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https://github.com/cirosantilli/linux-kernel-module-cheat.git
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46 lines
1.2 KiB
ArmAsm
46 lines
1.2 KiB
ArmAsm
/* https://cirosantilli.com/linux-kernel-module-cheat#x86-push-and-pop-instructions */
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#include <lkmc.h>
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LKMC_PROLOGUE
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/* register hello world. */
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mov %rsp, %r12
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mov $0x123456789ABCDEF0, %rax
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push %rax
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/* Save the stack delta. */
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sub %rsp, %r12
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/* Save the stack value. */
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mov (%rsp), %r13
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/* Restore the stack and save its value to R14. */
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pop %r14
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/* The stack still goes down by 8 even though we pushed a 4-byte immediate. */
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LKMC_ASSERT_EQ(%r12, $8)
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LKMC_ASSERT_EQ(%r13, $0x123456789ABCDEF0)
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LKMC_ASSERT_EQ(%r14, $0x123456789ABCDEF0)
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/* Immediate. Can only push up to 4 byte immediates. */
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mov %rsp, %r12
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push $0x12345678
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sub %rsp, %r12
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mov (%rsp), %r13
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pop %r14
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/* The stack still goes down by 8 even though we pushed a 4-byte immediate. */
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LKMC_ASSERT_EQ(%r12, $8)
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LKMC_ASSERT_EQ(%r13, $0x12345678)
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LKMC_ASSERT_EQ(%r14, $0x12345678)
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/* Word example. */
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mov %rsp, %r12
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mov $0x1234, %ax
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push %ax
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sub %rsp, %r12
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mov $0, %r13
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mov (%rsp), %r13w
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mov $0, %r14
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pop %r14w
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/* The stack was decremented only by 2 as expected. */
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LKMC_ASSERT_EQ(%r12, $2)
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LKMC_ASSERT_EQ(%r13, $0x1234)
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LKMC_ASSERT_EQ(%r14, $0x1234)
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LKMC_EPILOGUE
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