Author: jhb
Date: Fri May 8 14:48:45 2020
New Revision: 360814
URL: https://svnweb.freebsd.org/changeset/base/360814
Log:
MFC 348611: Expose the kernel's build-ID through sysctl
After our migration (of certain architectures) to lld the kernel is built
with a unique build-ID. Make it available via a sysctl and uname(1) to
allow the user to identify their running kernel.
Modified:
stable/12/sys/conf/ldscript.amd64
stable/12/sys/conf/ldscript.arm
stable/12/sys/conf/ldscript.arm64
stable/12/sys/conf/ldscript.i386
stable/12/sys/conf/ldscript.mips
stable/12/sys/conf/ldscript.mips.cfe
stable/12/sys/conf/ldscript.mips.mips64
stable/12/sys/conf/ldscript.mips.octeon1
stable/12/sys/conf/ldscript.powerpc
stable/12/sys/conf/ldscript.powerpc64
stable/12/sys/conf/ldscript.powerpcspe
stable/12/sys/conf/ldscript.riscv
stable/12/sys/conf/ldscript.sparc64
stable/12/sys/kern/kern_mib.c
Directory Properties:
stable/12/ (props changed)
Modified: stable/12/sys/conf/ldscript.amd64
==============================================================================
--- stable/12/sys/conf/ldscript.amd64 Fri May 8 14:39:38 2020
(r360813)
+++ stable/12/sys/conf/ldscript.amd64 Fri May 8 14:48:45 2020
(r360814)
@@ -74,6 +74,11 @@ SECTIONS
PROVIDE (etext = .);
.rodata : { *(.rodata .rodata.* .gnu.linkonce.r.*) }
.rodata1 : { *(.rodata1) }
+ .note.gnu.build-id : {
+ PROVIDE (__build_id_start = .);
+ *(.note.gnu.build-id)
+ PROVIDE (__build_id_end = .);
+ }
.eh_frame_hdr : { *(.eh_frame_hdr) }
.eh_frame : ONLY_IF_RO { KEEP (*(.eh_frame)) }
.gcc_except_table : ONLY_IF_RO { *(.gcc_except_table .gcc_except_table.*) }
Modified: stable/12/sys/conf/ldscript.arm
==============================================================================
--- stable/12/sys/conf/ldscript.arm Fri May 8 14:39:38 2020
(r360813)
+++ stable/12/sys/conf/ldscript.arm Fri May 8 14:48:45 2020
(r360814)
@@ -27,6 +27,11 @@ SECTIONS
.gnu.version : { *(.gnu.version) }
.gnu.version_d : { *(.gnu.version_d) }
.gnu.version_r : { *(.gnu.version_r) }
+ .note.gnu.build-id : {
+ PROVIDE (__build_id_start = .);
+ *(.note.gnu.build-id)
+ PROVIDE (__build_id_end = .);
+ }
.rel.text :
{ *(.rel.text) *(.rel.gnu.linkonce.t*) }
.rela.text :
Modified: stable/12/sys/conf/ldscript.arm64
==============================================================================
--- stable/12/sys/conf/ldscript.arm64 Fri May 8 14:39:38 2020
(r360813)
+++ stable/12/sys/conf/ldscript.arm64 Fri May 8 14:48:45 2020
(r360814)
@@ -27,6 +27,11 @@ SECTIONS
.gnu.version : { *(.gnu.version) }
.gnu.version_d : { *(.gnu.version_d) }
.gnu.version_r : { *(.gnu.version_r) }
+ .note.gnu.build-id : {
+ PROVIDE (__build_id_start = .);
+ *(.note.gnu.build-id)
+ PROVIDE (__build_id_end = .);
+ }
.rel.text :
{ *(.rel.text) *(.rel.gnu.linkonce.t*) }
.rela.text :
Modified: stable/12/sys/conf/ldscript.i386
==============================================================================
--- stable/12/sys/conf/ldscript.i386 Fri May 8 14:39:38 2020
(r360813)
+++ stable/12/sys/conf/ldscript.i386 Fri May 8 14:48:45 2020
(r360814)
@@ -62,6 +62,11 @@ SECTIONS
PROVIDE (etext = .);
.rodata : { *(.rodata .rodata.* .gnu.linkonce.r.*) }
.rodata1 : { *(.rodata1) }
+ .note.gnu.build-id : {
+ PROVIDE (__build_id_start = .);
+ *(.note.gnu.build-id)
+ PROVIDE (__build_id_end = .);
+ }
.eh_frame_hdr : { *(.eh_frame_hdr) }
.eh_frame : ONLY_IF_RO { KEEP (*(.eh_frame)) }
.gcc_except_table : ONLY_IF_RO { *(.gcc_except_table .gcc_except_table.*) }
Modified: stable/12/sys/conf/ldscript.mips
