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From: Nick Desaulniers <ndesaulniers@google.com>
To: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>,
	Stephen Boyd <swboyd@google.com>,
	Luis Lozano <llozano@google.com>,
	Manoj Gupta <manojgupta@google.com>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Nathan Chancellor <natechancellor@gmail.com>,
	Naohiro Aota <naohiro.aota@wdc.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH] arm64: vdso32: force vdso32 to be compiled as -marm
Date: Tue, 26 May 2020 10:31:14 -0700
Message-ID: <20200526173117.155339-1-ndesaulniers@google.com> (raw)

Custom toolchains that modify the default target to -mthumb cannot
compile the arm64 compat vdso32, as
arch/arm64/include/asm/vdso/compat_gettimeofday.h
contains assembly that's invalid in -mthumb.  Force the use of -marm,
always.

Link: https://bugs.chromium.org/p/chromium/issues/detail?id=1084372
Cc: Stephen Boyd <swboyd@google.com>
Reported-by: Luis Lozano <llozano@google.com>
Tested-by: Manoj Gupta <manojgupta@google.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
Surgeon General's Warning: changing the compiler defaults is not
recommended and can lead to spooky bugs that are hard to reproduce
upstream.

 arch/arm64/kernel/vdso32/Makefile | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile
index 3964738ebbde..c449a293d81e 100644
--- a/arch/arm64/kernel/vdso32/Makefile
+++ b/arch/arm64/kernel/vdso32/Makefile
@@ -104,6 +104,8 @@ VDSO_CFLAGS += -D__uint128_t='void*'
 # (on GCC 4.8 or older, there is unfortunately no way to silence this warning)
 VDSO_CFLAGS += $(call cc32-disable-warning,shift-count-overflow)
 VDSO_CFLAGS += -Wno-int-to-pointer-cast
+# Force vdso to be compiled in ARM mode, not THUMB.
+VDSO_CFLAGS += -marm
 
 VDSO_AFLAGS := $(VDSO_CAFLAGS)
 VDSO_AFLAGS += -D__ASSEMBLY__
-- 
2.27.0.rc0.183.gde8f92d652-goog


             reply index

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-26 17:31 Nick Desaulniers [this message]
2020-05-26 18:55 ` Stephen Boyd
2020-05-26 20:45 ` Will Deacon
2020-05-27 13:53   ` Dave Martin
2020-05-27 17:58     ` Nick Desaulniers
2020-05-27 13:45 ` Robin Murphy
2020-05-27 17:55   ` Nick Desaulniers
2020-05-27 18:08     ` Will Deacon
2020-05-27 18:17       ` Nick Desaulniers
2020-05-28  7:20         ` Will Deacon
2020-06-08 20:57           ` [PATCH v2] arm64: vdso32: add CONFIG_THUMB2_COMPAT_VDSO Nick Desaulniers
2020-06-09 20:35             ` Catalin Marinas
2020-06-09 23:55               ` Nick Desaulniers
2020-06-10  8:47                 ` Will Deacon
2020-06-10 10:29                   ` Catalin Marinas
2020-06-10 10:32                     ` Will Deacon
2020-06-10 11:21             ` Will Deacon
2020-05-27 19:28     ` [PATCH] arm64: vdso32: force vdso32 to be compiled as -marm Robin Murphy
2020-05-27 20:02       ` Robin Murphy
2020-05-27 20:14       ` Nick Desaulniers
2020-05-27 20:31         ` Nick Desaulniers
2020-05-27 21:47           ` Nick Desaulniers
2020-05-28  8:05           ` Peter Smith
2020-05-28  9:41             ` Catalin Marinas
2020-05-28 19:06               ` Nick Desaulniers

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