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target-mips: indicate presence of IEEE 754-2008 FPU in R6/R5+MSA CPUs 

MIPS Release 6 and MIPS SIMD Architecture make it mandatory to have IEEE
754-2008 FPU which is indicated by CP1 FIR.HAS2008, FCSR.ABS2008 and
FCSR.NAN2008 bits set to 1.

In QEMU we still keep these bits cleared as there is no 2008-NaN support.
However, this now causes problems preventing from running R6 Linux with
the v4.5 kernel. Kernel refuses to execute 2008-NaN ELFs on a CPU
whose FPU does not support 2008-NaN encoding:

  (...)
  VFS: Mounted root (ext4 filesystem) readonly on device 8:0.
  devtmpfs: mounted
  Freeing unused kernel memory: 256K (ffffffff806f0000 - ffffffff80730000)
  request_module: runaway loop modprobe binfmt-464c
  Starting init: /sbin/init exists but couldn't execute it (error -8)
  request_module: runaway loop modprobe binfmt-464c
  Starting init: /bin/sh exists but couldn't execute it (error -8)
  Kernel panic - not syncing: No working init found.  Try passing init= option to kernel. See Linux Documentation/init.txt for guidance.

Therefore always indicate presence of 2008-NaN support in R6 as well as in
R5+MSA CPUs, even though this feature is not yet supported by MIPS in QEMU.

Signed-off-by: Leon Alrae <leon.alrae@imgtec.com>
This commit is contained in:
Leon Alrae 2016-02-24 10:47:10 +00:00
parent ffa6564c9b
commit ba5c79f262
3 changed files with 17 additions and 9 deletions
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3
target-mips/cpu.h
View File

@ -99,6 +99,7 @@ struct CPUMIPSFPUContext {
uint32_t fcr0;
#define FCR0_FREP 29
#define FCR0_UFRP 28
#define FCR0_HAS2008 23
#define FCR0_F64 22
#define FCR0_L 21
#define FCR0_W 20
@ -110,6 +111,8 @@ struct CPUMIPSFPUContext {
#define FCR0_REV 0
/* fcsr */
uint32_t fcr31;
#define FCR31_ABS2008 19
#define FCR31_NAN2008 18
#define SET_FP_COND(num,env) do { ((env).fcr31) |= ((num) ? (1 << ((num) + 24)) : (1 << 23)); } while(0)
#define CLEAR_FP_COND(num,env) do { ((env).fcr31) &= ~((num) ? (1 << ((num) + 24)) : (1 << 23)); } while(0)
#define GET_FP_COND(env) ((((env).fcr31 >> 24) & 0xfe) | (((env).fcr31 >> 23) & 0x1))

1
target-mips/translate.c
View File

@ -20012,6 +20012,7 @@ void cpu_state_reset(CPUMIPSState *env)
env->CP0_PageGrain_rw_bitmask = env->cpu_model->CP0_PageGrain_rw_bitmask;
env->CP0_PageGrain = env->cpu_model->CP0_PageGrain;
env->active_fpu.fcr0 = env->cpu_model->CP1_fcr0;
env->active_fpu.fcr31 = env->cpu_model->CP1_fcr31;
env->msair = env->cpu_model->MSAIR;
env->insn_flags = env->cpu_model->insn_flags;

22
target-mips/translate_init.c
View File

@ -84,6 +84,7 @@ struct mips_def_t {
int32_t CP0_TCStatus_rw_bitmask;
int32_t CP0_SRSCtl;
int32_t CP1_fcr0;
int32_t CP1_fcr31;
int32_t MSAIR;
int32_t SEGBITS;
int32_t PABITS;
@ -421,9 +422,10 @@ static const mips_def_t mips_defs[] =
.CP0_Status_rw_bitmask = 0x3C68FF1F,
.CP0_PageGrain_rw_bitmask = (1U << CP0PG_RIE) | (1 << CP0PG_XIE) |
(1 << CP0PG_ELPA) | (1 << CP0PG_IEC),
.CP1_fcr0 = (1 << FCR0_FREP) | (1 << FCR0_UFRP) | (1 << FCR0_F64) |
(1 << FCR0_L) | (1 << FCR0_W) | (1 << FCR0_D) |
(1 << FCR0_S) | (0x03 << FCR0_PRID),
.CP1_fcr0 = (1 << FCR0_FREP) | (1 << FCR0_UFRP) | (1 << FCR0_HAS2008) |
(1 << FCR0_F64) | (1 << FCR0_L) | (1 << FCR0_W) |
(1 << FCR0_D) | (1 << FCR0_S) | (0x03 << FCR0_PRID),
.CP1_fcr31 = (1 << FCR31_ABS2008) | (1 << FCR31_NAN2008),
.SEGBITS = 32,
.PABITS = 40,
.insn_flags = CPU_MIPS32R5 | ASE_MSA,
@ -458,9 +460,10 @@ static const mips_def_t mips_defs[] =
.CP0_PageGrain = (1 << CP0PG_IEC) | (1 << CP0PG_XIE) |
(1U << CP0PG_RIE),
.CP0_PageGrain_rw_bitmask = 0,
.CP1_fcr0 = (1 << FCR0_FREP) | (1 << FCR0_F64) | (1 << FCR0_L) |
(1 << FCR0_W) | (1 << FCR0_D) | (1 << FCR0_S) |
(0x00 << FCR0_PRID) | (0x0 << FCR0_REV),
.CP1_fcr0 = (1 << FCR0_FREP) | (1 << FCR0_HAS2008) | (1 << FCR0_F64) |
(1 << FCR0_L) | (1 << FCR0_W) | (1 << FCR0_D) |
(1 << FCR0_S) | (0x00 << FCR0_PRID) | (0x0 << FCR0_REV),
.CP1_fcr31 = (1 << FCR31_ABS2008) | (1 << FCR31_NAN2008),
.SEGBITS = 32,
.PABITS = 32,
.insn_flags = CPU_MIPS32R6 | ASE_MICROMIPS,
@ -677,9 +680,10 @@ static const mips_def_t mips_defs[] =
.CP0_PageGrain = (1 << CP0PG_IEC) | (1 << CP0PG_XIE) |
(1U << CP0PG_RIE),
.CP0_PageGrain_rw_bitmask = (1 << CP0PG_ELPA),
.CP1_fcr0 = (1 << FCR0_FREP) | (1 << FCR0_F64) | (1 << FCR0_L) |
(1 << FCR0_W) | (1 << FCR0_D) | (1 << FCR0_S) |
(0x00 << FCR0_PRID) | (0x0 << FCR0_REV),
.CP1_fcr0 = (1 << FCR0_FREP) | (1 << FCR0_HAS2008) | (1 << FCR0_F64) |
(1 << FCR0_L) | (1 << FCR0_W) | (1 << FCR0_D) |
(1 << FCR0_S) | (0x00 << FCR0_PRID) | (0x0 << FCR0_REV),
.CP1_fcr31 = (1 << FCR31_ABS2008) | (1 << FCR31_NAN2008),
.SEGBITS = 48,
.PABITS = 48,
.insn_flags = CPU_MIPS64R6 | ASE_MSA,