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MIPS: microMIPS: Fix decoding of swsp16 instruction

When the immediate encoded in the instruction is accessed, it is sign extended due to being a signed value being assigned to a signed integer. The ISA specifies that this operation is an unsigned operation. The sign extension leads us to incorrectly decode: 801e9c8e: cbf1 sw ra,68(sp) As having an immediate of 1073741809. Since the instruction format does not specify signed/unsigned, and this is currently the only location to use this instuction format, change it to an unsigned immediate.

Matt Redfearn committed 9 years ago

Commit cea8cd41 parent a0ae2b02 files · +2 −2Browse files

Showing the changes to arch/mips/include/uapi (1 of 2 files). Show all

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arch/mips/include/uapi/asm/inst.h+1−1
@@ -981,7 +981,7 @@ struct mm16_r3_format { /* Load from global pointer format */ · 980 unmodified lines
981struct mm16_r5_format { /* Load/store from stack pointer format */981struct mm16_r5_format { /* Load/store from stack pointer format */
982 __BITFIELD_FIELD(unsigned int opcode : 6,982 __BITFIELD_FIELD(unsigned int opcode : 6,
983 __BITFIELD_FIELD(unsigned int rt : 5,983 __BITFIELD_FIELD(unsigned int rt : 5,
984 __BITFIELD_FIELD(signed int simmediate : 5,984 __BITFIELD_FIELD(unsigned int imm : 5,
985 __BITFIELD_FIELD(unsigned int : 16, /* Ignored */985 __BITFIELD_FIELD(unsigned int : 16, /* Ignored */
986 ;))))986 ;))))
987};987};

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