linux-kernel - Re: [PATCH v2 1/5] elf: Define note name macros

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Message-ID: <70daf544-f59f-404b-bec0-0d60e892a9e9@daynix.com>
Date: Mon, 6 Jan 2025 14:07:47 +0900
From: Akihiko Odaki <akihiko.odaki@...nix.com>
To: Baoquan He <bhe@...hat.com>
Cc: Eric Biederman <ebiederm@...ssion.com>, Kees Cook <kees@...nel.org>,
 Catalin Marinas <catalin.marinas@....com>, Mark Brown <broonie@...nel.org>,
 Dave Martin <Dave.Martin@....com>, Vivek Goyal <vgoyal@...hat.com>,
 Dave Young <dyoung@...hat.com>, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
 linux-s390@...r.kernel.org, kexec@...ts.infradead.org, devel@...nix.com
Subject: Re: [PATCH v2 1/5] elf: Define note name macros

On 2025/01/06 11:21, Baoquan He wrote:
> On 01/04/25 at 11:38pm, Akihiko Odaki wrote:
>> elf.h had a comment saying:
>>> Notes used in ET_CORE. Architectures export some of the arch register
>>> sets using the corresponding note types via the PTRACE_GETREGSET and
>>> PTRACE_SETREGSET requests.
>>> The note name for these types is "LINUX", except NT_PRFPREG that is
>>> named "CORE".
>>
>> However, NT_PRSTATUS is also named "CORE". It is also unclear what
>> "these types" refers to.
>>
>> To fix these problems, define a name for each note type. The added
>> definitions are macros so the kernel and userspace can directly refer to
>> them.
>>
>> Signed-off-by: Akihiko Odaki <akihiko.odaki@...nix.com>
>> ---
>>   include/uapi/linux/elf.h | 86 ++++++++++++++++++++++++++++++++++++++++++++++--
>>   1 file changed, 83 insertions(+), 3 deletions(-)
>>
>> diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h
>> index b44069d29cec..014b705b97d7 100644
>> --- a/include/uapi/linux/elf.h
>> +++ b/include/uapi/linux/elf.h
>> @@ -372,8 +372,6 @@ typedef struct elf64_shdr {
>>    * Notes used in ET_CORE. Architectures export some of the arch register sets
>>    * using the corresponding note types via the PTRACE_GETREGSET and
>>    * PTRACE_SETREGSET requests.
>> - * The note name for these types is "LINUX", except NT_PRFPREG that is named
>> - * "CORE".
>>    */
>>   #define NT_PRSTATUS	1
>>   #define NT_PRFPREG	2
>> @@ -460,9 +458,91 @@ typedef struct elf64_shdr {
>>   #define NT_LOONGARCH_HW_BREAK	0xa05   /* LoongArch hardware breakpoint registers */
>>   #define NT_LOONGARCH_HW_WATCH	0xa06   /* LoongArch hardware watchpoint registers */
>>   
>> -/* Note types with note name "GNU" */
>> +/* Note used in ET_EXEC and ET_DYN. */
>>   #define NT_GNU_PROPERTY_TYPE_0	5
>>   
>> +/* Note names */
>> +#define NN_PRSTATUS	"CORE"
>> +#define NN_PRFPREG	"CORE"
>> +#define NN_PRPSINFO	"CORE"
>> +#define NN_TASKSTRUCT	"CORE"
>> +#define NN_AUXV	"CORE"
>> +#define NN_SIGINFO	"CORE"
>> +#define NN_FILE	"CORE"
>> +#define NN_PRXFPREG	"LINUX"
> 
> No objection to make them clearer. Thanks for the effort.
> 
> Wondering where below arch specific macros are used. So you just
> added all NN_xxx for the corresponding NT_xxx? Not sure if this is
> needed if we don't use them at all in the current kernel.

Indeed I just added all NN_xxx. The kernel won't use the macros that are 
defined as "LINUX"; fs/binfmt_elf.c uses "LINUX" by default as the notes 
named "CORE" or "GNU" are exceptional.

Userspace applications may still be interested in these macros as 
demonstrated in:
https://lore.kernel.org/r/Z3f7zJwu8bu8HYln@e133380.arm.com

These macros also serve as documentation; correcting and clarifying the 
documentation is the main purpose of this series.

