[PATCH 4/8] ARM: kernel: Get rid of thread_info::used_cp[] array

[Ard Biesheuvel]

We keep track of which coprocessor triggered a fault in the used_cp[]
array in thread_info, but this data is never used anywhere. So let's
remove it.

Linus did some digging and found out that the last user of this field
was removed in commit bb1a773d5b6b ("kill unused dump_fpu() instances").

Reviewed-by: Linus Walleij <linus.walleij at linaro.org>
Signed-off-by: Ard Biesheuvel <ardb at kernel.org>
---
 arch/arm/include/asm/thread_info.h | 1 -
 arch/arm/kernel/asm-offsets.c      | 1 -
 arch/arm/kernel/entry-armv.S       | 6 ------
 arch/arm/kernel/process.c          | 1 -
 arch/arm/kernel/ptrace.c           | 2 --
 5 files changed, 11 deletions(-)

diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
index 7f092cb55a417154..85c5f1e02ebf83ca 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -66,7 +66,6 @@ struct thread_info {
 	__u32			cpu_domain;	/* cpu domain */
 	struct cpu_context_save	cpu_context;	/* cpu context */
 	__u32			abi_syscall;	/* ABI type and syscall nr */
-	__u8			used_cp[16];	/* thread used copro */
 	unsigned long		tp_value[2];	/* TLS registers */
 	union fp_state		fpstate __attribute__((aligned(8)));
 	union vfp_state		vfpstate;
diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c
index 38121c59cbc26cdd..f9c7111c1d65ffda 100644
--- a/arch/arm/kernel/asm-offsets.c
+++ b/arch/arm/kernel/asm-offsets.c
@@ -47,7 +47,6 @@ int main(void)
   DEFINE(TI_CPU_DOMAIN,		offsetof(struct thread_info, cpu_domain));
   DEFINE(TI_CPU_SAVE,		offsetof(struct thread_info, cpu_context));
   DEFINE(TI_ABI_SYSCALL,	offsetof(struct thread_info, abi_syscall));
-  DEFINE(TI_USED_CP,		offsetof(struct thread_info, used_cp));
   DEFINE(TI_TP_VALUE,		offsetof(struct thread_info, tp_value));
   DEFINE(TI_FPSTATE,		offsetof(struct thread_info, fpstate));
 #ifdef CONFIG_VFP
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index c39303e5c23470e6..ba47f6aac5ff8692 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -591,9 +591,6 @@ call_fpe:
 	and	r8, r0, r5
 	cmp	r8, r7				@ NEON instruction?
 	bne	2b
-	mov	r7, #1
-	strb	r7, [r10, #TI_USED_CP + 10]	@ mark CP#10 as used
-	strb	r7, [r10, #TI_USED_CP + 11]	@ mark CP#11 as used
 	b	do_vfp				@ let VFP handler handle this
 1:
 #endif
@@ -601,9 +598,6 @@ call_fpe:
 	tstne	r0, #0x04000000			@ bit 26 set on both ARM and Thumb-2
 	reteq	lr
 	and	r8, r0, #0x00000f00		@ mask out CP number
-	mov	r7, #1
-	add	r6, r10, r8, lsr #8		@ add used_cp[] array offset first
-	strb	r7, [r6, #TI_USED_CP]		@ set appropriate used_cp[]
 #ifdef CONFIG_IWMMXT
 	@ Test if we need to give access to iWMMXt coprocessors
 	ldr	r5, [r10, #TI_FLAGS]
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 0e8ff85890adec07..e16ed102960cb01d 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -222,7 +222,6 @@ void flush_thread(void)
 
 	flush_ptrace_hw_breakpoint(tsk);
 
-	memset(thread->used_cp, 0, sizeof(thread->used_cp));
 	memset(&tsk->thread.debug, 0, sizeof(struct debug_info));
 	memset(&thread->fpstate, 0, sizeof(union fp_state));
 
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index 2d8e2516906b6b4a..2b945b9bd36624a9 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -584,8 +584,6 @@ static int fpa_set(struct task_struct *target,
 {
 	struct thread_info *thread = task_thread_info(target);
 
-	thread->used_cp[1] = thread->used_cp[2] = 1;
-
 	return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
 		&thread->fpstate,
 		0, sizeof(struct user_fp));
-- 
2.39.2