From: Szabolcs Nagy <szabolcs.nagy@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: Mark Rutland <mark.rutland@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Will Deacon <will@kernel.org>,
Tamas Zsoldos <tamas.zsoldos@arm.com>
Subject: arm64 vdso might miss .eh_frame
Date: Wed, 15 Apr 2020 10:23:36 +0100 [thread overview]
Message-ID: <20200415092336.GK987@arm.com> (raw)
On aarch64 linux gcc uses -fasynchronous-unwind-tables -funwind-tables
by default since gcc-8, so now the de facto platform ABI is to allow
unwinding from async signal handlers.
However on bare metal targets (aarch64-none-elf), and on old gcc,
async and sync unwind tables are not enabled by default to avoid
runtime memory costs.
This means if linux is built with a baremetal toolchain the vdso.so
may not have unwind tables which breaks our (undocumented) platform
ABI guarantee in userspace. So adding -fasynchronous-unwind-tables
explicitly to the vgettimeofday.o cflags would be nice (the other
objects in the vdso seem to be asm).
There was also a report that android clang built linux vdso.so lacks
.eh_frame completely, that may be a missing --eh-frame-hdr or different
platform ABI on android, Tamas on cc may be able to verify this.
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next reply other threads:[~2020-04-15 9:23 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-15 9:23 Szabolcs Nagy [this message]
2020-04-28 7:34 ` arm64 vdso might miss .eh_frame Will Deacon
2020-04-28 10:54 ` Vincenzo Frascino
2020-04-28 11:11 ` Mark Rutland
2020-04-28 11:15 ` Vincenzo Frascino
2020-04-28 11:58 ` Will Deacon
2020-04-28 13:40 ` Vincenzo Frascino
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