[S390] cleanup ftrace backend functions (4cc9bed0) · Commits · e / devices / android_kernel_fairphone_FP5

arch/s390/include/asm/ftrace.h

+4 −7

Original line number	Diff line number	Diff line
		@@ -4,20 +4,17 @@
		#ifndef __ASSEMBLY__

		extern void _mcount(void);
		extern unsigned long ftrace_dyn_func;

		struct dyn_arch_ftrace { };

		#define MCOUNT_ADDR ((long)_mcount)

		#ifdef CONFIG_64BIT
		#define MCOUNT_OFFSET_RET 18
		#define MCOUNT_INSN_SIZE 24
		#define MCOUNT_OFFSET 14
		#else
		#define MCOUNT_OFFSET_RET 26
		#define MCOUNT_INSN_SIZE 30
		#define MCOUNT_INSN_SIZE 12
		#define MCOUNT_OFFSET 8
		#else
		#define MCOUNT_INSN_SIZE 20
		#define MCOUNT_OFFSET 4
		#endif

		static inline unsigned long ftrace_call_adjust(unsigned long addr)

arch/s390/kernel/ftrace.c

+117 −121

Original line number	Diff line number	Diff line
		@@ -4,7 +4,7 @@
		* Copyright IBM Corp. 2009
		*
		* Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>,
		*
		* Martin Schwidefsky <schwidefsky@de.ibm.com>
		*/

		#include <linux/hardirq.h>
		@@ -12,123 +12,126 @@
		#include <linux/ftrace.h>
		#include <linux/kernel.h>
		#include <linux/types.h>
		#include <linux/kprobes.h>
		#include <trace/syscall.h>
		#include <asm/asm-offsets.h>

		#ifdef CONFIG_64BIT
		#define MCOUNT_OFFSET_RET 12
		#else
		#define MCOUNT_OFFSET_RET 22
		#endif

		#ifdef CONFIG_DYNAMIC_FTRACE

		void ftrace_disable_code(void);
		void ftrace_disable_return(void);
		void ftrace_call_code(void);
		void ftrace_nop_code(void);

		#define FTRACE_INSN_SIZE 4
		void ftrace_enable_insn(void);

		#ifdef CONFIG_64BIT

		/*
		* The 64-bit mcount code looks like this:
		* stg %r14,8(%r15) # offset 0
		* > larl %r1,<&counter> # offset 6
		* > brasl %r14,_mcount # offset 12
		* lg %r14,8(%r15) # offset 18
		* Total length is 24 bytes. The middle two instructions of the mcount
		* block get overwritten by ftrace_make_nop / ftrace_make_call.
		* The 64-bit enabled ftrace code block looks like this:
		* stg %r14,8(%r15) # offset 0
		* > lg %r1,__LC_FTRACE_FUNC # offset 6
		* > lgr %r0,%r0 # offset 12
		* > basr %r14,%r1 # offset 16
		* lg %r14,8(%15) # offset 18
		* The return points of the mcount/ftrace function have the same offset 18.
		* The 64-bit disable ftrace code block looks like this:
		* stg %r14,8(%r15) # offset 0
		* > jg .+18 # offset 6
		* > lgr %r0,%r0 # offset 12
		* > basr %r14,%r1 # offset 16
		* lg %r14,8(%15) # offset 18
		* The jg instruction branches to offset 24 to skip as many instructions
		* as possible.
		*/
		asm(
		" .align 4\n"
		"ftrace_disable_code:\n"
		" j 0f\n"
		" .word 0x0024\n"
		" lg %r1,"__stringify(__LC_FTRACE_FUNC)"\n"
		" basr %r14,%r1\n"
		"ftrace_disable_return:\n"
		" lg %r14,8(15)\n"
		" jg 0f\n"
		" lgr %r0,%r0\n"
		"0:\n");

		asm(
		" basr %r14,%r1\n"
		"0:\n"
		" .align 4\n"
		"ftrace_nop_code:\n"
		" j .+"__stringify(MCOUNT_INSN_SIZE)"\n");
		"ftrace_enable_insn:\n"
		" lg %r1,"__stringify(__LC_FTRACE_FUNC)"\n");

		asm(
		" .align 4\n"
		"ftrace_call_code:\n"
		" stg %r14,8(%r15)\n");
		#define FTRACE_INSN_SIZE 6

