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uclibc: ARC: Support syscall ABI v4

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When used with GCC 6 ABIv4 is used.
Missing this patch leads to numerous runtime errors.

The patch has already been accepted in uclibc-ng:
http://cgit.uclibc-ng.org/cgi/cgit/uclibc-ng.git/commit/?id=3e40f9669279f005f7154892539166f5081fbcb2

So the patch should be removed after update to a new version of uclibc-ng.

Signed-off-by: Vlad Zakharov <vzakhar@synopsys.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
This commit is contained in:
Zakharov Vlad 2016-08-18 08:52:33 +03:00 committed by Thomas Petazzoni
parent ba4af1a06d
commit 9914215d89
1 changed files with 54 additions and 0 deletions
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54
package/uclibc/0003-ARC-Support-syscall-ABI-v4.patch Normal file
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@ -0,0 +1,54 @@
From 3e40f9669279f005f7154892539166f5081fbcb2 Mon Sep 17 00:00:00 2001
From: Vineet Gupta <Vineet.Gupta1@synopsys.com>
Date: Tue, 16 Aug 2016 15:04:27 -0700
Subject: [PATCH] ARC: Support syscall ABI v4
The syscall ABI includes the gcc functional calling ABI since a syscall
implies userland caller and kernel callee.
The current gcc ABI (v3) for ARCv2 ISA required 64-bit data be passed in
even-odd register pairs, (potentially punching reg holes when passing such
values as args). This was partly driven by the fact that the double-word
LDD/STD instructions in ARCv2 expect the register alignment and thus gcc
forcing this avoids extra MOV at the cost of a few unused register (which we
have plenty anyways).
This however was rejected as part of upstreaming gcc port to HS. So the new
ABI v4 doesn't enforce the even-odd reg restriction.
Do note that for ARCompact ISA builds v3 and v4 are practically the same in
terms of gcc code generation.
This change is dormant for now (gcc 4.8.x based tools) and will only kick
in with switch to gcc 6.x based tools.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Vlad Zakharov <vzakhar@synopsys.com>
---
libc/sysdeps/linux/arc/bits/uClibc_arch_features.h | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/libc/sysdeps/linux/arc/bits/uClibc_arch_features.h b/libc/sysdeps/linux/arc/bits/uClibc_arch_features.h
index 5160724..94e089d 100755
--- a/libc/sysdeps/linux/arc/bits/uClibc_arch_features.h
+++ b/libc/sysdeps/linux/arc/bits/uClibc_arch_features.h
@@ -41,8 +41,14 @@
/* The default ';' is a comment on ARC. */
#define __UCLIBC_ASM_LINE_SEP__ `
-/* does your target align 64bit values in register pairs ? (32bit arches only) */
-#if defined(__A7__)
+/* does your target align 64bit values in register pairs ? (32bit arches only)
+ * - ARC700 never had any constraint on reg pairs (even if ABI v3)
+ * - Inital HS ABI (v3: non upstream gcc) had 64-bit data aligned in even-odd
+ * reg pairs (thus allowed reg holes when passing such args to calls)
+ * - Upstream gcc (6.x) HS ABI doesn't have that restriction
+ */
+
+#if defined(__A7__) || (__GNUC__ > 4)
#undef __UCLIBC_SYSCALL_ALIGN_64BIT__
#else
#define __UCLIBC_SYSCALL_ALIGN_64BIT__
--
2.7.4