[PATCH v5 0/6] elf: Define note name macros

[PATCH v5 0/6] elf: Define note name macros

[Akihiko Odaki]

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.

For userspace program developers
---------------------------------------------------
While the main purpose of new macros is documentation, they are also
hoped to be useful for userspace programs. Please check patch
"elf: Define note name macros" and if you have a suggestion to make it
more convenient for you, please share.

I added the Binutils mailing list to the CC as it contains code to parse
dumps. I'm also planning to share this series on LLVM Discourse.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
---
Changes in v5:
- Noted that patch "elf: Define note name macros" allows removing
  duplicate definitions of note names.
- Reordered NT_GNU_PROPERTY_TYPE_0 to precede notes used in ET_CORE to
  show its not specific to ET_CORE.
- Link to v4: https://lore.kernel.org/r/20250111-elf-v4-0-b3841fa0dcd9@daynix.com

Changes in v4:
- s/powwerpc/powerpc/
- s/NT_INIT/nt_init/g s/NT_SIZE/nt_size/g
- Removed parentheses that have little value.
- Fixed the code alignment in get_cpu_elf_notes_size().
- Link to v3: https://lore.kernel.org/r/20250107-elf-v3-0-99cb505b1ab2@daynix.com

Changes in v3:
- Added patch "s390/crash: Use note name macros".
- Changed to interleave note name and type macros.
- Described NN_ and NT_ macros.
- Link to v2: https://lore.kernel.org/r/20250104-elf-v2-0-77dc2e06db4e@daynix.com

Changes in v2:
- Added a macro definition for each note type instead of trying to
  describe in a comment.
- Link to v1: https://lore.kernel.org/r/20241225-elf-v1-1-79e940350d50@daynix.com

---
Akihiko Odaki (6):
      elf: Define note name macros
      binfmt_elf: Use note name macros
      powerpc: Use note name macros
      crash: Use note name macros
      s390/crash: Use note name macros
      crash: Remove KEXEC_CORE_NOTE_NAME

 arch/powerpc/kernel/fadump.c               |  2 +-
 arch/powerpc/platforms/powernv/opal-core.c |  8 +--
 arch/s390/kernel/crash_dump.c              | 62 ++++++++-------------
 fs/binfmt_elf.c                            | 21 ++++---
 fs/binfmt_elf_fdpic.c                      |  8 +--
 fs/proc/kcore.c                            | 12 ++--
 include/linux/kexec.h                      |  2 -
 include/linux/vmcore_info.h                |  3 +-
 include/uapi/linux/elf.h                   | 89 ++++++++++++++++++++++++++++--
 kernel/crash_core.c                        |  2 +-
 10 files changed, 134 insertions(+), 75 deletions(-)
---
base-commit: a32e14f8aef69b42826cf0998b068a43d486a9e9
change-id: 20241210-elf-b80ea3949c39

Best regards,
-- 
Akihiko Odaki <akihiko.odaki@daynix.com>

[PATCH v5 1/6] elf: Define note name macros

[Akihiko Odaki]

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 to remove their duplicate definitions of note names.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Acked-by: Baoquan He <bhe@redhat.com>
---
 include/uapi/linux/elf.h | 89 +++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 84 insertions(+), 5 deletions(-)

diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h
index b44069d29cec..592507aa9b3a 100644
--- a/include/uapi/linux/elf.h
+++ b/include/uapi/linux/elf.h
@@ -368,101 +368,180 @@ typedef struct elf64_shdr {
 #define ELF_OSABI ELFOSABI_NONE
 #endif
 
