9931033bbf
The vDSO (virtual dynamic shared object) is a small shared library that the kernel maps R/O into the address space of all Linux processes on image activation. The vDSO is a fully formed ELF image, shared by all processes with the same ABI, has no process private data. The primary purpose of the vDSO: - non-executable stack, signal trampolines not copied to the stack; - signal trampolines unwind, mandatory for the NPTL; - to avoid contex-switch overhead frequently used system calls can be implemented in the vDSO: for now gettimeofday, clock_gettime. The first two have been implemented, so add the implementation of system calls. System calls implemenation based on a native timekeeping code with some limitations: - ifunc can't be used, as vDSO r/o mapped to the process VA and rtld can't relocate symbols; - reading HPET memory is not implemented for now (TODO). In case on any error vDSO system calls fallback to the kernel system calls. For unimplemented vDSO system calls added prototypes which call corresponding kernel system call. Tested by: trasz (arm64) Differential revision: https://reviews.freebsd.org/D30900 MFC after: 2 weeks
158 lines
3.8 KiB
NASM
158 lines
3.8 KiB
NASM
/* $FreeBSD$ */
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#include "linux_assym.h" /* system definitions */
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#include <machine/asmacros.h> /* miscellaneous asm macros */
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#include <i386/linux/linux_syscall.h> /* system call numbers */
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#include "assym.inc"
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.data
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.globl linux_platform
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linux_platform:
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.asciz "i686"
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.text
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/*
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* To avoid excess stack frame the signal trampoline code emulates
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* the 'call' instruction.
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*/
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ENTRY(__kernel_sigreturn)
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movl %esp, %ebx /* preserve sigframe */
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call .getip0
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.getip0:
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popl %eax
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add $.startsigcode-.getip0, %eax /* ret address */
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push %eax
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jmp *LINUX_SIGF_HANDLER(%ebx)
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.startsigcode:
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popl %eax /* gcc unwind code need this */
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movl $LINUX_SYS_linux_sigreturn,%eax /* linux_sigreturn() */
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int $0x80 /* enter kernel with args */
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.endsigcode:
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0: jmp 0b
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ENTRY(__kernel_rt_sigreturn)
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leal LINUX_RT_SIGF_UC(%esp),%ebx /* linux ucp */
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leal LINUX_RT_SIGF_SC(%ebx),%ecx /* linux sigcontext */
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movl %esp, %edi
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call .getip1
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.getip1:
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popl %eax
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add $.startrtsigcode-.getip1, %eax /* ret address */
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push %eax
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jmp *LINUX_RT_SIGF_HANDLER(%edi)
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.startrtsigcode:
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movl $LINUX_SYS_linux_rt_sigreturn,%eax /* linux_rt_sigreturn() */
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int $0x80 /* enter kernel with args */
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.endrtsigcode:
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0: jmp 0b
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ENTRY(__kernel_vsyscall)
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.startvsyscall:
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int $0x80
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ret
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.endvsyscall:
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#if 0
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.section .note.Linux, "a",@note
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.long 2f - 1f /* namesz */
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.balign 4
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.long 4f - 3f /* descsz */
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.long 0
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1:
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.asciz "Linux"
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2:
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.balign 4
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3:
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.long LINUX_VERSION_CODE
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4:
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.balign 4
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.previous
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#endif
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#define do_cfa_expr(offset) \
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.byte 0x0f; /* DW_CFA_def_cfa_expression */ \
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.uleb128 11f-10f; /* length */ \
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10: .byte 0x74; /* DW_OP_breg4 */ \
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.sleb128 offset; /* offset */ \
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.byte 0x06; /* DW_OP_deref */ \
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11:
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/* CIE */
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.section .eh_frame,"a",@progbits
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.LSTARTFRAMEDLSI1:
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.long .LENDCIEDLSI1-.LSTARTCIEDLSI1
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.LSTARTCIEDLSI1:
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.long 0 /* CIE ID */
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.byte 1 /* Version number */
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.string "zRS" /* NULL-terminated
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* augmentation string
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*/
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.uleb128 1 /* Code alignment factor */
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.sleb128 -4 /* Data alignment factor */
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.byte 8 /* Return address
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* register column
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*/
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.uleb128 1 /* Augmentation value length */
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.byte 0x1b /* DW_EH_PE_pcrel|DW_EH_PE_sdata4. */
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.byte 0 /* DW_CFA_nop */
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.align 4
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.LENDCIEDLSI1:
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/* FDE */
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.long .LENDFDEDLSI1-.LSTARTFDEDLSI1 /* Length FDE */
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.LSTARTFDEDLSI1:
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.long .LSTARTFDEDLSI1-.LSTARTFRAMEDLSI1 /* CIE pointer */
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.long .startsigcode-. /* PC-relative start address */
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.long .endsigcode-.startsigcode
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.uleb128 0 /* Augmentation */
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do_cfa_expr(LINUX_SIGF_SC-8)
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.align 4
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.LENDFDEDLSI1:
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.long .LENDFDEDLSI2-.LSTARTFDEDLSI2 /* Length FDE */
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.LSTARTFDEDLSI2:
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.long .LSTARTFDEDLSI2-.LSTARTFRAMEDLSI1 /* CIE pointer */
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.long .startrtsigcode-. /* PC-relative start address */
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.long .endrtsigcode-.startrtsigcode
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.uleb128 0 /* Augmentation */
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do_cfa_expr(LINUX_RT_SIGF_SC-4+LINUX_SC_ESP)
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.align 4
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.LENDFDEDLSI2:
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.previous
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.section .eh_frame,"a",@progbits
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.LSTARTFRAMEDLSI2:
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.long .LENDCIEDLSI2-.LSTARTCIEDLSI2
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.LSTARTCIEDLSI2:
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.long 0 /* CIE ID */
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.byte 1 /* Version number */
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.string "zR" /* NULL-terminated
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* augmentation string
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*/
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.uleb128 1 /* Code alignment factor */
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.sleb128 -4 /* Data alignment factor */
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.byte 8 /* Return address register column */
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.uleb128 1 /* Augmentation value length */
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.byte 0x1b /* DW_EH_PE_pcrel|DW_EH_PE_sdata4. */
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.byte 0x0c /* DW_CFA_def_cfa */
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.uleb128 4
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.uleb128 4
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.byte 0x88 /* DW_CFA_offset, column 0x8 */
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.uleb128 1
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.align 4
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.LENDCIEDLSI2:
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.long .LENDFDEDLSI3-.LSTARTFDEDLSI3 /* Length FDE */
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.LSTARTFDEDLSI3:
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.long .LSTARTFDEDLSI3-.LSTARTFRAMEDLSI2 /* CIE pointer */
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.long .startvsyscall-. /* PC-relative start address */
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.long .endvsyscall-.startvsyscall
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.uleb128 0
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.align 4
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.LENDFDEDLSI3:
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.previous
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