Commit d9cdb2f1 authored by Wu Zhangjin's avatar Wu Zhangjin Committed by Ralf Baechle
Browse files

MIPS, Tracing: Substitute in_kernel_space() for in_module() 



The old in_module() may not work in some situations(e.g. when module &
kernel are in the same address space when CONFIG_MAPPED_KERNEL=y), The
in_kernel_space() is more generic and it is also easy to be implemented
via cloning the existing core_kernel_text(), so, replace the in_module()
with in_kernel_space().

Signed-off-by: default avatarWu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2005/


Signed-off-by: default avatarRalf Baechle <ralf@duck.linux-mips.net>
parent 9a620a55

arch/mips/kernel/ftrace.c

+27 −27
Original line number Diff line number Diff line
@@ -17,21 +17,7 @@ 
#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;

}

#include <asm-generic/sections.h>



#ifdef CONFIG_DYNAMIC_FTRACE
@@ -69,6 +55,20 @@ static inline void ftrace_dyn_arch_init_insns(void) 
#endif

}



/*

 * Check if the address is in kernel space

 *

 * Clone core_kernel_text() from kernel/extable.c, but doesn't call

 * init_kernel_text() for Ftrace doesn't trace functions in init sections.

 */

static inline int in_kernel_space(unsigned long ip)

{

	if (ip >= (unsigned long)_stext &&

	    ip <= (unsigned long)_etext)

		return 1;

	return 0;

}



static int ftrace_modify_code(unsigned long ip, unsigned int new_code)

{

	int faulted;
@@ -91,10 +91,16 @@ int ftrace_make_nop(struct module *mod, 
	unsigned long ip = rec->ip;



	/*

	 * We have compiled module with -mlong-calls, but compiled the kernel

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

	 * If ip is in kernel space, no long call, otherwise, long call is

	 * needed.

	 */

	if (in_module(ip)) {

	if (in_kernel_space(ip)) {

		/*

		 * move at, ra

		 * jal _mcount		--> nop

		 */

		new = INSN_NOP;

	} else {

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

		/*

		 * lui v1, hi_16bit_of_mcount        --> b 1f (0x10000005)
@@ -117,12 +123,6 @@ int ftrace_make_nop(struct module *mod, 
		 */

		new = INSN_B_1F_4;

#endif

	} else {

		/*

		 * move at, ra

		 * jal _mcount		--> nop

		 */

		new = INSN_NOP;

	}

	return ftrace_modify_code(ip, new);

}
@@ -132,8 +132,8 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 
	unsigned int new;

	unsigned long ip = rec->ip;



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

	new = in_module(ip) ? insn_lui_v1_hi16_mcount : insn_jal_ftrace_caller;

	new = in_kernel_space(ip) ? insn_jal_ftrace_caller :

		insn_lui_v1_hi16_mcount;



	return ftrace_modify_code(ip, new);

}
@@ -204,7 +204,7 @@ unsigned long ftrace_get_parent_addr(unsigned long self_addr, 
	 * instruction "lui v1, hi_16bit_of_mcount"(offset is 24), but for

	 * kernel, move after the instruction "move ra, at"(offset is 16)

	 */

	ip = self_addr - (in_module(self_addr) ? 24 : 16);

	ip = self_addr - (in_kernel_space(self_addr) ? 16 : 24);



	/*

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

CRA Git | Maintained and supported by SUSTech CRA and CCSE