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Commit c9f84873 authored by Wu Zhangjin's avatar Wu Zhangjin Committed by Ralf Baechle
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MIPS: Tracing: Cleanup of address space checking 



This patch adds an inline function in_module() to check which space the
instruction pointer in, kernel space or module space.

Note:  This will not work when the kernel space and module space are the
same. If they are the same, we need to modify scripts/recordmcount.pl,
ftrace_make_nop/call() and the other related parts to ensure the
enabling/disabling of the calling site to _mcount is right for both
kernel and module.

[Ralf: It also is still incorrect for some 64-bit kernels.]

Signed-off-by: default avatarWu Zhangjin <wuzhangjin@gmail.com>
Cc: linux-mips <linux-mips@linux-mips.org>
Cc: David Daney <david.s.daney@gmail.com>
Patchwork: http://patchwork.linux-mips.org/patch/1232/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 68ccf752

arch/mips/kernel/ftrace.c

+19 −3
Original line number Diff line number Diff line
@@ -17,6 +17,22 @@ 
#include <asm/cacheflush.h>

#include <asm/uasm.h>



/*

 * If the Instruction Pointer is in module space (0xc0000000), return true;

 * otherwise, it is in kernel space (0x80000000), return false.

 *

 * FIXME: This will not work when the kernel space and module space are the

 * same. If they are the same, we need to modify scripts/recordmcount.pl,

 * ftrace_make_nop/call() and the other related parts to ensure the

 * enabling/disabling of the calling site to _mcount is right for both kernel

 * and module.

 */



static inline int in_module(unsigned long ip)

{

	return ip & 0x40000000;

}



#ifdef CONFIG_DYNAMIC_FTRACE



#define JAL 0x0c000000		/* jump & link: ip --> ra, jump to target */
@@ -78,7 +94,7 @@ int ftrace_make_nop(struct module *mod, 
	 * We have compiled module with -mlong-calls, but compiled the kernel

	 * without it, we need to cope with them respectively.

	 */

	if (ip & 0x40000000) {

	if (in_module(ip)) {

#if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT)

		/*

		 * lui v1, hi_16bit_of_mcount        --> b 1f (0x10000005)
@@ -117,7 +133,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 
	unsigned long ip = rec->ip;



	/* ip, module: 0xc0000000, kernel: 0x80000000 */

	new = (ip & 0x40000000) ? insn_lui_v1_hi16_mcount : insn_jal_ftrace_caller;

	new = in_module(ip) ? insn_lui_v1_hi16_mcount : insn_jal_ftrace_caller;



	return ftrace_modify_code(ip, new);

}
@@ -188,7 +204,7 @@ unsigned long ftrace_get_parent_addr(unsigned long self_addr, 
	 * instruction "lui v1, hi_16bit_of_mcount"(offset is 20), but for

	 * kernel, move to the instruction "move ra, at"(offset is 12)

	 */

	ip = self_addr - ((self_addr & 0x40000000) ? 20 : 12);

	ip = self_addr - (in_module(self_addr) ? 20 : 12);



	/*

	 * search the text until finding the non-store instruction or "s{d,w}