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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 12/12] ARM: entry: Make asm coproc dispatch code NWFPE only
Date: Mon, 20 Mar 2023 14:18:45 +0100	[thread overview]
Message-ID: <20230320131845.3138015-13-ardb@kernel.org> (raw)
In-Reply-To: <20230320131845.3138015-1-ardb@kernel.org>

Now that we can dispatch all VFP and iWMMXT related undef exceptions
using undef hooks implemented in C code, we no longer need the asm entry
code that takes care of this unless we are using FPE. As this means it
is ARM only, we can also remove the Thumb2 specific decorations.

It also means the non-standard, asm-only calling convention where
returning via LR means failure and returning via R9 means success is now
only used on legacy platforms that lack any kind of function return
prediction, avoiding the associated performance impact.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/arm/kernel/entry-armv.S | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 0367c9581c1f05a6..5552179faf7a469e 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -532,8 +532,9 @@ ENDPROC(__und_usr)
  * IRQs enabled, FIQs enabled.
  */
 call_fpe:
-	badr	r9, ret_from_exception
-	badr	lr, __und_usr_fault_32
+#ifdef CONFIG_FPE_NWFPE
+	adr	r9, ret_from_exception
+	adr	lr, __und_usr_fault_32
 
 	sub	r4, r2, #4			@ ARM instr at LR - 4
 USERL(	4b,	ldrt r0, [r4])
@@ -554,9 +555,7 @@ ARM_BE8(rev	r0, r0)				@ little endian instruction
 	teqeq	r5, #1 << TIF_USING_IWMMXT	@ check whether it is set
 	beq	iwmmxt_task_enable		@ branch if set
 #endif
- ARM(	add	pc, pc, r8, lsr #6	)
- THUMB(	lsr	r8, r8, #6		)
- THUMB(	add	pc, r8			)
+	add	pc, pc, r8, lsr #6
 	nop
 
 	ret.w	lr				@ CP#0
@@ -598,6 +597,7 @@ ENTRY(fp_enter)
 ENTRY(no_fp)
 	ret	lr
 ENDPROC(no_fp)
+#endif
 
 __und_usr_fault_32:
 	mov	r1, #4
-- 
2.39.2


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  parent reply	other threads:[~2023-03-20 13:20 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-20 13:18 [PATCH v4 00/12] ARM: vfp: Switch to C API to en/disable softirqs Ard Biesheuvel
2023-03-20 13:18 ` [PATCH v4 01/12] ARM: vfp: Pass thread_info pointer to vfp_support_entry Ard Biesheuvel
2023-03-20 13:18 ` [PATCH v4 02/12] ARM: vfp: Pass successful return address via register R3 Ard Biesheuvel
2023-03-20 13:18 ` [PATCH v4 03/12] ARM: vfp: Fix broken softirq handling with instrumentation enabled Ard Biesheuvel
2023-04-09 14:29   ` Linux regression tracking (Thorsten Leemhuis)
2023-04-10 20:15     ` Guenter Roeck
2023-03-20 13:18 ` [PATCH v4 04/12] ARM: entry: Fix iWMMXT TIF flag handling Ard Biesheuvel
2023-03-21 14:32   ` Linus Walleij
2023-03-21 19:19     ` Nicolas Pitre
2023-03-21 19:32       ` Ard Biesheuvel
2023-03-20 13:18 ` [PATCH v4 05/12] ARM: vfp: Record VFP bounces as perf emulation faults Ard Biesheuvel
2023-03-21 14:33   ` Linus Walleij
2023-03-20 13:18 ` [PATCH v4 06/12] ARM: vfp: Remove workaround for Feroceon CPUs Ard Biesheuvel
2023-03-21 14:44   ` Linus Walleij
2023-03-21 15:42     ` Ard Biesheuvel
2023-03-21 20:40       ` Linus Walleij
2023-03-22  7:26       ` Arnd Bergmann
2023-03-21 20:00     ` Nicolas Pitre
2023-03-20 13:18 ` [PATCH v4 07/12] ARM: vfp: Reimplement VFP exception entry in C code Ard Biesheuvel
2023-03-20 13:18 ` [PATCH v4 08/12] ARM: kernel: Get rid of thread_info::used_cp[] array Ard Biesheuvel
2023-03-21 14:58   ` Linus Walleij
2023-03-20 13:18 ` [PATCH v4 09/12] ARM: vfp: Use undef hook for handling VFP exceptions Ard Biesheuvel
2023-03-21 14:59   ` Linus Walleij
2023-03-21 15:41     ` Ard Biesheuvel
2023-03-20 13:18 ` [PATCH v4 10/12] ARM: entry: Disregard Thumb undef exception in coproc dispatch Ard Biesheuvel
2023-03-21 15:05   ` Linus Walleij
2023-03-20 13:18 ` [PATCH v4 11/12] ARM: iwmmxt: Use undef hook to enable coprocessor for task Ard Biesheuvel
2023-03-21 15:06   ` Linus Walleij
2023-03-20 13:18 ` Ard Biesheuvel [this message]
2023-03-21 15:11   ` [PATCH v4 12/12] ARM: entry: Make asm coproc dispatch code NWFPE only Linus Walleij
2023-03-23  2:44 ` [PATCH v4 00/12] ARM: vfp: Switch to C API to en/disable softirqs Guenter Roeck
2023-03-23  8:33   ` Ard Biesheuvel

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