vcpu) = cpsr;

vcpu_sys_reg(vcpu, FAR_EL1) = addr;
vcpu_write_sys_reg(vcpu, addr, FAR_EL1);

/*
* Build an {i,d}abort, depending on the level and the
Expand All @@ -94,7 +94,7 @@ static void inject_abt64(struct kvm_vcpu *vcpu, bool is_iabt, unsigned long addr
if (!is_iabt)
esr |= ESR_ELx_EC_DABT_LOW << ESR_ELx_EC_SHIFT;

vcpu_sys_reg(vcpu, ESR_EL1) = esr | ESR_ELx_FSC_EXTABT;
vcpu_write_sys_reg(vcpu, esr | ESR_ELx_FSC_EXTABT, ESR_EL1);
}

static void inject_undef64(struct kvm_vcpu *vcpu)
Expand All @@ -115,7 +115,7 @@ static void inject_undef64(struct kvm_vcpu *vcpu)
if (kvm_vcpu_trap_il_is32bit(vcpu))
esr |= ESR_ELx_IL;

vcpu_sys_reg(vcpu, ESR_EL1) = esr;
vcpu_write_sys_reg(vcpu, esr, ESR_EL1);
}

/**
Expand Down
69 changes: 35 additions & 34 deletions arch/arm64/kvm/sys_regs.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -133,14 +133,14 @@ static bool access_vm_reg(struct kvm_vcpu *vcpu,
if (!p->is_aarch32 || !p->is_32bit) {
val = p->regval;
} else {
val = vcpu_sys_reg(vcpu, reg);
val = vcpu_read_sys_reg(vcpu, reg);
if (r->reg % 2)
val = (p->regval << 32) | (u64)lower_32_bits(val);
else
val = ((u64)upper_32_bits(val) << 32) |
lower_32_bits(p->regval);
}
vcpu_sys_reg(vcpu, reg) = val;
vcpu_write_sys_reg(vcpu, val, reg);

kvm_toggle_cache(vcpu, was_enabled);
return true;
Expand Down Expand Up @@ -249,10 +249,10 @@ static bool trap_debug_regs(struct kvm_vcpu *vcpu,
const struct sys_reg_desc *r)
{
if (p->is_write) {
vcpu_sys_reg(vcpu, r->reg) = p->regval;
vcpu_write_sys_reg(vcpu, p->regval, r->reg);
vcpu->arch.debug_flags |= KVM_ARM64_DEBUG_DIRTY;
} else {
p->regval = vcpu_sys_reg(vcpu, r->reg);
p->regval = vcpu_read_sys_reg(vcpu, r->reg);
}

trace_trap_reg(__func__, r->reg, p->is_write, p->regval);
Expand Down Expand Up @@ -465,7 +465,8 @@ static void reset_wcr(struct kvm_vcpu *vcpu,

static void reset_amair_el1(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
{
vcpu_sys_reg(vcpu, AMAIR_EL1) = read_sysreg(amair_el1);
u64 amair = read_sysreg(amair_el1);
vcpu_write_sys_reg(vcpu, amair, AMAIR_EL1);
}

static void reset_mpidr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
Expand All @@ -482,7 +483,7 @@ static void reset_mpidr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
mpidr = (vcpu->vcpu_id & 0x0f) << MPIDR_LEVEL_SHIFT(0);
mpidr |= ((vcpu->vcpu_id >> 4) & 0xff) << MPIDR_LEVEL_SHIFT(1);
mpidr |= ((vcpu->vcpu_id >> 12) & 0xff) << MPIDR_LEVEL_SHIFT(2);
vcpu_sys_reg(vcpu, MPIDR_EL1) = (1ULL << 31) | mpidr;
vcpu_write_sys_reg(vcpu, (1ULL << 31) | mpidr, MPIDR_EL1);
}

static void reset_pmcr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
Expand All @@ -496,12 +497,12 @@ static void reset_pmcr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
*/
val = ((pmcr & ~ARMV8_PMU_PMCR_MASK)
| (ARMV8_PMU_PMCR_MASK & 0xdecafbad)) & (~ARMV8_PMU_PMCR_E);
vcpu_sys_reg(vcpu, PMCR_EL0) = val;
__vcpu_sys_reg(vcpu, PMCR_EL0) = val;
}

static bool check_pmu_access_disabled(struct kvm_vcpu *vcpu, u64 flags)
{
u64 reg = vcpu_sys_reg(vcpu, PMUSERENR_EL0);
u64 reg = __vcpu_sys_reg(vcpu, PMUSERENR_EL0);
bool enabled = (reg & flags) || vcpu_mode_priv(vcpu);