+/* Note definitions: NN_ defines names. NT_ defines types. */
+
+#define NN_GNU_PROPERTY_TYPE_0	"GNU"
+#define NT_GNU_PROPERTY_TYPE_0	5
+
 /*
  * 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 NN_PRSTATUS	"CORE"
 #define NT_PRSTATUS	1
+#define NN_PRFPREG	"CORE"
 #define NT_PRFPREG	2
+#define NN_PRPSINFO	"CORE"
 #define NT_PRPSINFO	3
+#define NN_TASKSTRUCT	"CORE"
 #define NT_TASKSTRUCT	4
+#define NN_AUXV		"CORE"
 #define NT_AUXV		6
 /*
  * Note to userspace developers: size of NT_SIGINFO note may increase
  * in the future to accomodate more fields, don't assume it is fixed!
  */
+#define NN_SIGINFO      "CORE"
 #define NT_SIGINFO      0x53494749
+#define NN_FILE         "CORE"
 #define NT_FILE         0x46494c45
+#define NN_PRXFPREG     "LINUX"
 #define NT_PRXFPREG     0x46e62b7f      /* copied from gdb5.1/include/elf/common.h */
+#define NN_PPC_VMX	"LINUX"
 #define NT_PPC_VMX	0x100		/* PowerPC Altivec/VMX registers */
+#define NN_PPC_SPE	"LINUX"
 #define NT_PPC_SPE	0x101		/* PowerPC SPE/EVR registers */
+#define NN_PPC_VSX	"LINUX"
 #define NT_PPC_VSX	0x102		/* PowerPC VSX registers */
+#define NN_PPC_TAR	"LINUX"
 #define NT_PPC_TAR	0x103		/* Target Address Register */
+#define NN_PPC_PPR	"LINUX"
 #define NT_PPC_PPR	0x104		/* Program Priority Register */
+#define NN_PPC_DSCR	"LINUX"
 #define NT_PPC_DSCR	0x105		/* Data Stream Control Register */
+#define NN_PPC_EBB	"LINUX"
 #define NT_PPC_EBB	0x106		/* Event Based Branch Registers */
+#define NN_PPC_PMU	"LINUX"
 #define NT_PPC_PMU	0x107		/* Performance Monitor Registers */
+#define NN_PPC_TM_CGPR	"LINUX"
 #define NT_PPC_TM_CGPR	0x108		/* TM checkpointed GPR Registers */
+#define NN_PPC_TM_CFPR	"LINUX"
 #define NT_PPC_TM_CFPR	0x109		/* TM checkpointed FPR Registers */
+#define NN_PPC_TM_CVMX	"LINUX"
 #define NT_PPC_TM_CVMX	0x10a		/* TM checkpointed VMX Registers */
+#define NN_PPC_TM_CVSX	"LINUX"
 #define NT_PPC_TM_CVSX	0x10b		/* TM checkpointed VSX Registers */
+#define NN_PPC_TM_SPR	"LINUX"
 #define NT_PPC_TM_SPR	0x10c		/* TM Special Purpose Registers */
+#define NN_PPC_TM_CTAR	"LINUX"
 #define NT_PPC_TM_CTAR	0x10d		/* TM checkpointed Target Address Register */
+#define NN_PPC_TM_CPPR	"LINUX"
 #define NT_PPC_TM_CPPR	0x10e		/* TM checkpointed Program Priority Register */
+#define NN_PPC_TM_CDSCR	"LINUX"
 #define NT_PPC_TM_CDSCR	0x10f		/* TM checkpointed Data Stream Control Register */
+#define NN_PPC_PKEY	"LINUX"
 #define NT_PPC_PKEY	0x110		/* Memory Protection Keys registers */
+#define NN_PPC_DEXCR	"LINUX"
 #define NT_PPC_DEXCR	0x111		/* PowerPC DEXCR registers */
+#define NN_PPC_HASHKEYR	"LINUX"
 #define NT_PPC_HASHKEYR	0x112		/* PowerPC HASHKEYR register */
+#define NN_386_TLS	"LINUX"
 #define NT_386_TLS	0x200		/* i386 TLS slots (struct user_desc) */
+#define NN_386_IOPERM	"LINUX"
 #define NT_386_IOPERM	0x201		/* x86 io permission bitmap (1=deny) */
+#define NN_X86_XSTATE	"LINUX"
 #define NT_X86_XSTATE	0x202		/* x86 extended state using xsave */
 /* Old binutils treats 0x203 as a CET state */
+#define NN_X86_SHSTK	"LINUX"
 #define NT_X86_SHSTK	0x204		/* x86 SHSTK state */
+#define NN_X86_XSAVE_LAYOUT	"LINUX"
 #define NT_X86_XSAVE_LAYOUT	0x205	/* XSAVE layout description */
+#define NN_S390_HIGH_GPRS	"LINUX"
 #define NT_S390_HIGH_GPRS	0x300	/* s390 upper register halves */
+#define NN_S390_TIMER	"LINUX"
 #define NT_S390_TIMER	0x301		/* s390 timer register */
+#define NN_S390_TODCMP	"LINUX"
 #define NT_S390_TODCMP	0x302		/* s390 TOD clock comparator register */
+#define NN_S390_TODPREG	"LINUX"
 #define NT_S390_TODPREG	0x303		/* s390 TOD programmable register */
+#define NN_S390_CTRS	"LINUX"
 #define NT_S390_CTRS	0x304		/* s390 control registers */
+#define NN_S390_PREFIX	"LINUX"
 #define NT_S390_PREFIX	0x305		/* s390 prefix register */
+#define NN_S390_LAST_BREAK	"LINUX"
 #define NT_S390_LAST_BREAK	0x306	/* s390 breaking event address */
+#define NN_S390_SYSTEM_CALL	"LINUX"
 #define NT_S390_SYSTEM_CALL	0x307	/* s390 system call restart data */
