mirror of
https://github.com/dynup/kpatch
synced 2025-01-28 07:42:42 +00:00
53 lines
1.2 KiB
ArmAsm
53 lines
1.2 KiB
ArmAsm
#include <linux/linkage.h>
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#include <asm/calling.h>
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GLOBAL(kpatch_trampoline)
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pushq %rcx
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pushq %rdi
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callq kpatch_ftrace_hacks
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leaq kpatch_funcs, %r10
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/*
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* TODO: if preemption is possible then we'll need to think about how
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* to ensure atomic access to the array and how to ensure activeness
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* safety here. if preemption is enabled then we need to make sure the
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* IP isn't inside kpatch_trampoline for any task.
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*/
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/* TODO: save/restore flags? */
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/* find new function in func_list */
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popq %rdi
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loop:
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movq (%r10), %r9
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cmpq %r9, %rdi
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je found
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/*
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* Check for the rare case where we don't have a new function to call.
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* This can happen in the small window of time during patch module
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* insmod after it has called register_ftrace_function() but before it
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* has called stop_machine() to do the activeness safety check and the
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* array update. In this case we just return and let the old function
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* run.
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*/
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cmpq $0, %r9
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je bail
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addq $40, %r10 /* FIXME http://docs.blackfin.uclinux.org/doku.php?id=toolchain:gas:structs */
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jmp loop
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found:
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/* get new function address */
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movq 8(%r10), %r10
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/* tell ftrace to return to new function */
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popq %rax
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movq %r10, RIP(%rax)
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bail:
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retq
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