Commit 02424d89 authored by Ian Munsie's avatar Ian Munsie Committed by Benjamin Herrenschmidt
Browse files

powerpc/ftrace: Implement raw syscall tracepoints on PowerPC 



This patch implements the raw syscall tracepoints on PowerPC and exports
them for ftrace syscalls to use.

To minimise reworking existing code, I slightly re-ordered the thread
info flags such that the new TIF_SYSCALL_TRACEPOINT bit would still fit
within the 16 bits of the andi. instruction's UI field. The instructions
in question are in /arch/powerpc/kernel/entry_{32,64}.S to and the
_TIF_SYSCALL_T_OR_A with the thread flags to see if system call tracing
is enabled.

In the case of 64bit PowerPC, arch_syscall_addr and
arch_syscall_match_sym_name are overridden to allow ftrace syscalls to
work given the unusual system call table structure and symbol names that
start with a period.

Signed-off-by: default avatarIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 3f5785ec

arch/powerpc/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -141,6 +141,7 @@ config PPC 
	select GENERIC_IRQ_SHOW

	select GENERIC_IRQ_SHOW_LEVEL

	select HAVE_RCU_TABLE_FREE if SMP

	select HAVE_SYSCALL_TRACEPOINTS



config EARLY_PRINTK

	bool

arch/powerpc/include/asm/ftrace.h

+14 −0
Original line number Diff line number Diff line
@@ -60,4 +60,18 @@ struct dyn_arch_ftrace { 


#endif



#if defined(CONFIG_FTRACE_SYSCALLS) && defined(CONFIG_PPC64) && !defined(__ASSEMBLY__)

#define ARCH_HAS_SYSCALL_MATCH_SYM_NAME

static inline bool arch_syscall_match_sym_name(const char *sym, const char *name)

{

	/*

	 * Compare the symbol name with the system call name. Skip the .sys or .SyS

	 * prefix from the symbol name and the sys prefix from the system call name and

	 * just match the rest. This is only needed on ppc64 since symbol names on

	 * 32bit do not start with a period so the generic function will work.

	 */

	return !strcmp(sym + 4, name + 3);

}

#endif /* CONFIG_FTRACE_SYSCALLS && CONFIG_PPC64 && !__ASSEMBLY__ */



#endif /* _ASM_POWERPC_FTRACE */

arch/powerpc/include/asm/syscall.h

+5 −0
Original line number Diff line number Diff line
@@ -15,6 +15,11 @@ 


#include <linux/sched.h>



/* ftrace syscalls requires exporting the sys_call_table */

#ifdef CONFIG_FTRACE_SYSCALLS

extern const unsigned long *sys_call_table;

#endif /* CONFIG_FTRACE_SYSCALLS */



static inline long syscall_get_nr(struct task_struct *task,

				  struct pt_regs *regs)

{

arch/powerpc/include/asm/thread_info.h

+5 −2
Original line number Diff line number Diff line
@@ -110,7 +110,8 @@ static inline struct thread_info *current_thread_info(void) 
#define TIF_NOERROR		12	/* Force successful syscall return */

#define TIF_NOTIFY_RESUME	13	/* callback before returning to user */

#define TIF_FREEZE		14	/* Freezing for suspend */

#define TIF_RUNLATCH		15	/* Is the runlatch enabled? */

#define TIF_SYSCALL_TRACEPOINT	15	/* syscall tracepoint instrumentation */

#define TIF_RUNLATCH		16	/* Is the runlatch enabled? */



/* as above, but as bit values */

#define _TIF_SYSCALL_TRACE	(1<<TIF_SYSCALL_TRACE)
@@ -127,8 +128,10 @@ static inline struct thread_info *current_thread_info(void) 
#define _TIF_NOERROR		(1<<TIF_NOERROR)

#define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)

#define _TIF_FREEZE		(1<<TIF_FREEZE)

#define _TIF_SYSCALL_TRACEPOINT	(1<<TIF_SYSCALL_TRACEPOINT)

#define _TIF_RUNLATCH		(1<<TIF_RUNLATCH)

#define _TIF_SYSCALL_T_OR_A	(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SECCOMP)

#define _TIF_SYSCALL_T_OR_A	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \

				 _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT)



#define _TIF_USER_WORK_MASK	(_TIF_SIGPENDING | _TIF_NEED_RESCHED | \

				 _TIF_NOTIFY_RESUME)

arch/powerpc/kernel/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -109,6 +109,7 @@ obj-$(CONFIG_PPC_IO_WORKAROUNDS) += io-workarounds.o 


obj-$(CONFIG_DYNAMIC_FTRACE)	+= ftrace.o

obj-$(CONFIG_FUNCTION_GRAPH_TRACER)	+= ftrace.o

obj-$(CONFIG_FTRACE_SYSCALLS)	+= ftrace.o

obj-$(CONFIG_PERF_EVENTS)	+= perf_callchain.o



obj-$(CONFIG_PPC_PERF_CTRS)	+= perf_event.o

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