From 44109c60176ae73924a42a6bef64ef151aba9095 Mon Sep 17 00:00:00 2001 From: "Maciej W. Rozycki" Date: Tue, 15 May 2018 23:34:28 +0100 Subject: MIPS: Add DSP ASE regset support Define an NT_MIPS_DSP core file note type and implement a corresponding regset holding the DSP ASE register context, following the layout of the `mips_dsp_state' structure, except for the DSPControl register stored as a 64-bit rather than 32-bit quantity in a 64-bit note. The lack of DSP ASE register saving to core files can be considered a design flaw with commit e50c0a8fa60d ("Support the MIPS32 / MIPS64 DSP ASE."), leading to an incomplete state being saved. Consequently no DSP ASE regset has been created with commit 7aeb753b5353 ("MIPS: Implement task_user_regset_view."), when regset support was added to the MIPS port. Additionally there is no way for ptrace(2) to correctly access the DSP accumulator registers in n32 processes with the existing interfaces. This is due to 32-bit truncation of data passed with PTRACE_PEEKUSR and PTRACE_POKEUSR requests, which cannot be avoided owing to how the data types for ptrace(3) have been defined. This new NT_MIPS_DSP regset fills the missing interface gap. [paul.burton@mips.com: - Change NT_MIPS_DSP to 0x800 to avoid conflict with NT_VMCOREDD introduced by commit 2724273e8fd0 ("vmcore: add API to collect hardware dump in second kernel"). - Drop stable tag. Whilst I agree the lack of this functionality can be considered a flaw in earlier DSP ASE support, it's still new functionality which doesn't meet up to the requirements set out in Documentation/process/stable-kernel-rules.rst.] Signed-off-by: Maciej W. Rozycki Signed-off-by: Paul Burton References: 7aeb753b5353 ("MIPS: Implement task_user_regset_view.") Patchwork: https://patchwork.linux-mips.org/patch/19330/ Cc: Alexander Viro Cc: James Hogan Cc: Ralf Baechle Cc: linux-fsdevel@vger.kernel.org Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org --- include/uapi/linux/elf.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h index 4e12c423b9fe..e326c99b3881 100644 --- a/include/uapi/linux/elf.h +++ b/include/uapi/linux/elf.h @@ -422,6 +422,7 @@ typedef struct elf64_shdr { #define NT_ARM_SVE 0x405 /* ARM Scalable Vector Extension registers */ #define NT_ARC_V2 0x600 /* ARCv2 accumulator/extra registers */ #define NT_VMCOREDD 0x700 /* Vmcore Device Dump Note */ +#define NT_MIPS_DSP 0x800 /* MIPS DSP ASE registers */ /* Note header in a PT_NOTE section */ typedef struct elf32_note { -- cgit v1.2.3