arm64: Conditionally configure PTR_AUTH key of the kernel.
If the kernel is not compiled with CONFIG_ARM64_PTR_AUTH_KERNEL=y, then no PACI/AUTI instructions are expected while the kernel is running so the kernel's key will not be used. Write of a system registers is expensive therefore avoid if not required. Signed-off-by: Daniel Kiss <daniel.kiss@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/20210613092632.93591-3-daniel.kiss@arm.com Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Daniel Kiss
Will Deacon
Родитель
b27a9f4119
Коммит
d053e71ac8
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@ -1503,7 +1503,7 @@ config ARM64_PTR_AUTH
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not be selected.
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config ARM64_PTR_AUTH_KERNEL
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bool
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bool "Use pointer authentication for kernel"
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default y
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depends on ARM64_PTR_AUTH
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depends on (CC_HAS_SIGN_RETURN_ADDRESS || CC_HAS_BRANCH_PROT_PAC_RET) && AS_HAS_PAC
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@ -7,19 +7,7 @@
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#include <asm/cpufeature.h>
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#include <asm/sysreg.h>
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#ifdef CONFIG_ARM64_PTR_AUTH
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/*
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* thread.keys_user.ap* as offset exceeds the #imm offset range
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* so use the base value of ldp as thread.keys_user and offset as
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* thread.keys_user.ap*.
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*/
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.macro __ptrauth_keys_install_user tsk, tmp1, tmp2, tmp3
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mov \tmp1, #THREAD_KEYS_USER
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add \tmp1, \tsk, \tmp1
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ldp \tmp2, \tmp3, [\tmp1, #PTRAUTH_USER_KEY_APIA]
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msr_s SYS_APIAKEYLO_EL1, \tmp2
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msr_s SYS_APIAKEYHI_EL1, \tmp3
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.endm
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#ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
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.macro __ptrauth_keys_install_kernel_nosync tsk, tmp1, tmp2, tmp3
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mov \tmp1, #THREAD_KEYS_KERNEL
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@ -42,6 +30,33 @@ alternative_if ARM64_HAS_ADDRESS_AUTH
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alternative_else_nop_endif
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.endm
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#else /* CONFIG_ARM64_PTR_AUTH_KERNEL */
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.macro __ptrauth_keys_install_kernel_nosync tsk, tmp1, tmp2, tmp3
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.endm
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.macro ptrauth_keys_install_kernel_nosync tsk, tmp1, tmp2, tmp3
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.endm
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.macro ptrauth_keys_install_kernel tsk, tmp1, tmp2, tmp3
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.endm
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#endif /* CONFIG_ARM64_PTR_AUTH_KERNEL */
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#ifdef CONFIG_ARM64_PTR_AUTH
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/*
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* thread.keys_user.ap* as offset exceeds the #imm offset range
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* so use the base value of ldp as thread.keys_user and offset as
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* thread.keys_user.ap*.
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*/
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.macro __ptrauth_keys_install_user tsk, tmp1, tmp2, tmp3
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mov \tmp1, #THREAD_KEYS_USER
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add \tmp1, \tsk, \tmp1
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ldp \tmp2, \tmp3, [\tmp1, #PTRAUTH_USER_KEY_APIA]
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msr_s SYS_APIAKEYLO_EL1, \tmp2
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msr_s SYS_APIAKEYHI_EL1, \tmp3
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.endm
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.macro __ptrauth_keys_init_cpu tsk, tmp1, tmp2, tmp3
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mrs \tmp1, id_aa64isar1_el1
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ubfx \tmp1, \tmp1, #ID_AA64ISAR1_APA_SHIFT, #8
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@ -64,17 +79,11 @@ alternative_else_nop_endif
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.Lno_addr_auth\@:
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.endm
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#else /* CONFIG_ARM64_PTR_AUTH */
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#else /* !CONFIG_ARM64_PTR_AUTH */
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.macro ptrauth_keys_install_user tsk, tmp1, tmp2, tmp3
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.endm
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.macro ptrauth_keys_install_kernel_nosync tsk, tmp1, tmp2, tmp3
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.endm
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.macro ptrauth_keys_install_kernel tsk, tmp1, tmp2, tmp3
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.endm
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#endif /* CONFIG_ARM64_PTR_AUTH */
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#endif /* __ASM_ASM_POINTER_AUTH_H */
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@ -31,10 +31,6 @@ struct ptrauth_keys_user {
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struct ptrauth_key apga;
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};
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struct ptrauth_keys_kernel {
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struct ptrauth_key apia;
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};
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#define __ptrauth_key_install_nosync(k, v) \
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do { \
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struct ptrauth_key __pki_v = (v); \
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@ -42,6 +38,29 @@ do { \
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write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1); \
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} while (0)
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#ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
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struct ptrauth_keys_kernel {
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struct ptrauth_key apia;
