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MIPS: End asm function prologue macros with .insn

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When building a kernel targeting a microMIPS ISA, recent GNU linkers
will fail the link if they cannot determine that the target of a branch
or jump is microMIPS code, with errors such as the following:

    mips-img-linux-gnu-ld: arch/mips/built-in.o: .text+0x542c:
    Unsupported jump between ISA modes; consider recompiling with
    interlinking enabled.
    mips-img-linux-gnu-ld: final link failed: Bad value

or:

    ./arch/mips/include/asm/uaccess.h:1017: warning: JALX to a
    non-word-aligned address

Placing anything other than an instruction at the start of a function
written in assembly appears to trigger such errors. In order to prepare
for allowing us to follow function prologue macros with an EXPORT_SYMBOL
invocation, end the prologue macros (LEAD, NESTED & FEXPORT) with a
.insn directive. This ensures that the start of the function is marked
as code, which always makes sense for functions & safely prevents us
from hitting the link errors described above.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Reviewed-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14508/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Paul Burton 2016-11-07 11:14:09 +00:00 committed by Ralf Baechle
parent 2c0e57eaef
commit 08889582b8
1 changed files with 6 additions and 4 deletions
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10
arch/mips/include/asm/asm.h
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@ -54,7 +54,8 @@
.align 2; \
.type symbol, @function; \
.ent symbol, 0; \
symbol: .frame sp, 0, ra
symbol: .frame sp, 0, ra; \
.insn
/*
* NESTED - declare nested routine entry point
@ -63,8 +64,9 @@ symbol: .frame sp, 0, ra
.globl symbol; \
.align 2; \
.type symbol, @function; \
.ent symbol, 0; \
symbol: .frame sp, framesize, rpc
.ent symbol, 0; \
symbol: .frame sp, framesize, rpc; \
.insn
/*
* END - mark end of function
@ -86,7 +88,7 @@ symbol:
#define FEXPORT(symbol) \
.globl symbol; \
.type symbol, @function; \
symbol:
symbol: .insn
/*
* ABS - export absolute symbol