if (!enabled)
Expand Down Expand Up @@ -543,14 +544,14 @@ static bool access_pmcr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,

if (p->is_write) {
/* Only update writeable bits of PMCR */
val = vcpu_sys_reg(vcpu, PMCR_EL0);
val = __vcpu_sys_reg(vcpu, PMCR_EL0);
val &= ~ARMV8_PMU_PMCR_MASK;
val |= p->regval & ARMV8_PMU_PMCR_MASK;
vcpu_sys_reg(vcpu, PMCR_EL0) = val;
__vcpu_sys_reg(vcpu, PMCR_EL0) = val;
kvm_pmu_handle_pmcr(vcpu, val);
} else {
/* PMCR.P & PMCR.C are RAZ */
val = vcpu_sys_reg(vcpu, PMCR_EL0)
val = __vcpu_sys_reg(vcpu, PMCR_EL0)
& ~(ARMV8_PMU_PMCR_P | ARMV8_PMU_PMCR_C);
p->regval = val;
}
Expand All @@ -568,10 +569,10 @@ static bool access_pmselr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
return false;

if (p->is_write)
vcpu_sys_reg(vcpu, PMSELR_EL0) = p->regval;
__vcpu_sys_reg(vcpu, PMSELR_EL0) = p->regval;
else
/* return PMSELR.SEL field */
p->regval = vcpu_sys_reg(vcpu, PMSELR_EL0)
p->regval = __vcpu_sys_reg(vcpu, PMSELR_EL0)
& ARMV8_PMU_COUNTER_MASK;

return true;
Expand Down Expand Up @@ -604,7 +605,7 @@ static bool pmu_counter_idx_valid(struct kvm_vcpu *vcpu, u64 idx)
{
u64 pmcr, val;

pmcr = vcpu_sys_reg(vcpu, PMCR_EL0);
pmcr = __vcpu_sys_reg(vcpu, PMCR_EL0);
val = (pmcr >> ARMV8_PMU_PMCR_N_SHIFT) & ARMV8_PMU_PMCR_N_MASK;
if (idx >= val && idx != ARMV8_PMU_CYCLE_IDX) {
kvm_inject_undefined(vcpu);
Expand All @@ -629,7 +630,7 @@ static bool access_pmu_evcntr(struct kvm_vcpu *vcpu,
if (pmu_access_event_counter_el0_disabled(vcpu))
return false;

idx = vcpu_sys_reg(vcpu, PMSELR_EL0)
idx = __vcpu_sys_reg(vcpu, PMSELR_EL0)
& ARMV8_PMU_COUNTER_MASK;
} else if (r->Op2 == 0) {
/* PMCCNTR_EL0 */
Expand Down Expand Up @@ -684,7 +685,7 @@ static bool access_pmu_evtyper(struct kvm_vcpu *vcpu, struct sys_reg_params *p,

if (r->CRn == 9 && r->CRm == 13 && r->Op2 == 1) {
/* PMXEVTYPER_EL0 */
idx = vcpu_sys_reg(vcpu, PMSELR_EL0) & ARMV8_PMU_COUNTER_MASK;
idx = __vcpu_sys_reg(vcpu, PMSELR_EL0) & ARMV8_PMU_COUNTER_MASK;
reg = PMEVTYPER0_EL0 + idx;
} else if (r->CRn == 14 && (r->CRm & 12) == 12) {
idx = ((r->CRm & 3) << 3) | (r->Op2 & 7);
Expand All @@ -702,9 +703,9 @@ static bool access_pmu_evtyper(struct kvm_vcpu *vcpu, struct sys_reg_params *p,

if (p->is_write) {
kvm_pmu_set_counter_event_type(vcpu, p->regval, idx);
vcpu_sys_reg(vcpu, reg) = p->regval & ARMV8_PMU_EVTYPE_MASK;
__vcpu_sys_reg(vcpu, reg) = p->regval & ARMV8_PMU_EVTYPE_MASK;
} else {
p->regval = vcpu_sys_reg(vcpu, reg) & ARMV8_PMU_EVTYPE_MASK;
p->regval = __vcpu_sys_reg(vcpu, reg) & ARMV8_PMU_EVTYPE_MASK;
}

