Commit 5aaeb5c0 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

x86/fpu, sched: Introduce CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT and use it on x86 



Don't burden architectures without dynamic task_struct sizing
with the overhead of dynamic sizing.

Also optimize the x86 code a bit by caching task_struct_size.

Acked-and-Tested-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1437128892-9831-3-git-send-email-mingo@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 0c8c0f03

arch/Kconfig

+4 −0
Original line number Diff line number Diff line
@@ -221,6 +221,10 @@ config ARCH_TASK_STRUCT_ALLOCATOR 
config ARCH_THREAD_INFO_ALLOCATOR

	bool



# Select if arch wants to size task_struct dynamically via arch_task_struct_size:

config ARCH_WANTS_DYNAMIC_TASK_STRUCT

	bool



config HAVE_REGS_AND_STACK_ACCESS_API

	bool

	help

arch/x86/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -41,6 +41,7 @@ config X86 
	select ARCH_USE_CMPXCHG_LOCKREF		if X86_64

	select ARCH_USE_QUEUED_RWLOCKS

	select ARCH_USE_QUEUED_SPINLOCKS

	select ARCH_WANTS_DYNAMIC_TASK_STRUCT

	select ARCH_WANT_FRAME_POINTERS

	select ARCH_WANT_IPC_PARSE_VERSION	if X86_32

	select ARCH_WANT_OPTIONAL_GPIOLIB

arch/x86/kernel/fpu/init.c

+9 −8
Original line number Diff line number Diff line
@@ -4,6 +4,8 @@ 
#include <asm/fpu/internal.h>

#include <asm/tlbflush.h>



#include <linux/sched.h>



/*

 * Initialize the TS bit in CR0 according to the style of context-switches

 * we are using:
@@ -136,16 +138,14 @@ static void __init fpu__init_system_generic(void) 
unsigned int xstate_size;

EXPORT_SYMBOL_GPL(xstate_size);



/* Enforce that 'MEMBER' is the last field of 'TYPE': */

#define CHECK_MEMBER_AT_END_OF(TYPE, MEMBER) \

	BUILD_BUG_ON((sizeof(TYPE) -			\

			offsetof(TYPE, MEMBER) -	\

			sizeof(((TYPE *)0)->MEMBER)) > 	\

			0)				\

	BUILD_BUG_ON(sizeof(TYPE) != offsetofend(TYPE, MEMBER))



/*

 * We append the 'struct fpu' to the task_struct.

 * We append the 'struct fpu' to the task_struct:

 */

int __weak arch_task_struct_size(void)

static void __init fpu__init_task_struct_size(void)

{

	int task_size = sizeof(struct task_struct);
@@ -172,7 +172,7 @@ int __weak arch_task_struct_size(void) 
	CHECK_MEMBER_AT_END_OF(struct thread_struct, fpu);

	CHECK_MEMBER_AT_END_OF(struct task_struct, thread);



	return task_size;

	arch_task_struct_size = task_size;

}



/*
@@ -326,6 +326,7 @@ void __init fpu__init_system(struct cpuinfo_x86 *c) 
	fpu__init_system_generic();

	fpu__init_system_xstate_size_legacy();

	fpu__init_system_xstate();

	fpu__init_task_struct_size();



	fpu__init_system_ctx_switch();

}

arch/x86/kernel/process.c

+1 −1
Original line number Diff line number Diff line
@@ -81,7 +81,7 @@ EXPORT_SYMBOL_GPL(idle_notifier_unregister); 
 */

int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)

{

	memcpy(dst, src, arch_task_struct_size());

	memcpy(dst, src, arch_task_struct_size);



	return fpu__copy(&dst->thread.fpu, &src->thread.fpu);

}

fs/proc/kcore.c

+2 −2
Original line number Diff line number Diff line
@@ -92,7 +92,7 @@ static size_t get_kcore_size(int *nphdr, size_t *elf_buflen) 
			     roundup(sizeof(CORE_STR), 4)) +

			roundup(sizeof(struct elf_prstatus), 4) +

			roundup(sizeof(struct elf_prpsinfo), 4) +

			roundup(arch_task_struct_size(), 4);

			roundup(arch_task_struct_size, 4);

	*elf_buflen = PAGE_ALIGN(*elf_buflen);

	return size + *elf_buflen;

}
@@ -415,7 +415,7 @@ static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff) 
	/* set up the task structure */

	notes[2].name	= CORE_STR;

	notes[2].type	= NT_TASKSTRUCT;

	notes[2].datasz	= arch_task_struct_size();

	notes[2].datasz	= arch_task_struct_size;

	notes[2].data	= current;



	nhdr->p_filesz	+= notesize(&notes[2]);

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