From cea8cd498f4f1c30ea27e3664b3c671e495c4fce Mon Sep 17 00:00:00 2001 From: Matt Redfearn Date: Tue, 8 Aug 2017 13:22:33 +0100 Subject: [PATCH] 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. Fixes: bb9bc4689b9c ("MIPS: Calculate microMIPS ra properly when unwinding the stack") Suggested-by: Paul Burton Signed-off-by: Matt Redfearn Reviewed-by: James Hogan Cc: Marcin Nowakowski Cc: Miodrag Dinic Cc: Ingo Molnar Cc: David Daney Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/16957/ Signed-off-by: Ralf Baechle --- 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 516089f8c6e7..debc0410a2d5 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;