mirror of
https://github.com/cirosantilli/linux-kernel-module-cheat.git
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a90271c6af
Split userland/arch/<arch>/c/ into inline_asm and intrinsics, and move programs that don't match either up.
43 lines
1.1 KiB
C
43 lines
1.1 KiB
C
/* Like hello.c trying to do it without named register variables.
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* The code is more complicated, and I was not able to get as efficient,
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* so better just stick to named register variables.
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*
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* https://github.com/cirosantilli/linux-kernel-module-cheat#linux-system-calls
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*/
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#include <inttypes.h>
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void _start(void) {
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uint64_t exit_status;
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/* write */
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{
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char msg[] = "hello\n";
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uint64_t syscall_return;
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__asm__ (
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"mov x0, 1;" /* stdout */
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"mov x1, %[msg];"
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"mov x2, %[len];"
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"mov x8, 64;" /* syscall number */
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"svc 0;"
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"mov %[syscall_return], x0;"
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: [syscall_return] "=r" (syscall_return)
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: [msg] "p" (msg),
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[len] "i" (sizeof(msg))
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: "x0", "x1", "x2", "x8", "memory"
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);
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exit_status = (syscall_return != sizeof(msg));
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}
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/* exit */
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__asm__ (
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"mov x0, %[exit_status];"
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"mov x8, 93;" /* syscall number */
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"svc 0;"
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:
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: [exit_status] "r" (exit_status)
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: "x0", "x8"
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);
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}
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