		#else /* CONFIG_64BIT */

		/*
		* The 31-bit mcount code looks like this:
		* st %r14,4(%r15) # offset 0
		* > bras %r1,0f # offset 4
		* > .long _mcount # offset 8
		* > .long <&counter> # offset 12
		* > 0: l %r14,0(%r1) # offset 16
		* > l %r1,4(%r1) # offset 20
		* basr %r14,%r14 # offset 24
		* l %r14,4(%r15) # offset 26
		* Total length is 30 bytes. The twenty bytes starting from offset 4
		* to offset 24 get overwritten by ftrace_make_nop / ftrace_make_call.
		* The 31-bit enabled ftrace code block looks like this:
		* st %r14,4(%r15) # offset 0
		* > l %r14,__LC_FTRACE_FUNC # offset 4
		* > j 0f # offset 8
		* > .fill 12,1,0x07 # offset 12
		* 0: basr %r14,%r14 # offset 24
		* l %r14,4(%r14) # offset 26
		* The return points of the mcount/ftrace function have the same offset 26.
		* The 31-bit disabled ftrace code block looks like this:
		* st %r14,4(%r15) # offset 0
		* > j .+26 # offset 4
		* > j 0f # offset 8
		* > .fill 12,1,0x07 # offset 12
		* 0: basr %r14,%r14 # offset 24
		* l %r14,4(%r14) # offset 26
		* The j instruction branches to offset 30 to skip as many instructions
		* as possible.
		*/
		asm(
		" .align 4\n"
		"ftrace_disable_code:\n"
		" j 1f\n"
		" j 0f\n"
		" l %r1,"__stringify(__LC_FTRACE_FUNC)"\n"
		" basr %r14,%r1\n"
		"ftrace_disable_return:\n"
		" l %r14,4(%r15)\n"
		" j 0f\n"
		" bcr 0,%r7\n"
		" bcr 0,%r7\n"
		" bcr 0,%r7\n"
		" bcr 0,%r7\n"
		" bcr 0,%r7\n"
		" bcr 0,%r7\n"
		"0:\n");

		asm(
		" .fill 12,1,0x07\n"
		"0: basr %r14,%r14\n"
		"1:\n"
		" .align 4\n"
		"ftrace_nop_code:\n"
		" j .+"__stringify(MCOUNT_INSN_SIZE)"\n");
		"ftrace_enable_insn:\n"
		" l %r14,"__stringify(__LC_FTRACE_FUNC)"\n");

		asm(
		" .align 4\n"
		"ftrace_call_code:\n"
		" st %r14,4(%r15)\n");
		#define FTRACE_INSN_SIZE 4

		#endif /* CONFIG_64BIT */

		static int ftrace_modify_code(unsigned long ip,
		void *old_code, int old_size,
		void *new_code, int new_size)
		{
		unsigned char replaced[MCOUNT_INSN_SIZE];

		/*
		* Note: Due to modules code can disappear and change.
		* We need to protect against faulting as well as code
		* changing. We do this by using the probe_kernel_*
		* functions.
		* This however is just a simple sanity check.
		*/
		if (probe_kernel_read(replaced, (void *)ip, old_size))
		return -EFAULT;
		if (memcmp(replaced, old_code, old_size) != 0)
		return -EINVAL;
		if (probe_kernel_write((void *)ip, new_code, new_size))
		return -EPERM;
		return 0;
		}

		static int ftrace_make_initial_nop(struct module mod, struct dyn_ftrace rec,
		unsigned long addr)
		{
		return ftrace_modify_code(rec->ip,
		ftrace_call_code, FTRACE_INSN_SIZE,
		ftrace_disable_code, MCOUNT_INSN_SIZE);
		}

