cregit-Linux how code gets into the kernel

Release 4.14 arch/sparc/kernel/ftrace.c

// SPDX-License-Identifier: GPL-2.0
#include <linux/spinlock.h>
#include <linux/hardirq.h>
#include <linux/ftrace.h>
#include <linux/percpu.h>
#include <linux/init.h>
#include <linux/list.h>
#include <trace/syscall.h>

#include <asm/ftrace.h>

#ifdef CONFIG_DYNAMIC_FTRACE

static const u32 ftrace_nop = 0x01000000;


static u32 ftrace_call_replace(unsigned long ip, unsigned long addr) { u32 call; s32 off; off = ((s32)addr - (s32)ip); call = 0x40000000 | ((u32)off >> 2); return call; }

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David S. Miller50100.00%2100.00%
Total50100.00%2100.00%


static int ftrace_modify_code(unsigned long ip, u32 old, u32 new) { u32 replaced; int faulted; __asm__ __volatile__( "1: cas [%[ip]], %[old], %[new]\n" " flush %[ip]\n" " mov 0, %[faulted]\n" "2:\n" " .section .fixup,#alloc,#execinstr\n" " .align 4\n" "3: sethi %%hi(2b), %[faulted]\n" " jmpl %[faulted] + %%lo(2b), %%g0\n" " mov 1, %[faulted]\n" " .previous\n" " .section __ex_table,\"a\"\n" " .align 4\n" " .word 1b, 3b\n" " .previous\n" : "=r" (replaced), [faulted] "=r" (faulted) : [new] "0" (new), [old] "r" (old), [ip] "r" (ip) : "memory"); if (replaced != old && replaced != new) faulted = 2; return faulted; }

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David S. Miller42100.00%2100.00%
Total42100.00%2100.00%


int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) { unsigned long ip = rec->ip; u32 old, new; old = ftrace_call_replace(ip, addr); new = ftrace_nop; return ftrace_modify_code(ip, old, new); }

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David S. Miller55100.00%1100.00%
Total55100.00%1100.00%


int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) { unsigned long ip = rec->ip; u32 old, new; old = ftrace_nop; new = ftrace_call_replace(ip, addr); return ftrace_modify_code(ip, old, new); }

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David S. Miller50100.00%1100.00%
Total50100.00%1100.00%


int ftrace_update_ftrace_func(ftrace_func_t func) { unsigned long ip = (unsigned long)(&ftrace_call); u32 old, new; old = *(u32 *) &ftrace_call; new = ftrace_call_replace(ip, (unsigned long)func); return ftrace_modify_code(ip, old, new); }

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David S. Miller59100.00%2100.00%
Total59100.00%2100.00%


int __init ftrace_dyn_arch_init(void) { return 0; }

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David S. Miller11100.00%1100.00%
Total11100.00%1100.00%

#endif #ifdef CONFIG_FUNCTION_GRAPH_TRACER #ifdef CONFIG_DYNAMIC_FTRACE extern void ftrace_graph_call(void);
int ftrace_enable_ftrace_graph_caller(void) { unsigned long ip = (unsigned long)(&ftrace_graph_call); u32 old, new; old = *(u32 *) &ftrace_graph_call; new = ftrace_call_replace(ip, (unsigned long) &ftrace_graph_caller); return ftrace_modify_code(ip, old, new); }

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David S. Miller59100.00%1100.00%
Total59100.00%1100.00%


int ftrace_disable_ftrace_graph_caller(void) { unsigned long ip = (unsigned long)(&ftrace_graph_call); u32 old, new; old = *(u32 *) &ftrace_graph_call; new = ftrace_call_replace(ip, (unsigned long) &ftrace_stub); return ftrace_modify_code(ip, old, new); }

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PersonTokensPropCommitsCommitProp
David S. Miller59100.00%1100.00%
Total59100.00%1100.00%

#endif /* !CONFIG_DYNAMIC_FTRACE */ /* * Hook the return address and push it in the stack of return addrs * in current thread info. */
unsigned long prepare_ftrace_return(unsigned long parent, unsigned long self_addr, unsigned long frame_pointer) { unsigned long return_hooker = (unsigned long) &return_to_handler; struct ftrace_graph_ent trace; if (unlikely(atomic_read(&current->tracing_graph_pause))) return parent + 8UL; trace.func = self_addr; trace.depth = current->curr_ret_stack + 1; /* Only trace if the calling function expects to */ if (!ftrace_graph_entry(&trace)) return parent + 8UL; if (ftrace_push_return_trace(parent, self_addr, &trace.depth, frame_pointer, NULL) == -EBUSY) return parent + 8UL; return return_hooker; }

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David S. Miller7870.27%133.33%
Liam R. Howlett3127.93%133.33%
Josh Poimboeuf21.80%133.33%
Total111100.00%3100.00%

#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

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David S. Miller51693.31%450.00%
Liam R. Howlett315.61%112.50%
Abhishek Sagar30.54%112.50%
Josh Poimboeuf20.36%112.50%
Greg Kroah-Hartman10.18%112.50%
Total553100.00%8100.00%
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