+#define NN_S390_TDB	"LINUX"
 #define NT_S390_TDB	0x308		/* s390 transaction diagnostic block */
+#define NN_S390_VXRS_LOW	"LINUX"
 #define NT_S390_VXRS_LOW	0x309	/* s390 vector registers 0-15 upper half */
+#define NN_S390_VXRS_HIGH	"LINUX"
 #define NT_S390_VXRS_HIGH	0x30a	/* s390 vector registers 16-31 */
+#define NN_S390_GS_CB	"LINUX"
 #define NT_S390_GS_CB	0x30b		/* s390 guarded storage registers */
+#define NN_S390_GS_BC	"LINUX"
 #define NT_S390_GS_BC	0x30c		/* s390 guarded storage broadcast control block */
+#define NN_S390_RI_CB	"LINUX"
 #define NT_S390_RI_CB	0x30d		/* s390 runtime instrumentation */
+#define NN_S390_PV_CPU_DATA	"LINUX"
 #define NT_S390_PV_CPU_DATA	0x30e	/* s390 protvirt cpu dump data */
+#define NN_ARM_VFP	"LINUX"
 #define NT_ARM_VFP	0x400		/* ARM VFP/NEON registers */
+#define NN_ARM_TLS	"LINUX"
 #define NT_ARM_TLS	0x401		/* ARM TLS register */
+#define NN_ARM_HW_BREAK	"LINUX"
 #define NT_ARM_HW_BREAK	0x402		/* ARM hardware breakpoint registers */
+#define NN_ARM_HW_WATCH	"LINUX"
 #define NT_ARM_HW_WATCH	0x403		/* ARM hardware watchpoint registers */
+#define NN_ARM_SYSTEM_CALL	"LINUX"
 #define NT_ARM_SYSTEM_CALL	0x404	/* ARM system call number */
+#define NN_ARM_SVE	"LINUX"
 #define NT_ARM_SVE	0x405		/* ARM Scalable Vector Extension registers */
+#define NN_ARM_PAC_MASK		"LINUX"
 #define NT_ARM_PAC_MASK		0x406	/* ARM pointer authentication code masks */
+#define NN_ARM_PACA_KEYS	"LINUX"
 #define NT_ARM_PACA_KEYS	0x407	/* ARM pointer authentication address keys */
+#define NN_ARM_PACG_KEYS	"LINUX"
 #define NT_ARM_PACG_KEYS	0x408	/* ARM pointer authentication generic key */
+#define NN_ARM_TAGGED_ADDR_CTRL	"LINUX"
 #define NT_ARM_TAGGED_ADDR_CTRL	0x409	/* arm64 tagged address control (prctl()) */
+#define NN_ARM_PAC_ENABLED_KEYS	"LINUX"
 #define NT_ARM_PAC_ENABLED_KEYS	0x40a	/* arm64 ptr auth enabled keys (prctl()) */
+#define NN_ARM_SSVE	"LINUX"
 #define NT_ARM_SSVE	0x40b		/* ARM Streaming SVE registers */
+#define NN_ARM_ZA	"LINUX"
 #define NT_ARM_ZA	0x40c		/* ARM SME ZA registers */
+#define NN_ARM_ZT	"LINUX"
 #define NT_ARM_ZT	0x40d		/* ARM SME ZT registers */
+#define NN_ARM_FPMR	"LINUX"
 #define NT_ARM_FPMR	0x40e		/* ARM floating point mode register */
+#define NN_ARM_POE	"LINUX"
 #define NT_ARM_POE	0x40f		/* ARM POE registers */
+#define NN_ARM_GCS	"LINUX"
 #define NT_ARM_GCS	0x410		/* ARM GCS state */
+#define NN_ARC_V2	"LINUX"
 #define NT_ARC_V2	0x600		/* ARCv2 accumulator/extra registers */
+#define NN_VMCOREDD	"LINUX"
 #define NT_VMCOREDD	0x700		/* Vmcore Device Dump Note */
+#define NN_MIPS_DSP	"LINUX"
 #define NT_MIPS_DSP	0x800		/* MIPS DSP ASE registers */
+#define NN_MIPS_FP_MODE	"LINUX"
 #define NT_MIPS_FP_MODE	0x801		/* MIPS floating-point mode */
+#define NN_MIPS_MSA	"LINUX"
 #define NT_MIPS_MSA	0x802		/* MIPS SIMD registers */
+#define NN_RISCV_CSR	"LINUX"
 #define NT_RISCV_CSR	0x900		/* RISC-V Control and Status Registers */
+#define NN_RISCV_VECTOR	"LINUX"
 #define NT_RISCV_VECTOR	0x901		/* RISC-V vector registers */
+#define NN_RISCV_TAGGED_ADDR_CTRL "LINUX"
 #define NT_RISCV_TAGGED_ADDR_CTRL 0x902	/* RISC-V tagged address control (prctl()) */
+#define NN_LOONGARCH_CPUCFG	"LINUX"
 #define NT_LOONGARCH_CPUCFG	0xa00	/* LoongArch CPU config registers */
+#define NN_LOONGARCH_CSR	"LINUX"
 #define NT_LOONGARCH_CSR	0xa01	/* LoongArch control and status registers */
+#define NN_LOONGARCH_LSX	"LINUX"
 #define NT_LOONGARCH_LSX	0xa02	/* LoongArch Loongson SIMD Extension registers */
+#define NN_LOONGARCH_LASX	"LINUX"
 #define NT_LOONGARCH_LASX	0xa03	/* LoongArch Loongson Advanced SIMD Extension registers */
+#define NN_LOONGARCH_LBT	"LINUX"
 #define NT_LOONGARCH_LBT	0xa04	/* LoongArch Loongson Binary Translation registers */
+#define NN_LOONGARCH_HW_BREAK	"LINUX"
 #define NT_LOONGARCH_HW_BREAK	0xa05   /* LoongArch hardware breakpoint registers */
+#define NN_LOONGARCH_HW_WATCH	"LINUX"
 #define NT_LOONGARCH_HW_WATCH	0xa06   /* LoongArch hardware watchpoint registers */
 
