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983df5f269
my_tramp[12]? are declared as global functions in C, but they are not
marked global in the inline assembly definition. This mismatch confuses
Clang's Control-Flow Integrity checking. Fix the definitions by adding
.globl.
Link: https://lkml.kernel.org/r/20201113183414.1446671-1-samitolvanen@google.com
Fixes: 9d907f1ae8 ("ftrace/samples: Add a sample module that implements modify_ftrace_direct()")
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
54 lines
1.2 KiB
C
54 lines
1.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/module.h>
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#include <linux/mm.h> /* for handle_mm_fault() */
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#include <linux/ftrace.h>
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void my_direct_func(struct vm_area_struct *vma,
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unsigned long address, unsigned int flags)
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{
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trace_printk("handle mm fault vma=%p address=%lx flags=%x\n",
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vma, address, flags);
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}
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extern void my_tramp(void *);
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asm (
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" .pushsection .text, \"ax\", @progbits\n"
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" .type my_tramp, @function\n"
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" .globl my_tramp\n"
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" my_tramp:"
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" pushq %rbp\n"
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" movq %rsp, %rbp\n"
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" pushq %rdi\n"
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" pushq %rsi\n"
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" pushq %rdx\n"
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" call my_direct_func\n"
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" popq %rdx\n"
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" popq %rsi\n"
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" popq %rdi\n"
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" leave\n"
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" ret\n"
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" .size my_tramp, .-my_tramp\n"
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" .popsection\n"
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);
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static int __init ftrace_direct_init(void)
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{
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return register_ftrace_direct((unsigned long)handle_mm_fault,
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(unsigned long)my_tramp);
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}
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static void __exit ftrace_direct_exit(void)
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{
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unregister_ftrace_direct((unsigned long)handle_mm_fault,
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(unsigned long)my_tramp);
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}
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module_init(ftrace_direct_init);
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module_exit(ftrace_direct_exit);
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MODULE_AUTHOR("Steven Rostedt");
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MODULE_DESCRIPTION("Another example use case of using register_ftrace_direct()");
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MODULE_LICENSE("GPL");
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