[PATCH v4 08/12] ARM: kernel: Get rid of thread_info::used_cp[] array

From: Ard Biesheuvel <ardb@kernel.org>
To: linux-arm-kernel@lists.infradead.org, linux@armlinux.org.uk
Cc: Ard Biesheuvel <ardb@kernel.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	Guenter Roeck <linux@roeck-us.net>,
	Peter Zijlstra <peterz@infradead.org>,
	Linus Walleij <linus.walleij@linaro.org>,
	Arnd Bergmann <arnd@arndb.de>
Subject: [PATCH v4 08/12] ARM: kernel: Get rid of thread_info::used_cp[] array
Date: Mon, 20 Mar 2023 14:18:41 +0100	[thread overview]
Message-ID: <20230320131845.3138015-9-ardb@kernel.org> (raw)
In-Reply-To: <20230320131845.3138015-1-ardb@kernel.org>

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.

Signed-off-by: Ard Biesheuvel <ardb@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 c5d2f07994fb0d87..cae8e31ce2cbde41 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
 	tst	r8, #0xe << 8			@ CP 0 or 1?
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index f811733a8fc574b4..343451cab8c4f5df 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -223,7 +223,6 @@ 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


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