-/* Note types with note name "GNU" */
-#define NT_GNU_PROPERTY_TYPE_0	5
-
 /* Note header in a PT_NOTE section */
 typedef struct elf32_note {
   Elf32_Word	n_namesz;	/* Name size */

-- 
2.47.1

[PATCH v5 2/6] binfmt_elf: Use note name macros

[Akihiko Odaki]

Use note name macros to match with the userspace's expectation.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Acked-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
---
 fs/binfmt_elf.c       | 21 ++++++++++-----------
 fs/binfmt_elf_fdpic.c |  8 ++++----
 2 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 106f0e8af177..5b4a92e5e508 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -762,8 +762,7 @@ static int parse_elf_property(const char *data, size_t *off, size_t datasz,
 }
 
 #define NOTE_DATA_SZ SZ_1K
-#define GNU_PROPERTY_TYPE_0_NAME "GNU"
-#define NOTE_NAME_SZ (sizeof(GNU_PROPERTY_TYPE_0_NAME))
+#define NOTE_NAME_SZ (sizeof(NN_GNU_PROPERTY_TYPE_0))
 
 static int parse_elf_properties(struct file *f, const struct elf_phdr *phdr,
 				struct arch_elf_state *arch)
@@ -800,7 +799,7 @@ static int parse_elf_properties(struct file *f, const struct elf_phdr *phdr,
 	if (note.nhdr.n_type != NT_GNU_PROPERTY_TYPE_0 ||
 	    note.nhdr.n_namesz != NOTE_NAME_SZ ||
 	    strncmp(note.data + sizeof(note.nhdr),
-		    GNU_PROPERTY_TYPE_0_NAME, n - sizeof(note.nhdr)))
+		    NN_GNU_PROPERTY_TYPE_0, n - sizeof(note.nhdr)))
 		return -ENOEXEC;
 
 	off = round_up(sizeof(note.nhdr) + NOTE_NAME_SZ,
@@ -1603,14 +1602,14 @@ static void fill_auxv_note(struct memelfnote *note, struct mm_struct *mm)
 	do
 		i += 2;
 	while (auxv[i - 2] != AT_NULL);
-	fill_note(note, "CORE", NT_AUXV, i * sizeof(elf_addr_t), auxv);
+	fill_note(note, NN_AUXV, NT_AUXV, i * sizeof(elf_addr_t), auxv);
 }
 
 static void fill_siginfo_note(struct memelfnote *note, user_siginfo_t *csigdata,
 		const kernel_siginfo_t *siginfo)
 {
 	copy_siginfo_to_external(csigdata, siginfo);
-	fill_note(note, "CORE", NT_SIGINFO, sizeof(*csigdata), csigdata);
+	fill_note(note, NN_SIGINFO, NT_SIGINFO, sizeof(*csigdata), csigdata);
 }
 
 /*
@@ -1706,7 +1705,7 @@ static int fill_files_note(struct memelfnote *note, struct coredump_params *cprm
 	}
 
 	size = name_curpos - (char *)data;
-	fill_note(note, "CORE", NT_FILE, size, data);
+	fill_note(note, NN_FILE, NT_FILE, size, data);
 	return 0;
 }
 
@@ -1767,7 +1766,7 @@ static int fill_thread_core_info(struct elf_thread_core_info *t,
 	regset_get(t->task, &view->regsets[0],
 		   sizeof(t->prstatus.pr_reg), &t->prstatus.pr_reg);
 
-	fill_note(&t->notes[0], "CORE", NT_PRSTATUS,
+	fill_note(&t->notes[0], NN_PRSTATUS, NT_PRSTATUS,
 		  PRSTATUS_SIZE, &t->prstatus);
 	info->size += notesize(&t->notes[0]);
 
@@ -1801,7 +1800,7 @@ static int fill_thread_core_info(struct elf_thread_core_info *t,
 		if (is_fpreg)
 			SET_PR_FPVALID(&t->prstatus);
 
-		fill_note(&t->notes[note_iter], is_fpreg ? "CORE" : "LINUX",
+		fill_note(&t->notes[note_iter], is_fpreg ? NN_PRFPREG : "LINUX",
 			  note_type, ret, data);
 
 		info->size += notesize(&t->notes[note_iter]);
@@ -1821,7 +1820,7 @@ static int fill_thread_core_info(struct elf_thread_core_info *t,
 	fill_prstatus(&t->prstatus.common, p, signr);
 	elf_core_copy_task_regs(p, &t->prstatus.pr_reg);
 
-	fill_note(&t->notes[0], "CORE", NT_PRSTATUS, sizeof(t->prstatus),
+	fill_note(&t->notes[0], NN_PRSTATUS, NT_PRSTATUS, sizeof(t->prstatus),
 		  &(t->prstatus));
 	info->size += notesize(&t->notes[0]);
 
@@ -1832,7 +1831,7 @@ static int fill_thread_core_info(struct elf_thread_core_info *t,
 	}
 
 	t->prstatus.pr_fpvalid = 1;
-	fill_note(&t->notes[1], "CORE", NT_PRFPREG, sizeof(*fpu), fpu);
+	fill_note(&t->notes[1], NN_PRFPREG, NT_PRFPREG, sizeof(*fpu), fpu);
 	info->size += notesize(&t->notes[1]);
 
 	return 1;
@@ -1852,7 +1851,7 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
 	psinfo = kmalloc(sizeof(*psinfo), GFP_KERNEL);
 	if (!psinfo)
 		return 0;
-	fill_note(&info->psinfo, "CORE", NT_PRPSINFO, sizeof(*psinfo), psinfo);
+	fill_note(&info->psinfo, NN_PRPSINFO, NT_PRPSINFO, sizeof(*psinfo), psinfo);
 