		int ftrace_make_nop(struct module mod, struct dyn_ftrace rec,
		unsigned long addr)
		{
		if (addr == MCOUNT_ADDR)
		return ftrace_make_initial_nop(mod, rec, addr);
		return ftrace_modify_code(rec->ip,
		ftrace_call_code, FTRACE_INSN_SIZE,
		ftrace_nop_code, FTRACE_INSN_SIZE);
		if (probe_kernel_write((void *) rec->ip, ftrace_disable_code,
		MCOUNT_INSN_SIZE))
		return -EPERM;
		return 0;
		}

		int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
		{
		return ftrace_modify_code(rec->ip,
		ftrace_nop_code, FTRACE_INSN_SIZE,
		ftrace_call_code, FTRACE_INSN_SIZE);
		if (probe_kernel_write((void *) rec->ip, ftrace_enable_insn,
		FTRACE_INSN_SIZE))
		return -EPERM;
		return 0;
		}

		int ftrace_update_ftrace_func(ftrace_func_t func)
		{
		ftrace_dyn_func = (unsigned long)func;
		return 0;
		}

		@@ -141,47 +144,12 @@ int __init ftrace_dyn_arch_init(void *data)
		#endif /* CONFIG_DYNAMIC_FTRACE */

		#ifdef CONFIG_FUNCTION_GRAPH_TRACER
		#ifdef CONFIG_DYNAMIC_FTRACE
		/*
		* Patch the kernel code at ftrace_graph_caller location:
		* The instruction there is branch relative on condition. The condition mask
		* is either all ones (always branch aka disable ftrace_graph_caller) or all
		* zeroes (nop aka enable ftrace_graph_caller).
		* Instruction format for brc is a7m4xxxx where m is the condition mask.
		*/
		int ftrace_enable_ftrace_graph_caller(void)
		{
		unsigned short opcode = 0xa704;

		return probe_kernel_write(ftrace_graph_caller, &opcode, sizeof(opcode));
		}

		int ftrace_disable_ftrace_graph_caller(void)
		{
		unsigned short opcode = 0xa7f4;

		return probe_kernel_write(ftrace_graph_caller, &opcode, sizeof(opcode));
		}

		static inline unsigned long ftrace_mcount_call_adjust(unsigned long addr)
		{
		return addr - (ftrace_disable_return - ftrace_disable_code);
		}

		#else /* CONFIG_DYNAMIC_FTRACE */

		static inline unsigned long ftrace_mcount_call_adjust(unsigned long addr)
		{
		return addr - MCOUNT_OFFSET_RET;
		}

		#endif /* CONFIG_DYNAMIC_FTRACE */

		/*
		* Hook the return address and push it in the stack of return addresses
		* in current thread info.
		*/
		unsigned long prepare_ftrace_return(unsigned long ip, unsigned long parent)
		unsigned long __kprobes prepare_ftrace_return(unsigned long parent,
		unsigned long ip)
		{
		struct ftrace_graph_ent trace;

		@@ -189,7 +157,7 @@ unsigned long prepare_ftrace_return(unsigned long ip, unsigned long parent)
		goto out;
		if (ftrace_push_return_trace(parent, ip, &trace.depth, 0) == -EBUSY)
		goto out;
		trace.func = ftrace_mcount_call_adjust(ip) & PSW_ADDR_INSN;
		trace.func = (ip & PSW_ADDR_INSN) - MCOUNT_OFFSET_RET;
		/* Only trace if the calling function expects to. */
		if (!ftrace_graph_entry(&trace)) {
		current->curr_ret_stack--;
		@@ -199,4 +167,32 @@ unsigned long prepare_ftrace_return(unsigned long ip, unsigned long parent)
		out:
		return parent;
		}

		#ifdef CONFIG_DYNAMIC_FTRACE
		/*
		* Patch the kernel code at ftrace_graph_caller location. The instruction
		* there is branch relative and save to prepare_ftrace_return. To disable
		* the call to prepare_ftrace_return we patch the bras offset to point
		* directly after the instructions. To enable the call we calculate
		* the original offset to prepare_ftrace_return and put it back.
		*/
		int ftrace_enable_ftrace_graph_caller(void)
		{
		unsigned short offset;

		offset = ((void *) prepare_ftrace_return -
		(void *) ftrace_graph_caller) / 2;
		return probe_kernel_write(ftrace_graph_caller + 2,
		&offset, sizeof(offset));
		}

		int ftrace_disable_ftrace_graph_caller(void)
		{
		static unsigned short offset = 0x0002;

		return probe_kernel_write(ftrace_graph_caller + 2,
		&offset, sizeof(offset));
		}

