diff options
Diffstat (limited to 'arch/x86/xen/xen-asm_64.S')
| -rw-r--r-- | arch/x86/xen/xen-asm_64.S | 129 |
1 files changed, 127 insertions, 2 deletions
diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S index b147b49..4038cbf 100644 --- a/arch/x86/xen/xen-asm_64.S +++ b/arch/x86/xen/xen-asm_64.S @@ -15,6 +15,8 @@ #include <asm/asm-offsets.h> #include <asm/processor-flags.h> +#include <asm/errno.h> +#include <asm/segment.h> #include <xen/interface/xen.h> @@ -138,9 +140,132 @@ ENTRY(xen_adjust_exception_frame) mov 8+8(%rsp),%r11 ret $16 +hypercall_iret = hypercall_page + __HYPERVISOR_iret * 32 +/* + Xen64 iret frame: + + ss + rsp + rflags + cs + rip <-- standard iret frame + + flags + + rcx } + r11 }<-- pushed by hypercall page +rsp -> rax } + */ ENTRY(xen_iret) pushq $0 - jmp hypercall_page + __HYPERVISOR_iret * 32 +1: jmp hypercall_iret +ENDPATCH(xen_iret) +RELOC(xen_iret, 1b+1) +/* + sysexit is not used for 64-bit processes, so it's + only ever used to return to 32-bit compat userspace. + */ ENTRY(xen_sysexit) - ud2a + pushq $__USER32_DS + pushq %rcx + pushq $X86_EFLAGS_IF + pushq $__USER32_CS + pushq %rdx + + pushq $VGCF_in_syscall +1: jmp hypercall_iret +ENDPATCH(xen_sysexit) +RELOC(xen_sysexit, 1b+1) + +ENTRY(xen_sysret64) + /* We're already on the usermode stack at this point, but still + with the kernel gs, so we can easily switch back */ + movq %rsp, %gs:pda_oldrsp + movq %gs:pda_kernelstack,%rsp + + pushq $__USER_DS + pushq %gs:pda_oldrsp + pushq %r11 + pushq $__USER_CS + pushq %rcx + + pushq $VGCF_in_syscall +1: jmp hypercall_iret +ENDPATCH(xen_sysret64) +RELOC(xen_sysret64, 1b+1) + +ENTRY(xen_sysret32) + /* We're already on the usermode stack at this point, but still + with the kernel gs, so we can easily switch back */ + movq %rsp, %gs:pda_oldrsp + movq %gs:pda_kernelstack, %rsp + + pushq $__USER32_DS + pushq %gs:pda_oldrsp + pushq %r11 + pushq $__USER32_CS + pushq %rcx + + pushq $VGCF_in_syscall +1: jmp hypercall_iret +ENDPATCH(xen_sysret32) +RELOC(xen_sysret32, 1b+1) + +/* + Xen handles syscall callbacks much like ordinary exceptions, + which means we have: + - kernel gs + - kernel rsp + - an iret-like stack frame on the stack (including rcx and r11): + ss + rsp + rflags + cs + rip + r11 + rsp-> rcx + + In all the entrypoints, we undo all that to make it look + like a CPU-generated syscall/sysenter and jump to the normal + entrypoint. + */ + +.macro undo_xen_syscall + mov 0*8(%rsp),%rcx + mov 1*8(%rsp),%r11 + mov 5*8(%rsp),%rsp +.endm + +/* Normal 64-bit system call target */ +ENTRY(xen_syscall_target) + undo_xen_syscall + jmp system_call_after_swapgs +ENDPROC(xen_syscall_target) + +#ifdef CONFIG_IA32_EMULATION + +/* 32-bit compat syscall target */ +ENTRY(xen_syscall32_target) + undo_xen_syscall + jmp ia32_cstar_target +ENDPROC(xen_syscall32_target) + +/* 32-bit compat sysenter target */ +ENTRY(xen_sysenter_target) + undo_xen_syscall + jmp ia32_sysenter_target +ENDPROC(xen_sysenter_target) + +#else /* !CONFIG_IA32_EMULATION */ + +ENTRY(xen_syscall32_target) +ENTRY(xen_sysenter_target) + lea 16(%rsp), %rsp /* strip %rcx,%r11 */ + mov $-ENOSYS, %rax + pushq $VGCF_in_syscall + jmp hypercall_iret +ENDPROC(xen_syscall32_target) +ENDPROC(xen_sysenter_target) + +#endif /* CONFIG_IA32_EMULATION */ |