 #ifdef CORE_DUMP_USE_REGSET
 	view = task_user_regset_view(dump_task);
diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index f1a7c4875c4a..96bd9d2f23d7 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -1397,7 +1397,7 @@ static struct elf_thread_status *elf_dump_thread_status(long signr, struct task_
 	regset_get(p, &view->regsets[0],
 		   sizeof(t->prstatus.pr_reg), &t->prstatus.pr_reg);
 
-	fill_note(&t->notes[0], "CORE", NT_PRSTATUS, sizeof(t->prstatus),
+	fill_note(&t->notes[0], NN_PRSTATUS, NT_PRSTATUS, sizeof(t->prstatus),
 		  &t->prstatus);
 	t->num_notes++;
 	*sz += notesize(&t->notes[0]);
@@ -1415,7 +1415,7 @@ static struct elf_thread_status *elf_dump_thread_status(long signr, struct task_
 	}
 
 	if (t->prstatus.pr_fpvalid) {
-		fill_note(&t->notes[1], "CORE", NT_PRFPREG, sizeof(t->fpu),
+		fill_note(&t->notes[1], NN_PRFPREG, NT_PRFPREG, sizeof(t->fpu),
 			  &t->fpu);
 		t->num_notes++;
 		*sz += notesize(&t->notes[1]);
@@ -1530,7 +1530,7 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
 	 */
 
 	fill_psinfo(psinfo, current->group_leader, current->mm);
-	fill_note(&psinfo_note, "CORE", NT_PRPSINFO, sizeof(*psinfo), psinfo);
+	fill_note(&psinfo_note, NN_PRPSINFO, NT_PRPSINFO, sizeof(*psinfo), psinfo);
 	thread_status_size += notesize(&psinfo_note);
 
 	auxv = (elf_addr_t *) current->mm->saved_auxv;
@@ -1538,7 +1538,7 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
 	do
 		i += 2;
 	while (auxv[i - 2] != AT_NULL);
-	fill_note(&auxv_note, "CORE", NT_AUXV, i * sizeof(elf_addr_t), auxv);
+	fill_note(&auxv_note, NN_AUXV, NT_AUXV, i * sizeof(elf_addr_t), auxv);
 	thread_status_size += notesize(&auxv_note);
 
 	offset = sizeof(*elf);				/* ELF header */

-- 
2.47.1

[PATCH v5 3/6] powerpc: Use note name macros

[Akihiko Odaki]

Use note name macros to match with the userspace's expectation.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Acked-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
---
 arch/powerpc/kernel/fadump.c               | 2 +-
 arch/powerpc/platforms/powernv/opal-core.c | 8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index 4b371c738213..d44349fe8e2b 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -751,7 +751,7 @@ u32 *__init fadump_regs_to_elf_notes(u32 *buf, struct pt_regs *regs)
 	 * prstatus.pr_pid = ????
 	 */
 	elf_core_copy_regs(&prstatus.pr_reg, regs);
-	buf = append_elf_note(buf, CRASH_CORE_NOTE_NAME, NT_PRSTATUS,
+	buf = append_elf_note(buf, NN_PRSTATUS, NT_PRSTATUS,
 			      &prstatus, sizeof(prstatus));
 	return buf;
 }
diff --git a/arch/powerpc/platforms/powernv/opal-core.c b/arch/powerpc/platforms/powernv/opal-core.c
index c9a9b759cc92..a379ff86c120 100644
--- a/arch/powerpc/platforms/powernv/opal-core.c
+++ b/arch/powerpc/platforms/powernv/opal-core.c
@@ -149,7 +149,7 @@ static Elf64_Word *__init auxv_to_elf64_notes(Elf64_Word *buf,
 	/* end of vector */
 	bufp[idx++] = cpu_to_be64(AT_NULL);
 
-	buf = append_elf64_note(buf, CRASH_CORE_NOTE_NAME, NT_AUXV,
+	buf = append_elf64_note(buf, NN_AUXV, NT_AUXV,
 				oc_conf->auxv_buf, AUXV_DESC_SZ);
 	return buf;
 }
@@ -252,7 +252,7 @@ static Elf64_Word * __init opalcore_append_cpu_notes(Elf64_Word *buf)
 	 * crashing CPU's prstatus.
 	 */
 	first_cpu_note = buf;
-	buf = append_elf64_note(buf, CRASH_CORE_NOTE_NAME, NT_PRSTATUS,
+	buf = append_elf64_note(buf, NN_PRSTATUS, NT_PRSTATUS,
 				&prstatus, sizeof(prstatus));
 
 	for (i = 0; i < oc_conf->num_cpus; i++, bufp += size_per_thread) {
@@ -279,7 +279,7 @@ static Elf64_Word * __init opalcore_append_cpu_notes(Elf64_Word *buf)
 		fill_prstatus(&prstatus, thread_pir, &regs);
 
 		if (thread_pir != oc_conf->crashing_cpu) {
-			buf = append_elf64_note(buf, CRASH_CORE_NOTE_NAME,
+			buf = append_elf64_note(buf, NN_PRSTATUS,
 						NT_PRSTATUS, &prstatus,
 						sizeof(prstatus));
 		} else {
@@ -287,7 +287,7 @@ static Elf64_Word * __init opalcore_append_cpu_notes(Elf64_Word *buf)
 			 * Add crashing CPU as the first NT_PRSTATUS note for
 			 * GDB to process the core file appropriately.
 			 */
-			append_elf64_note(first_cpu_note, CRASH_CORE_NOTE_NAME,
+			append_elf64_note(first_cpu_note, NN_PRSTATUS,
 					  NT_PRSTATUS, &prstatus,
 					  sizeof(prstatus));
 		}

