/
common.c
322 lines (310 loc) · 7.12 KB
/
common.c
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#include "common.h"
void __attribute__((section(".fnptr"))) (*fn_ptr)(void);
void __attribute__((section(".aliasfnptr"))) (*alias_fn_ptr)(void);
void indirect(void *jmp_ptr) {
// HACK: relative jmp is 2 bytes (74 00 is "je foo\nfoo:")
// If you want these to all be taken, set rax=0x02
// otherwise there will be 16 not-taken branches
asm volatile(
"mov $2, %%rax\n"
"cmpb $0x02, %%al\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
// Do some indirect calls
"jmp call_get_rip\n"
"get_rip:\n"
"pop %%rax\n"
"push %%rax\n"
"ret\n"
"call_get_rip:\n"
"call get_rip\n"
"add (%%rcx), %%rax\n" // This will stall (assuming jmp_ptr is not in cache)
// len("add (rbx), rax") + len("add $9, rax") + len("jmpq *rax") => 9
"add $9, %%rax\n"
// 1
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 2
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 3
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 4
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 5
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 6
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 7
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 8
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 9
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 10
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 11
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 12
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 13
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 14
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 15
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 16
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 17
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 18
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 19
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 20
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 21
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 21
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 12
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 23
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 24
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 25
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 26
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 27
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 28
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 29
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 30
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 31
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 32
"jmpq *%%rax\n"
"nop\n"
:: "c"(jmp_ptr) : "rax");
// Do indirect jump
(*fn_ptr)();
}
void alias_indirect(void *jmp_ptr) {
// HACK: relative jmp is 2 bytes (74 00 is "je foo\nfoo:")
// If you want these to all be taken, set rax=0x02
// otherwise there will be 16 not-taken branches
asm volatile(
"mov $2, %%rax\n"
"cmpb $0x02, %%al\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
"je .+2\n"
// Do some indirect calls
"jmp call_get_rip_al\n"
"get_rip_al:\n"
"pop %%rax\n"
"push %%rax\n"
"ret\n"
"call_get_rip_al:\n"
"call get_rip_al\n"
"add (%%rcx), %%rax\n"
// len("add (rbx), rax") + len("add $9, rax") + len("jmpq *rax") => 9
"add $9, %%rax\n"
// 1
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 2
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 3
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 4
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 5
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 6
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 7
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 8
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 9
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 10
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 11
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 12
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 13
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 14
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 15
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 16
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 17
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 18
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 19
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 20
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 21
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 21
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 12
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 23
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 24
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 25
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 26
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 27
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 28
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 29
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 30
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 31
"jmpq *%%rax\n"
"add $6, %%rax\n"
// 32
"jmpq *%%rax\n"
"nop\n"
"end_indirect:"
:: "c"(jmp_ptr) : "rax");
// Do indirect jump
(*alias_fn_ptr)();
}