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author | Andrew Turner <andrew@FreeBSD.org> | 2018-07-16 18:21:29 +0000 |
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committer | Andrew Turner <andrew@FreeBSD.org> | 2018-07-16 18:21:29 +0000 |
commit | 4802a2cb544357ed2ce77a7df74813c85c1f69b6 (patch) | |
tree | 0a9792632f370f5ce2242e0bc1d0ade620448355 | |
parent | a9dc38def44742322a94bce24a34755bb8b7754f (diff) | |
download | src-4802a2cb544357ed2ce77a7df74813c85c1f69b6.tar.gz src-4802a2cb544357ed2ce77a7df74813c85c1f69b6.zip |
Don't use the static keyword with DPCPU defines in arm64 modules.
On arm64 compiler will create PC-relative loads and stores for static data.
This means it doesn't emit a relocation. Unfortunately the in-kernel linker
expects there to be one for DPCPU defines so it can modify its value so the
code will use the correct DPCPU region.
To workaround the lack of a relocation with static data remove it when
building modules on arm64. The kernel is unaffected as it doesn't rely on
modifying these relocations to find the data.
PR: 225684
Reported by: Johannes Lundberg <johalun0@gmail.com>
Reported by: Jose Luis Duran <jlduran@gmail.com>
Reported by: Greg V <greg@unrelenting.technology>
Reviewed by: bz
Sponsored by: ABT Systems Ltd
Differential Revision: https://reviews.freebsd.org/D16145
Notes
Notes:
svn path=/head/; revision=336349
-rw-r--r-- | sys/sys/pcpu.h | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/sys/sys/pcpu.h b/sys/sys/pcpu.h index cba9d6e89797..9057cab20698 100644 --- a/sys/sys/pcpu.h +++ b/sys/sys/pcpu.h @@ -84,8 +84,26 @@ extern uintptr_t dpcpu_off[]; /* struct _hack is to stop this from being used with the static keyword. */ #define DPCPU_DEFINE(t, n) \ struct _hack; t DPCPU_NAME(n) __section(DPCPU_SETNAME) __used +#if defined(KLD_MODULE) && defined(__aarch64__) +/* + * On some architectures the compiler will use PC-relative load to + * find the address of DPCPU data with the static keyword. We then + * use this to find the offset of the data in a per-CPU region. + * This works for in the kernel as we can allocate the space ahead + * of time, however modules need to allocate a sepatate space and + * then use relocations to fix the address of the data. As + * PC-relative data doesn't have a relocation there is nothing for + * the kernel module linker to fix so data is accessed from the + * wrong location. + * + * This is a workaround until a better solution can be found. +*/ +#define DPCPU_DEFINE_STATIC(t, n) \ + t DPCPU_NAME(n) __section(DPCPU_SETNAME) __used +#else #define DPCPU_DEFINE_STATIC(t, n) \ static t DPCPU_NAME(n) __section(DPCPU_SETNAME) __used +#endif /* * Accessors with a given base. |