-- 
2.47.1

[PATCH v5 4/6] crash: Use note name macros

[Akihiko Odaki]

Use note name macros to match with the userspace's expectation.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Acked-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
---
 fs/proc/kcore.c             | 12 ++++++------
 include/linux/vmcore_info.h |  2 +-
 kernel/crash_core.c         |  2 +-
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index e376f48c4b8b..e5612313b8b4 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -34,8 +34,6 @@
 #include <asm/sections.h>
 #include "internal.h"
 
-#define CORE_STR "CORE"
-
 #ifndef ELF_CORE_EFLAGS
 #define ELF_CORE_EFLAGS	0
 #endif
@@ -119,7 +117,9 @@ static size_t get_kcore_size(int *nphdr, size_t *phdrs_len, size_t *notes_len,
 
 	*phdrs_len = *nphdr * sizeof(struct elf_phdr);
 	*notes_len = (4 * sizeof(struct elf_note) +
-		      3 * ALIGN(sizeof(CORE_STR), 4) +
+		      ALIGN(sizeof(NN_PRSTATUS), 4) +
+		      ALIGN(sizeof(NN_PRPSINFO), 4) +
+		      ALIGN(sizeof(NN_TASKSTRUCT), 4) +
 		      VMCOREINFO_NOTE_NAME_BYTES +
 		      ALIGN(sizeof(struct elf_prstatus), 4) +
 		      ALIGN(sizeof(struct elf_prpsinfo), 4) +
@@ -444,11 +444,11 @@ static ssize_t read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter)
 			goto out;
 		}
 
-		append_kcore_note(notes, &i, CORE_STR, NT_PRSTATUS, &prstatus,
+		append_kcore_note(notes, &i, NN_PRSTATUS, NT_PRSTATUS, &prstatus,
 				  sizeof(prstatus));
-		append_kcore_note(notes, &i, CORE_STR, NT_PRPSINFO, &prpsinfo,
+		append_kcore_note(notes, &i, NN_PRPSINFO, NT_PRPSINFO, &prpsinfo,
 				  sizeof(prpsinfo));
-		append_kcore_note(notes, &i, CORE_STR, NT_TASKSTRUCT, current,
+		append_kcore_note(notes, &i, NN_TASKSTRUCT, NT_TASKSTRUCT, current,
 				  arch_task_struct_size);
 		/*
 		 * vmcoreinfo_size is mostly constant after init time, but it
diff --git a/include/linux/vmcore_info.h b/include/linux/vmcore_info.h
index e1dec1a6a749..1672801fd98c 100644
--- a/include/linux/vmcore_info.h
+++ b/include/linux/vmcore_info.h
@@ -8,7 +8,7 @@
 
 #define CRASH_CORE_NOTE_NAME	   "CORE"
 #define CRASH_CORE_NOTE_HEAD_BYTES ALIGN(sizeof(struct elf_note), 4)
-#define CRASH_CORE_NOTE_NAME_BYTES ALIGN(sizeof(CRASH_CORE_NOTE_NAME), 4)
+#define CRASH_CORE_NOTE_NAME_BYTES ALIGN(sizeof(NN_PRSTATUS), 4)
 #define CRASH_CORE_NOTE_DESC_BYTES ALIGN(sizeof(struct elf_prstatus), 4)
 
 /*
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 078fe5bc5a74..335b8425dd4b 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -436,7 +436,7 @@ void crash_save_cpu(struct pt_regs *regs, int cpu)
 	memset(&prstatus, 0, sizeof(prstatus));
 	prstatus.common.pr_pid = current->pid;
 	elf_core_copy_regs(&prstatus.pr_reg, regs);
-	buf = append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS,
+	buf = append_elf_note(buf, NN_PRSTATUS, NT_PRSTATUS,
 			      &prstatus, sizeof(prstatus));
 	final_note(buf);
 }

-- 
2.47.1

[PATCH v5 5/6] s390/crash: Use note name macros

[Akihiko Odaki]

Use note name macros to match with the userspace's expectation.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
---
 arch/s390/kernel/crash_dump.c | 62 ++++++++++++++++---------------------------
 1 file changed, 23 insertions(+), 39 deletions(-)

diff --git a/arch/s390/kernel/crash_dump.c b/arch/s390/kernel/crash_dump.c
index cd0c93a8fb8b..022f4f198edf 100644
--- a/arch/s390/kernel/crash_dump.c
+++ b/arch/s390/kernel/crash_dump.c
@@ -248,15 +248,6 @@ bool is_kdump_kernel(void)
 }
 EXPORT_SYMBOL_GPL(is_kdump_kernel);
 
-static const char *nt_name(Elf64_Word type)
-{
-	const char *name = "LINUX";
-
-	if (type == NT_PRPSINFO || type == NT_PRSTATUS || type == NT_PRFPREG)
-		name = KEXEC_CORE_NOTE_NAME;
-	return name;
-}
-
 /*
  * Initialize ELF note
  */
@@ -281,10 +272,8 @@ static void *nt_init_name(void *buf, Elf64_Word type, void *desc, int d_len,
 	return PTR_ADD(buf, len);
 }
 
