diff options
author | Vincent Chen <vincentc@andestech.com> | 2018-11-22 11:14:36 +0800 |
---|---|---|
committer | Greentime Hu <greentime@andestech.com> | 2018-11-22 18:13:27 +0800 |
commit | 44e92e0364adfd7b6759084e02a550d06336d896 (patch) | |
tree | 4fb8af79a5ce25f9467bdc22f44e67f6ae42b6d6 /arch/nds32/include/asm/elf.h | |
parent | 1ac832509f2ea1b566f0c06f98f308f58b03d098 (diff) |
nds32: support denormalized result through FP emulator
Currently, the nds32 FPU dose not support the arithmetic of denormalized
number. When the nds32 FPU finds the result of the instruction is a
denormlized number, the nds32 FPU considers it to be an underflow condition
and rounds the result to an appropriate number. It may causes some loss
of precision. This commit proposes a solution to re-execute the
instruction by the FPU emulator to enhance the precision. To transfer
calculations from user space to kernel space, this feature will enable
the underflow exception trap by default. Enabling this feature may cause
some side effects:
1. Performance loss due to extra FPU exception
2. Need another scheme to control real underflow trap
A new parameter, UDF_trap, which is belong to FPU context is used
to control underflow trap.
User can configure this feature via CONFIG_SUPPORT_DENORMAL_ARITHMETIC
Signed-off-by: Vincent Chen <vincentc@andestech.com>
Acked-by: Greentime Hu <greentime@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>
Diffstat (limited to 'arch/nds32/include/asm/elf.h')
-rw-r--r-- | arch/nds32/include/asm/elf.h | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/arch/nds32/include/asm/elf.h b/arch/nds32/include/asm/elf.h index f5f9cf7e0544..95f3ea253e4c 100644 --- a/arch/nds32/include/asm/elf.h +++ b/arch/nds32/include/asm/elf.h @@ -9,6 +9,7 @@ */ #include <asm/ptrace.h> +#include <asm/fpu.h> typedef unsigned long elf_greg_t; typedef unsigned long elf_freg_t[3]; @@ -159,8 +160,18 @@ struct elf32_hdr; #endif + +#if IS_ENABLED(CONFIG_FPU) +#define FPU_AUX_ENT NEW_AUX_ENT(AT_FPUCW, FPCSR_INIT) +#else +#define FPU_AUX_ENT NEW_AUX_ENT(AT_IGNORE, 0) +#endif + #define ARCH_DLINFO \ do { \ + /* Optional FPU initialization */ \ + FPU_AUX_ENT; \ + \ NEW_AUX_ENT(AT_SYSINFO_EHDR, \ (elf_addr_t)current->mm->context.vdso); \ } while (0) |