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61 lines
1.5 KiB
C++
61 lines
1.5 KiB
C++
#include <ucontext.h>
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#include <stddef.h>
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extern "C" void getcontext_light(ucontext_t *ctx);
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// clang's built-in asm cannot handle .set directives
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#if defined(__GNUC__) && !defined(__llvm__) && defined(__x86_64) && defined(_LP64)
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#define R(r) offsetof(ucontext_t, uc_mcontext.gregs[r])
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static __attribute__((used))
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void getcontext_tramp(ucontext_t *ctx) {
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__asm__ __volatile__(".set oRBX, %c0\n"
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".set oRBP, %c1\n"
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".set oR12, %c2\n"
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".set oR13, %c3\n"
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".set oR14, %c4\n"
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".set oR15, %c5\n"
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".set oRIP, %c6\n"
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".set oRSP, %c7\n"
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: :
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"p" (R(REG_RBX)),
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"p" (R(REG_RBP)),
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"p" (R(REG_R12)),
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"p" (R(REG_R13)),
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"p" (R(REG_R14)),
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"p" (R(REG_R15)),
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"p" (R(REG_RIP)),
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"p" (R(REG_RSP)));
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getcontext_light(ctx);
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}
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__asm__(".pushsection .text; .globl getcontext_light\n"
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".type getcontext_light, @function\n"
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"getcontext_light:\n"
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"\t.cfi_startproc\n"
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"\tmovq %rbx, oRBX(%rdi)\n"
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"\tmovq %rbp, oRBP(%rdi)\n"
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"\tmovq %r12, oR12(%rdi)\n"
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"\tmovq %r13, oR13(%rdi)\n"
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"\tmovq %r14, oR14(%rdi)\n"
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"\tmovq %r15, oR14(%rdi)\n"
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"\tmovq (%rsp), %rcx\n"
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"\tmovq %rcx, oRIP(%rdi)\n"
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"\tleaq 8(%rsp), %rcx\n" /* Exclude the return address. */
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"\tmovq %rcx, oRSP(%rdi)\n"
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"\tret\n"
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".cfi_endproc\n"
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".size getcontext_light, .-getcontext_light\n"
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".popsection\n"
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);
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#else
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extern "C" void getcontext_light(ucontext_t *ctx) {
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getcontext(ctx);
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}
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#endif
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