-static inline void *nt_init(void *buf, Elf64_Word type, void *desc, int d_len)
-{
-	return nt_init_name(buf, type, desc, d_len, nt_name(type));
-}
+#define nt_init(buf, type, desc) \
+	nt_init_name(buf, NT_ ## type, &(desc), sizeof(desc), NN_ ## type)
 
 /*
  * Calculate the size of ELF note
@@ -300,10 +289,7 @@ static size_t nt_size_name(int d_len, const char *name)
 	return size;
 }
 
-static inline size_t nt_size(Elf64_Word type, int d_len)
-{
-	return nt_size_name(d_len, nt_name(type));
-}
+#define nt_size(type, desc) nt_size_name(sizeof(desc), NN_ ## type)
 
 /*
  * Fill ELF notes for one CPU with save area registers
@@ -324,18 +310,16 @@ static void *fill_cpu_elf_notes(void *ptr, int cpu, struct save_area *sa)
 	memcpy(&nt_fpregset.fpc, &sa->fpc, sizeof(sa->fpc));
 	memcpy(&nt_fpregset.fprs, &sa->fprs, sizeof(sa->fprs));
 	/* Create ELF notes for the CPU */
-	ptr = nt_init(ptr, NT_PRSTATUS, &nt_prstatus, sizeof(nt_prstatus));
-	ptr = nt_init(ptr, NT_PRFPREG, &nt_fpregset, sizeof(nt_fpregset));
-	ptr = nt_init(ptr, NT_S390_TIMER, &sa->timer, sizeof(sa->timer));
-	ptr = nt_init(ptr, NT_S390_TODCMP, &sa->todcmp, sizeof(sa->todcmp));
-	ptr = nt_init(ptr, NT_S390_TODPREG, &sa->todpreg, sizeof(sa->todpreg));
-	ptr = nt_init(ptr, NT_S390_CTRS, &sa->ctrs, sizeof(sa->ctrs));
-	ptr = nt_init(ptr, NT_S390_PREFIX, &sa->prefix, sizeof(sa->prefix));
+	ptr = nt_init(ptr, PRSTATUS, nt_prstatus);
+	ptr = nt_init(ptr, PRFPREG, nt_fpregset);
+	ptr = nt_init(ptr, S390_TIMER, sa->timer);
+	ptr = nt_init(ptr, S390_TODCMP, sa->todcmp);
+	ptr = nt_init(ptr, S390_TODPREG, sa->todpreg);
+	ptr = nt_init(ptr, S390_CTRS, sa->ctrs);
+	ptr = nt_init(ptr, S390_PREFIX, sa->prefix);
 	if (cpu_has_vx()) {
-		ptr = nt_init(ptr, NT_S390_VXRS_HIGH,
-			      &sa->vxrs_high, sizeof(sa->vxrs_high));
-		ptr = nt_init(ptr, NT_S390_VXRS_LOW,
-			      &sa->vxrs_low, sizeof(sa->vxrs_low));
+		ptr = nt_init(ptr, S390_VXRS_HIGH, sa->vxrs_high);
+		ptr = nt_init(ptr, S390_VXRS_LOW, sa->vxrs_low);
 	}
 	return ptr;
 }
@@ -348,16 +332,16 @@ static size_t get_cpu_elf_notes_size(void)
 	struct save_area *sa = NULL;
 	size_t size;
 
-	size =	nt_size(NT_PRSTATUS, sizeof(struct elf_prstatus));
-	size +=  nt_size(NT_PRFPREG, sizeof(elf_fpregset_t));
-	size +=  nt_size(NT_S390_TIMER, sizeof(sa->timer));
-	size +=  nt_size(NT_S390_TODCMP, sizeof(sa->todcmp));
-	size +=  nt_size(NT_S390_TODPREG, sizeof(sa->todpreg));
-	size +=  nt_size(NT_S390_CTRS, sizeof(sa->ctrs));
-	size +=  nt_size(NT_S390_PREFIX, sizeof(sa->prefix));
+	size =	nt_size(PRSTATUS, struct elf_prstatus);
+	size += nt_size(PRFPREG, elf_fpregset_t);
+	size += nt_size(S390_TIMER, sa->timer);
+	size += nt_size(S390_TODCMP, sa->todcmp);
+	size += nt_size(S390_TODPREG, sa->todpreg);
+	size += nt_size(S390_CTRS, sa->ctrs);
+	size += nt_size(S390_PREFIX, sa->prefix);
 	if (cpu_has_vx()) {
-		size += nt_size(NT_S390_VXRS_HIGH, sizeof(sa->vxrs_high));
-		size += nt_size(NT_S390_VXRS_LOW, sizeof(sa->vxrs_low));
+		size += nt_size(S390_VXRS_HIGH, sa->vxrs_high);
+		size += nt_size(S390_VXRS_LOW, sa->vxrs_low);
 	}
 
 	return size;
@@ -373,7 +357,7 @@ static void *nt_prpsinfo(void *ptr)
 	memset(&prpsinfo, 0, sizeof(prpsinfo));
 	prpsinfo.pr_sname = 'R';
 	strcpy(prpsinfo.pr_fname, "vmlinux");
-	return nt_init(ptr, NT_PRPSINFO, &prpsinfo, sizeof(prpsinfo));
+	return nt_init(ptr, PRPSINFO, prpsinfo);
 }
 