> 
>> +#define NN_PPC_VMX	"LINUX"
>> +#define NN_PPC_SPE	"LINUX"
>> +#define NN_PPC_VSX	"LINUX"
>> +#define NN_PPC_TAR	"LINUX"
>> +#define NN_PPC_PPR	"LINUX"
>> +#define NN_PPC_DSCR	"LINUX"
>> +#define NN_PPC_EBB	"LINUX"
>> +#define NN_PPC_PMU	"LINUX"
>> +#define NN_PPC_TM_CGPR	"LINUX"
>> +#define NN_PPC_TM_CFPR	"LINUX"
>> +#define NN_PPC_TM_CVMX	"LINUX"
>> +#define NN_PPC_TM_CVSX	"LINUX"
>> +#define NN_PPC_TM_SPR	"LINUX"
>> +#define NN_PPC_TM_CTAR	"LINUX"
>> +#define NN_PPC_TM_CPPR	"LINUX"
>> +#define NN_PPC_TM_CDSCR	"LINUX"
>> +#define NN_PPC_PKEY	"LINUX"
>> +#define NN_PPC_DEXCR	"LINUX"
>> +#define NN_PPC_HASHKEYR	"LINUX"
>> +#define NN_386_TLS	"LINUX"
>> +#define NN_386_IOPERM	"LINUX"
>> +#define NN_X86_XSTATE	"LINUX"
>> +#define NN_X86_SHSTK	"LINUX"
>> +#define NN_X86_XSAVE_LAYOUT	"LINUX"
>> +#define NN_S390_HIGH_GPRS	"LINUX"
>> +#define NN_S390_TIMER	"LINUX"
>> +#define NN_S390_TODCMP	"LINUX"
>> +#define NN_S390_TODPREG	"LINUX"
>> +#define NN_S390_CTRS	"LINUX"
>> +#define NN_S390_PREFIX	"LINUX"
>> +#define NN_S390_LAST_BREAK	"LINUX"
>> +#define NN_S390_SYSTEM_CALL	"LINUX"
>> +#define NN_S390_TDB	"LINUX"
>> +#define NN_S390_VXRS_LOW	"LINUX"
>> +#define NN_S390_VXRS_HIGH	"LINUX"
>> +#define NN_S390_GS_CB	"LINUX"
>> +#define NN_S390_GS_BC	"LINUX"
>> +#define NN_S390_RI_CB	"LINUX"
>> +#define NN_S390_PV_CPU_DATA	"LINUX"
>> +#define NN_ARM_VFP	"LINUX"
>> +#define NN_ARM_TLS	"LINUX"
>> +#define NN_ARM_HW_BREAK	"LINUX"
>> +#define NN_ARM_HW_WATCH	"LINUX"
>> +#define NN_ARM_SYSTEM_CALL	"LINUX"
>> +#define NN_ARM_SVE	"LINUX"
>> +#define NN_ARM_PAC_MASK	"LINUX"
>> +#define NN_ARM_PACA_KEYS	"LINUX"
>> +#define NN_ARM_PACG_KEYS	"LINUX"
>> +#define NN_ARM_TAGGED_ADDR_CTRL	"LINUX"
>> +#define NN_ARM_PAC_ENABLED_KEYS	"LINUX"
>> +#define NN_ARM_SSVE	"LINUX"
>> +#define NN_ARM_ZA	"LINUX"
>> +#define NN_ARM_ZT	"LINUX"
>> +#define NN_ARM_FPMR	"LINUX"
>> +#define NN_ARM_POE	"LINUX"
>> +#define NN_ARM_GCS	"LINUX"
>> +#define NN_ARC_V2	"LINUX"
>> +#define NN_VMCOREDD	"LINUX"
>> +#define NN_MIPS_DSP	"LINUX"
>> +#define NN_MIPS_FP_MODE	"LINUX"
>> +#define NN_MIPS_MSA	"LINUX"
>> +#define NN_RISCV_CSR	"LINUX"
>> +#define NN_RISCV_VECTOR	"LINUX"
>> +#define NN_RISCV_TAGGED_ADDR_CTRL	"LINUX"
>> +#define NN_LOONGARCH_CPUCFG	"LINUX"
>> +#define NN_LOONGARCH_CSR	"LINUX"
>> +#define NN_LOONGARCH_LSX	"LINUX"
>> +#define NN_LOONGARCH_LASX	"LINUX"
>> +#define NN_LOONGARCH_LBT	"LINUX"
>> +#define NN_LOONGARCH_HW_BREAK	"LINUX"
>> +#define NN_LOONGARCH_HW_WATCH	"LINUX"
>> +#define NN_GNU_PROPERTY_TYPE_0	"GNU"
>> +
>>   /* Note header in a PT_NOTE section */
>>   typedef struct elf32_note {
>>     Elf32_Word	n_namesz;	/* Name size */
>>
>> -- 
>> 2.47.1
>>
>