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};
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static __always_inline void ptrauth_keys_init_kernel(struct ptrauth_keys_kernel *keys)
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{
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if (system_supports_address_auth())
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get_random_bytes(&keys->apia, sizeof(keys->apia));
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}
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static __always_inline void ptrauth_keys_switch_kernel(struct ptrauth_keys_kernel *keys)
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{
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if (!system_supports_address_auth())
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return;
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__ptrauth_key_install_nosync(APIA, keys->apia);
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isb();
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}
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#endif /* CONFIG_ARM64_PTR_AUTH_KERNEL */
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static inline void ptrauth_keys_install_user(struct ptrauth_keys_user *keys)
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{
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if (system_supports_address_auth()) {
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@ -69,21 +88,6 @@ static inline void ptrauth_keys_init_user(struct ptrauth_keys_user *keys)
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ptrauth_keys_install_user(keys);
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}
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static __always_inline void ptrauth_keys_init_kernel(struct ptrauth_keys_kernel *keys)
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{
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if (system_supports_address_auth())
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get_random_bytes(&keys->apia, sizeof(keys->apia));
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}
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static __always_inline void ptrauth_keys_switch_kernel(struct ptrauth_keys_kernel *keys)
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{
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if (!system_supports_address_auth())
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return;
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__ptrauth_key_install_nosync(APIA, keys->apia);
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isb();
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}
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extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
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extern int ptrauth_set_enabled_keys(struct task_struct *tsk, unsigned long keys,
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@ -121,11 +125,6 @@ static __always_inline void ptrauth_enable(void)
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#define ptrauth_thread_switch_user(tsk) \
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ptrauth_keys_install_user(&(tsk)->thread.keys_user)
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#define ptrauth_thread_init_kernel(tsk) \
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ptrauth_keys_init_kernel(&(tsk)->thread.keys_kernel)
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#define ptrauth_thread_switch_kernel(tsk) \
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ptrauth_keys_switch_kernel(&(tsk)->thread.keys_kernel)
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#else /* CONFIG_ARM64_PTR_AUTH */
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#define ptrauth_enable()
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#define ptrauth_prctl_reset_keys(tsk, arg) (-EINVAL)
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@ -134,11 +133,19 @@ static __always_inline void ptrauth_enable(void)
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#define ptrauth_strip_insn_pac(lr) (lr)
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#define ptrauth_suspend_exit()
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#define ptrauth_thread_init_user()
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#define ptrauth_thread_init_kernel(tsk)
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#define ptrauth_thread_switch_user(tsk)
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#define ptrauth_thread_switch_kernel(tsk)
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#endif /* CONFIG_ARM64_PTR_AUTH */
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#ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
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#define ptrauth_thread_init_kernel(tsk) \
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ptrauth_keys_init_kernel(&(tsk)->thread.keys_kernel)
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#define ptrauth_thread_switch_kernel(tsk) \
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ptrauth_keys_switch_kernel(&(tsk)->thread.keys_kernel)
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#else
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#define ptrauth_thread_init_kernel(tsk)
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#define ptrauth_thread_switch_kernel(tsk)
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#endif /* CONFIG_ARM64_PTR_AUTH_KERNEL */
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#define PR_PAC_ENABLED_KEYS_MASK \
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(PR_PAC_APIAKEY | PR_PAC_APIBKEY | PR_PAC_APDAKEY | PR_PAC_APDBKEY)
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@ -148,8 +148,10 @@ struct thread_struct {
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struct debug_info debug; /* debugging */
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#ifdef CONFIG_ARM64_PTR_AUTH
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struct ptrauth_keys_user keys_user;
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#ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
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struct ptrauth_keys_kernel keys_kernel;
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#endif
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#endif
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#ifdef CONFIG_ARM64_MTE
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u64 gcr_user_excl;
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#endif
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@ -155,7 +155,9 @@ int main(void)
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#endif
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#ifdef CONFIG_ARM64_PTR_AUTH
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DEFINE(PTRAUTH_USER_KEY_APIA, offsetof(struct ptrauth_keys_user, apia));
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#ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
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DEFINE(PTRAUTH_KERNEL_KEY_APIA, offsetof(struct ptrauth_keys_kernel, apia));
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#endif
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BLANK();
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#endif
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return 0;
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