 /*
@@ -589,7 +573,7 @@ static size_t get_elfcorehdr_size(int phdr_count)
 	/* PT_NOTES */
 	size += sizeof(Elf64_Phdr);
 	/* nt_prpsinfo */
-	size += nt_size(NT_PRPSINFO, sizeof(struct elf_prpsinfo));
+	size += nt_size(PRPSINFO, struct elf_prpsinfo);
 	/* regsets */
 	size += get_cpu_cnt() * get_cpu_elf_notes_size();
 	/* nt_vmcoreinfo */

-- 
2.47.1

[PATCH v5 6/6] crash: Remove KEXEC_CORE_NOTE_NAME

[Akihiko Odaki]

KEXEC_CORE_NOTE_NAME is no longer used.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Acked-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
---
 include/linux/kexec.h       | 2 --
 include/linux/vmcore_info.h | 1 -
 2 files changed, 3 deletions(-)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index f0e9f8eda7a3..c840431eadda 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -68,8 +68,6 @@ extern note_buf_t __percpu *crash_notes;
 #define KEXEC_CRASH_MEM_ALIGN PAGE_SIZE
 #endif
 
-#define KEXEC_CORE_NOTE_NAME	CRASH_CORE_NOTE_NAME
-
 /*
  * This structure is used to hold the arguments that are used when loading
  * kernel binaries.
diff --git a/include/linux/vmcore_info.h b/include/linux/vmcore_info.h
index 1672801fd98c..37e003ae5262 100644
--- a/include/linux/vmcore_info.h
+++ b/include/linux/vmcore_info.h
@@ -6,7 +6,6 @@
 #include <linux/elfcore.h>
 #include <linux/elf.h>
 
-#define CRASH_CORE_NOTE_NAME	   "CORE"
 #define CRASH_CORE_NOTE_HEAD_BYTES ALIGN(sizeof(struct elf_note), 4)
 #define CRASH_CORE_NOTE_NAME_BYTES ALIGN(sizeof(NN_PRSTATUS), 4)
 #define CRASH_CORE_NOTE_DESC_BYTES ALIGN(sizeof(struct elf_prstatus), 4)

-- 
2.47.1

Re: [PATCH v5 1/6] elf: Define note name macros

[Dave Martin]

Hi,

On Wed, Jan 15, 2025 at 02:47:58PM +0900, 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 to remove their duplicate definitions of note names.
> 
> Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
> Acked-by: Baoquan He <bhe@redhat.com>
> ---
>  include/uapi/linux/elf.h | 89 +++++++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 84 insertions(+), 5 deletions(-)
> 
> diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h
> index b44069d29cec..592507aa9b3a 100644
> --- a/include/uapi/linux/elf.h
> +++ b/include/uapi/linux/elf.h
> @@ -368,101 +368,180 @@ typedef struct elf64_shdr {
>  #define ELF_OSABI ELFOSABI_NONE
>  #endif
>  
> +/* Note definitions: NN_ defines names. NT_ defines types. */
> +
> +#define NN_GNU_PROPERTY_TYPE_0	"GNU"
> +#define NT_GNU_PROPERTY_TYPE_0	5
> +

I guess this also works as a neutral way of saying that
NT_GNU_PROPERTY_TYPE_0 isn't _specifically_ for coredumps.

I would worry that moving this block is going to generate unwanted
context noise with other patches that may be in flight and add new
NT_ definitions.

But (a) changing the comments will cause that anyway, and
(b) if there are any new NT_ definitions in flight, we want people to
notice the conflict and add the accompanying NN_ definition.

So, perhaps context noise is not such a bad thing in this instance.

[...]

> +#define NN_LOONGARCH_HW_WATCH	"LINUX"
>  #define NT_LOONGARCH_HW_WATCH	0xa06   /* LoongArch hardware watchpoint registers */
>  
> -/* Note types with note name "GNU" */
> -#define NT_GNU_PROPERTY_TYPE_0	5
> -
>  /* Note header in a PT_NOTE section */
>  typedef struct elf32_note {
>    Elf32_Word	n_namesz;	/* Name size */

Reviewed-by: Dave Martin <Dave.Martin@arm.com>

Cheers
---Dave

Re: [PATCH v5 0/6] elf: Define note name macros

[Kees Cook]

On Wed, 15 Jan 2025 14:47:57 +0900, 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".
> 
> [...]

I rebased this for changes introduced by commit
680e029fd62f ("proc/kcore: don't walk list on every read")

Applied to for-next/execve, thanks!

[1/6] elf: Define note name macros
      https://git.kernel.org/kees/c/7da8e4ad4df0
[2/6] binfmt_elf: Use note name macros
      https://git.kernel.org/kees/c/2fc4947bbd91
[3/6] powerpc: Use note name macros
      https://git.kernel.org/kees/c/609c8b309156
[4/6] crash: Use note name macros
      https://git.kernel.org/kees/c/0de47f28ec84
[5/6] s390/crash: Use note name macros
      https://git.kernel.org/kees/c/d4a760fb77fd
[6/6] crash: Remove KEXEC_CORE_NOTE_NAME
      https://git.kernel.org/kees/c/7e620b56d958

Take care,

-- 
Kees Cook