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c9f6e9977e
otherwise we will get for some user-space applications that use 'clone' with CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID end up hitting an assert in glibc manifested by: general protection ip:7f80720d364c sp:7fff98fd8a80 error:0 in libc-2.13.so[7f807209e000+180000] This is due to the nature of said operations which sets and clears the PID. "In the successful one I can see that the page table of the parent process has been updated successfully to use a different physical page, so the write of the tid on that page only affects the child... On the other hand, in the failed case, the write seems to happen before the copy of the original page is done, so both the parent and the child end up with the same value (because the parent copies the page after the write of the child tid has already happened)." (Roger's analysis). The nature of this is due to the Xen's commit of 51e2cac257ec8b4080d89f0855c498cbbd76a5e5 "x86/pvh: set only minimal cr0 and cr4 flags in order to use paging" the CR0_WP was removed so COW features of the Linux kernel were not operating properly. While doing that also update the rest of the CR0 flags to be inline with what a baremetal Linux kernel would set them to. In 'secondary_startup_64' (baremetal Linux) sets: X86_CR0_PE | X86_CR0_MP | X86_CR0_ET | X86_CR0_NE | X86_CR0_WP | X86_CR0_AM | X86_CR0_PG The hypervisor for HVM type guests (which PVH is a bit) sets: X86_CR0_PE | X86_CR0_ET | X86_CR0_TS For PVH it specifically sets: X86_CR0_PG Which means we need to set the rest: X86_CR0_MP | X86_CR0_NE | X86_CR0_WP | X86_CR0_AM to have full parity. Signed-off-by: Roger Pau Monne <roger.pau@citrix.com> Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> [v1: Took out the cr4 writes to be a seperate patch] [v2: 0-DAY kernel found xen_setup_gdt to be missing a static]
127 lines
3.4 KiB
C
127 lines
3.4 KiB
C
#ifndef XEN_OPS_H
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#define XEN_OPS_H
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#include <linux/init.h>
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#include <linux/clocksource.h>
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#include <linux/irqreturn.h>
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#include <xen/xen-ops.h>
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/* These are code, but not functions. Defined in entry.S */
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extern const char xen_hypervisor_callback[];
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extern const char xen_failsafe_callback[];
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extern void *xen_initial_gdt;
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struct trap_info;
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void xen_copy_trap_info(struct trap_info *traps);
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DECLARE_PER_CPU(struct vcpu_info, xen_vcpu_info);
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DECLARE_PER_CPU(unsigned long, xen_cr3);
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DECLARE_PER_CPU(unsigned long, xen_current_cr3);
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extern struct start_info *xen_start_info;
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extern struct shared_info xen_dummy_shared_info;
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extern struct shared_info *HYPERVISOR_shared_info;
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void xen_setup_mfn_list_list(void);
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void xen_setup_shared_info(void);
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void xen_build_mfn_list_list(void);
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void xen_setup_machphys_mapping(void);
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void xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn);
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void xen_reserve_top(void);
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extern unsigned long xen_max_p2m_pfn;
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void xen_set_pat(u64);
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char * __init xen_memory_setup(void);
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void __init xen_arch_setup(void);
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void xen_enable_sysenter(void);
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void xen_enable_syscall(void);
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void xen_vcpu_restore(void);
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void xen_callback_vector(void);
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void xen_hvm_init_shared_info(void);
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void xen_unplug_emulated_devices(void);
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void __init xen_build_dynamic_phys_to_machine(void);
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unsigned long __init xen_revector_p2m_tree(void);
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void xen_init_irq_ops(void);
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void xen_setup_timer(int cpu);
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void xen_setup_runstate_info(int cpu);
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void xen_teardown_timer(int cpu);
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cycle_t xen_clocksource_read(void);
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void xen_setup_cpu_clockevents(void);
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void __init xen_init_time_ops(void);
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void __init xen_hvm_init_time_ops(void);
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irqreturn_t xen_debug_interrupt(int irq, void *dev_id);
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bool xen_vcpu_stolen(int vcpu);
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void xen_setup_vcpu_info_placement(void);
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#ifdef CONFIG_SMP
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void xen_smp_init(void);
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void __init xen_hvm_smp_init(void);
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extern cpumask_var_t xen_cpu_initialized_map;
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#else
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static inline void xen_smp_init(void) {}
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static inline void xen_hvm_smp_init(void) {}
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#endif
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#ifdef CONFIG_PARAVIRT_SPINLOCKS
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void __init xen_init_spinlocks(void);
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void xen_init_lock_cpu(int cpu);
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void xen_uninit_lock_cpu(int cpu);
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#else
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static inline void xen_init_spinlocks(void)
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{
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}
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static inline void xen_init_lock_cpu(int cpu)
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{
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}
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static inline void xen_uninit_lock_cpu(int cpu)
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{
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}
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#endif
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struct dom0_vga_console_info;
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#ifdef CONFIG_XEN_DOM0
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void __init xen_init_vga(const struct dom0_vga_console_info *, size_t size);
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void __init xen_init_apic(void);
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#else
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static inline void __init xen_init_vga(const struct dom0_vga_console_info *info,
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size_t size)
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{
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}
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static inline void __init xen_init_apic(void)
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{
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}
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#endif
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/* Declare an asm function, along with symbols needed to make it
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inlineable */
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#define DECL_ASM(ret, name, ...) \
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__visible ret name(__VA_ARGS__); \
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extern char name##_end[] __visible; \
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extern char name##_reloc[] __visible
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DECL_ASM(void, xen_irq_enable_direct, void);
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DECL_ASM(void, xen_irq_disable_direct, void);
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DECL_ASM(unsigned long, xen_save_fl_direct, void);
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DECL_ASM(void, xen_restore_fl_direct, unsigned long);
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/* These are not functions, and cannot be called normally */
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__visible void xen_iret(void);
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__visible void xen_sysexit(void);
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__visible void xen_sysret32(void);
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__visible void xen_sysret64(void);
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__visible void xen_adjust_exception_frame(void);
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extern int xen_panic_handler_init(void);
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void xen_pvh_secondary_vcpu_init(int cpu);
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#endif /* XEN_OPS_H */
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