Messages in this thread Patch in this message | | | From | Matt Redfearn <> | Subject | [PATCH v3 4/6] MIPS: microMIPS: Fix decoding of swsp16 instruction | Date | Tue, 8 Aug 2017 13:22:33 +0100 |
| |
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.
Fixes: bb9bc4689b9c ("MIPS: Calculate microMIPS ra properly when unwinding the stack") Suggested-by: Paul Burton <paul.burton@imgtec.com> Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com> Reviewed-by: James Hogan <james.hogan@imgtec.com>
---
Changes in v3: None Changes in v2: None
arch/mips/include/uapi/asm/inst.h | 2 +- arch/mips/kernel/process.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/mips/include/uapi/asm/inst.h b/arch/mips/include/uapi/asm/inst.h index d61897535926..6abea5183d7c 100644 --- a/arch/mips/include/uapi/asm/inst.h +++ b/arch/mips/include/uapi/asm/inst.h @@ -981,7 +981,7 @@ struct mm16_r3_format { /* Load from global pointer format */ struct mm16_r5_format { /* Load/store from stack pointer format */ __BITFIELD_FIELD(unsigned int opcode : 6, __BITFIELD_FIELD(unsigned int rt : 5, - __BITFIELD_FIELD(signed int simmediate : 5, + __BITFIELD_FIELD(unsigned int imm : 5, __BITFIELD_FIELD(unsigned int : 16, /* Ignored */ ;)))) }; diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c index 288a79bd0e72..6fa726b0be01 100644 --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -214,7 +214,7 @@ static inline int is_ra_save_ins(union mips_instruction *ip, int *poff) if (ip->mm16_r5_format.rt != 31) return 0; - *poff = ip->mm16_r5_format.simmediate; + *poff = ip->mm16_r5_format.imm; *poff = (*poff << 2) / sizeof(ulong); return 1; -- 2.7.4
| |