linux-kernel - [PATCH 2/2] ARC: don't align ret_from

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Message-Id: <20200311162644.7667-2-Eugeniy.Paltsev@synopsys.com>
Date:   Wed, 11 Mar 2020 19:26:44 +0300
From:   Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>
To:     linux-snps-arc@...ts.infradead.org,
        Vineet Gupta <Vineet.Gupta1@...opsys.com>
Cc:     linux-kernel@...r.kernel.org,
        Alexey Brodkin <Alexey.Brodkin@...opsys.com>,
        Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>
Subject: [PATCH 2/2] ARC: don't align ret_from_exception function

ARC have a tricky implemented ret_from_exception function.
It is written on ASM and can be called like regular function.
However it has another 'entry point' as it can be called as a
continuation of EV_Trap function.

As we declare "ret_from_exception" using ENTRY macro it may align
"ret_from_exception" by 4 bytes by adding padding before it.
"ret_from_exception" doesn't require alignment by 4 bytes
(as it doesn't go to vector table, etc...) so let's avoid aligning
it by switch from ENTRY (which is alias for SYM_FUNC_START) to
SYM_FUNC_START_NOALIGN macro.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>
---
 arch/arc/kernel/entry-arcv2.S | 2 +-
 arch/arc/kernel/entry.S       | 3 +--
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/arc/kernel/entry-arcv2.S b/arch/arc/kernel/entry-arcv2.S
index 12d5f12d10d2..d482e1507f56 100644
--- a/arch/arc/kernel/entry-arcv2.S
+++ b/arch/arc/kernel/entry-arcv2.S
@@ -260,4 +260,4 @@ debug_marker_ds:
 	sr	r11, [AUX_IRQ_ACT]
 	b	.Lexcept_ret
 
-END(ret_from_exception)
+SYM_FUNC_END(ret_from_exception)
diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S
index 60406ec62eb8..79409b518a09 100644
--- a/arch/arc/kernel/entry.S
+++ b/arch/arc/kernel/entry.S
@@ -280,7 +280,7 @@ END(EV_Trap)
 ;
 ; If ret to user mode do we need to handle signals, schedule() et al.
 
-ENTRY(ret_from_exception)
+SYM_FUNC_START_NOALIGN(ret_from_exception)
 
 	; Pre-{IRQ,Trap,Exception} K/U mode from pt_regs->status32
 	ld  r8, [sp, PT_status32]   ; returning to User/Kernel Mode
@@ -373,4 +373,3 @@ resume_kernel_mode:
 	b	.Lrestore_regs
 
 ##### DONT ADD CODE HERE - .Lrestore_regs actually follows in entry-<isa>.S
-
-- 
2.21.1