		#endif /* CONFIG_DYNAMIC_FTRACE */
		#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

arch/s390/kernel/mcount.S

+7 −23

Original line number	Diff line number	Diff line
		@@ -18,22 +18,12 @@ _mcount:
		#ifdef CONFIG_DYNAMIC_FTRACE
		br %r14

		.data
		.globl ftrace_dyn_func
		ftrace_dyn_func:
		.long ftrace_stub
		.previous

		.globl ftrace_caller
		ftrace_caller:
		#endif
		stm %r2,%r5,16(%r15)
		bras %r1,2f
		#ifdef CONFIG_DYNAMIC_FTRACE
		0: .long ftrace_dyn_func
		#else
		0: .long ftrace_trace_function
		#endif
		1: .long function_trace_stop
		2: l %r2,1b-0b(%r1)
		icm %r2,0xf,0(%r2)
		@@ -49,21 +39,15 @@ ftrace_caller:
		l %r14,0(%r14)
		basr %r14,%r14
		#ifdef CONFIG_FUNCTION_GRAPH_TRACER
		#ifdef CONFIG_DYNAMIC_FTRACE
		l %r2,100(%r15)
		l %r3,152(%r15)
		.globl ftrace_graph_caller
		ftrace_graph_caller:
		# This unconditional branch gets runtime patched. Change only if
		# you know what you are doing. See ftrace_enable_graph_caller().
		j 1f
		#endif
		bras %r1,0f
		.long prepare_ftrace_return
		0: l %r2,152(%r15)
		l %r4,0(%r1)
		l %r3,100(%r15)
		basr %r14,%r4
		st %r2,100(%r15)
		1:
		# The bras instruction gets runtime patched to call prepare_ftrace_return.
		# See ftrace_enable_ftrace_graph_caller. The patched instruction is:
		# bras %r14,prepare_ftrace_return
		bras %r14,0f
		0: st %r2,100(%r15)
		#endif
		ahi %r15,96
		l %r14,56(%r15)

arch/s390/kernel/mcount64.S

+7 −20

Original line number	Diff line number	Diff line
		@@ -18,12 +18,6 @@ _mcount:
		#ifdef CONFIG_DYNAMIC_FTRACE
		br %r14

		.data
		.globl ftrace_dyn_func
		ftrace_dyn_func:
		.quad ftrace_stub
		.previous

		.globl ftrace_caller
		ftrace_caller:
		#endif
		@@ -37,26 +31,19 @@ ftrace_caller:
		stg %r1,__SF_BACKCHAIN(%r15)
		lgr %r2,%r14
		lg %r3,168(%r15)
		#ifdef CONFIG_DYNAMIC_FTRACE
		larl %r14,ftrace_dyn_func
		#else
		larl %r14,ftrace_trace_function
		#endif
		lg %r14,0(%r14)
		basr %r14,%r14
		#ifdef CONFIG_FUNCTION_GRAPH_TRACER
		#ifdef CONFIG_DYNAMIC_FTRACE
		lg %r2,168(%r15)
		lg %r3,272(%r15)
		.globl ftrace_graph_caller
		ftrace_graph_caller:
		# This unconditional branch gets runtime patched. Change only if
		# you know what you are doing. See ftrace_enable_graph_caller().
		j 0f
		#endif
		lg %r2,272(%r15)
		lg %r3,168(%r15)
		brasl %r14,prepare_ftrace_return
		stg %r2,168(%r15)
		0:
		# The bras instruction gets runtime patched to call prepare_ftrace_return.
		# See ftrace_enable_ftrace_graph_caller. The patched instruction is:
		# bras %r14,prepare_ftrace_return
		bras %r14,0f
		0: stg %r2,168(%r15)
		#endif
		aghi %r15,160
		lmg %r2,%r5,32(%r15)