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Do not use b.cs instruction to jump to cerror.

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The conditional jump can only be performed to targets up to 1MB in
either direction and does not work too well when linker places cerror
further that that from the caller. In that case linker will complain
about relocation overflows.

Reviewed by: emaste, andrew
Differential Revision:  https://reviews.freebsd.org/D10305
This commit is contained in:
Alexander Kabaev 2017-04-07 22:58:20 +00:00
parent fc5bae39c0
commit 07b49497db
1 changed files with 10 additions and 2 deletions
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12
lib/libc/aarch64/SYS.h
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@ -45,12 +45,19 @@ ENTRY(__sys_##name); \
ret; \
END(__sys_##name)
/*
* Conditional jumps can only go up to one megabyte in either
* direction, and cerror can be located anywhere, so we have
* to jump around to use more capable unconditional branch
* instruction.
*/
#define PSEUDO(name) \
ENTRY(__sys_##name); \
WEAK_REFERENCE(__sys_##name, _##name); \
_SYSCALL(name); \
b.cs cerror; \
b.cs 1f; \
ret; \
1: b cerror; \
END(__sys_##name)
#define RSYSCALL(name) \
@ -58,6 +65,7 @@ ENTRY(__sys_##name); \
WEAK_REFERENCE(__sys_##name, name); \
WEAK_REFERENCE(__sys_##name, _##name); \
_SYSCALL(name); \
b.cs cerror; \
b.cs 1f; \
ret; \
1: b cerror; \
END(__sys_##name)