return true;
Expand All @@ -726,15 +727,15 @@ static bool access_pmcnten(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
val = p->regval & mask;
if (r->Op2 & 0x1) {
/* accessing PMCNTENSET_EL0 */
vcpu_sys_reg(vcpu, PMCNTENSET_EL0) |= val;
__vcpu_sys_reg(vcpu, PMCNTENSET_EL0) |= val;
kvm_pmu_enable_counter(vcpu, val);
} else {
/* accessing PMCNTENCLR_EL0 */
vcpu_sys_reg(vcpu, PMCNTENSET_EL0) &= ~val;
__vcpu_sys_reg(vcpu, PMCNTENSET_EL0) &= ~val;
kvm_pmu_disable_counter(vcpu, val);
}
} else {
p->regval = vcpu_sys_reg(vcpu, PMCNTENSET_EL0) & mask;
p->regval = __vcpu_sys_reg(vcpu, PMCNTENSET_EL0) & mask;
}

return true;
Expand All @@ -758,12 +759,12 @@ static bool access_pminten(struct kvm_vcpu *vcpu, struct sys_reg_params *p,

if (r->Op2 & 0x1)
/* accessing PMINTENSET_EL1 */
vcpu_sys_reg(vcpu, PMINTENSET_EL1) |= val;
__vcpu_sys_reg(vcpu, PMINTENSET_EL1) |= val;
else
/* accessing PMINTENCLR_EL1 */
vcpu_sys_reg(vcpu, PMINTENSET_EL1) &= ~val;
__vcpu_sys_reg(vcpu, PMINTENSET_EL1) &= ~val;
} else {
p->regval = vcpu_sys_reg(vcpu, PMINTENSET_EL1) & mask;
p->regval = __vcpu_sys_reg(vcpu, PMINTENSET_EL1) & mask;
}

return true;
Expand All @@ -783,12 +784,12 @@ static bool access_pmovs(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
if (p->is_write) {
if (r->CRm & 0x2)
/* accessing PMOVSSET_EL0 */
vcpu_sys_reg(vcpu, PMOVSSET_EL0) |= (p->regval & mask);
__vcpu_sys_reg(vcpu, PMOVSSET_EL0) |= (p->regval & mask);
else
/* accessing PMOVSCLR_EL0 */
vcpu_sys_reg(vcpu, PMOVSSET_EL0) &= ~(p->regval & mask);
__vcpu_sys_reg(vcpu, PMOVSSET_EL0) &= ~(p->regval & mask);
} else {
p->regval = vcpu_sys_reg(vcpu, PMOVSSET_EL0) & mask;
p->regval = __vcpu_sys_reg(vcpu, PMOVSSET_EL0) & mask;
}

return true;
Expand Down Expand Up @@ -825,10 +826,10 @@ static bool access_pmuserenr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
return false;
}

vcpu_sys_reg(vcpu, PMUSERENR_EL0) = p->regval
& ARMV8_PMU_USERENR_MASK;
__vcpu_sys_reg(vcpu, PMUSERENR_EL0) =
p->regval & ARMV8_PMU_USERENR_MASK;
} else {
p->regval = vcpu_sys_reg(vcpu, PMUSERENR_EL0)
p->regval = __vcpu_sys_reg(vcpu, PMUSERENR_EL0)
& ARMV8_PMU_USERENR_MASK;
}

Expand Down Expand Up @@ -2230,7 +2231,7 @@ int kvm_arm_sys_reg_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg
if (r->get_user)
return (r->get_user)(vcpu, r, reg, uaddr);

return reg_to_user(uaddr, &vcpu_sys_reg(vcpu, r->reg), reg->id);
return reg_to_user(uaddr, &__vcpu_sys_reg(vcpu, r->reg), reg->id);
}

int kvm_arm_sys_reg_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
Expand All @@ -2251,7 +2252,7 @@ int kvm_arm_sys_reg_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg
if (r->set_user)
return (r->set_user)(vcpu, r, reg, uaddr);

return reg_from_user(&vcpu_sys_reg(vcpu, r->reg), uaddr, reg->id);
return reg_from_user(&__vcpu_sys_reg(vcpu, r->reg), uaddr, reg->id);
}

static unsigned int num_demux_regs(void)
Expand Down Expand Up @@ -2457,6 +2458,6 @@ void kvm_reset_sys_regs(struct kvm_vcpu *vcpu)
reset_sys_reg_descs(vcpu, table, num);

for (num = 1; num < NR_SYS_REGS; num++)
if (vcpu_sys_reg(vcpu, num) == 0x4242424242424242)
panic("Didn't reset vcpu_sys_reg(%zi)", num);
if (__vcpu_sys_reg(vcpu, num) == 0x4242424242424242)
panic("Didn't reset __vcpu_sys_reg(%zi)", num);
}
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