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parisc: Provide an extru_safe() macro to extract unsigned bits 

The extru instruction leaves the most significant 32 bits of the
target register in an undefined state on PA 2.0 systems.
Provide a macro to safely use extru on 32- and 64-bit machines.

Suggested-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
This commit is contained in:
Helge Deller 2021-11-19 22:16:37 +01:00
parent 8d192bec53
commit 169d1a4a2a
1 changed files with 11 additions and 0 deletions
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11
arch/parisc/include/asm/assembly.h
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@ -147,6 +147,17 @@
extrd,u \r, 63-(\sa), 64-(\sa), \t
.endm
/* Extract unsigned for 32- and 64-bit
* The extru instruction leaves the most significant 32 bits of the
* target register in an undefined state on PA 2.0 systems. */
.macro extru_safe r, p, len, t
#ifdef CONFIG_64BIT
extrd,u \r, 32+(\p), \len, \t
#else
extru \r, \p, \len, \t
#endif
.endm
/* load 32-bit 'value' into 'reg' compensating for the ldil
* sign-extension when running in wide mode.
* WARNING!! neither 'value' nor 'reg' can be expressions