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https://github.com/cirosantilli/linux-kernel-module-cheat.git
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63 lines
1.3 KiB
ArmAsm
63 lines
1.3 KiB
ArmAsm
/* https://cirosantilli.com/linux-kernel-module-cheat#x86-jcc-instructions */
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#include <lkmc.h>
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LKMC_PROLOGUE
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/* JZ, JE */
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mov $1, %r12
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cmp $1, %r12
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LKMC_ASSERT(jz)
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cmp $2, %r12
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LKMC_ASSERT(jnz)
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/* JA, JB, JG, JL */
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/* 0x0 ==
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*
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* * 0 in 2's complement signed
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* * 0 in 2's complement unsigned
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*/
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mov $0, %al
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/* 0xFF ==
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*
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* * -1 in 2's complement signed
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* * 255 in 2's complement unsigned
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*/
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mov $0xFF, %bl
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/* Do the operation. */
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cmp %bl, %al
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/* We push and pop flags with PUSHF and POPF because
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* our assert function might change them. All comparisons
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* are done with the flags of the original cmp operation.
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*
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* We push twice to keep the stack aligned to 16 bits
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* when calling our C asset function.
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*/
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pushf
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pushf
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/* 0 < 255 */
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LKMC_ASSERT(jb)
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popf
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pushf
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/* !(0 > 255) */
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LKMC_ASSERT(jna)
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popf
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pushf
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/* !(0 < -1) */
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LKMC_ASSERT(jnl)
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popf
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pushf
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/* 0 > -1 */
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LKMC_ASSERT(jg)
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/* Restore stack. */
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add $16, %rsp
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LKMC_EPILOGUE
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