==============================================================================
--- stable/12/sys/conf/ldscript.mips Fri May 8 14:39:38 2020
(r360813)
+++ stable/12/sys/conf/ldscript.mips Fri May 8 14:48:45 2020
(r360814)
@@ -63,6 +63,11 @@ SECTIONS
.gnu.version : { *(.gnu.version) }
.gnu.version_d : { *(.gnu.version_d) }
.gnu.version_r : { *(.gnu.version_r) }
+ .note.gnu.build-id : {
+ PROVIDE (__build_id_start = .);
+ *(.note.gnu.build-id)
+ PROVIDE (__build_id_end = .);
+ }
.rel.init : { *(.rel.init) }
.rela.init : { *(.rela.init) }
.rel.text :
Modified: stable/12/sys/conf/ldscript.mips.cfe
==============================================================================
--- stable/12/sys/conf/ldscript.mips.cfe Fri May 8 14:39:38 2020
(r360813)
+++ stable/12/sys/conf/ldscript.mips.cfe Fri May 8 14:48:45 2020
(r360814)
@@ -192,6 +192,11 @@ SECTIONS
PROVIDE (etext = .);
.rodata : { *(.rodata) *(.rodata.*) *(.gnu.linkonce.r.*) }
.rodata1 : { *(.rodata1) }
+ .note.gnu.build-id : {
+ PROVIDE (__build_id_start = .);
+ *(.note.gnu.build-id)
+ PROVIDE (__build_id_end = .);
+ }
.reginfo : { *(.reginfo) }
.sdata2 : { *(.sdata2) *(.sdata2.*) *(.gnu.linkonce.s2.*) }
.sbss2 : { *(.sbss2) *(.sbss2.*) *(.gnu.linkonce.sb2.*) }
Modified: stable/12/sys/conf/ldscript.mips.mips64
==============================================================================
--- stable/12/sys/conf/ldscript.mips.mips64 Fri May 8 14:39:38 2020
(r360813)
+++ stable/12/sys/conf/ldscript.mips.mips64 Fri May 8 14:48:45 2020
(r360814)
@@ -176,6 +176,11 @@ SECTIONS
PROVIDE (etext = .);
.rodata : { *(.rodata) *(.rodata.*) *(.gnu.linkonce.r.*) }
.rodata1 : { *(.rodata1) }
+ .note.gnu.build-id : {
+ PROVIDE (__build_id_start = .);
+ *(.note.gnu.build-id)
+ PROVIDE (__build_id_end = .);
+ }
.reginfo : { *(.reginfo) }
.sdata2 : { *(.sdata2) *(.sdata2.*) *(.gnu.linkonce.s2.*) }
.sbss2 : { *(.sbss2) *(.sbss2.*) *(.gnu.linkonce.sb2.*) }
Modified: stable/12/sys/conf/ldscript.mips.octeon1
==============================================================================
--- stable/12/sys/conf/ldscript.mips.octeon1 Fri May 8 14:39:38 2020
(r360813)
+++ stable/12/sys/conf/ldscript.mips.octeon1 Fri May 8 14:48:45 2020
(r360814)
@@ -23,6 +23,12 @@ SECTIONS {
*(.rodata)
. = ALIGN(32);
}
+
+ .note.gnu.build-id : {
+ PROVIDE (__build_id_start = .);
+ *(.note.gnu.build-id)
+ PROVIDE (__build_id_end = .);
+ }
.data : {
_rwdata = .;
Modified: stable/12/sys/conf/ldscript.powerpc
==============================================================================
--- stable/12/sys/conf/ldscript.powerpc Fri May 8 14:39:38 2020
(r360813)
+++ stable/12/sys/conf/ldscript.powerpc Fri May 8 14:48:45 2020
(r360814)
@@ -55,6 +55,11 @@ SECTIONS
.fini : { *(.fini) } =0
.rodata : { *(.rodata) *(.gnu.linkonce.r*) }
.rodata1 : { *(.rodata1) }
+ .note.gnu.build-id : {
+ PROVIDE (__build_id_start = .);
+ *(.note.gnu.build-id)
+ PROVIDE (__build_id_end = .);
+ }
.sdata2 : { *(.sdata2) }
.sbss2 : { *(.sbss2) }
/* Adjust the address for the data segment to the next page up. */
Modified: stable/12/sys/conf/ldscript.powerpc64
==============================================================================
--- stable/12/sys/conf/ldscript.powerpc64 Fri May 8 14:39:38 2020
(r360813)
+++ stable/12/sys/conf/ldscript.powerpc64 Fri May 8 14:48:45 2020
(r360814)
@@ -41,6 +41,11 @@ SECTIONS
.gnu.version : { *(.gnu.version) }
.gnu.version_d : { *(.gnu.version_d) }
.gnu.version_r : { *(.gnu.version_r) }
+ .note.gnu.build-id : {
+ PROVIDE (__build_id_start = .);
+ *(.note.gnu.build-id)
+ PROVIDE (__build_id_end = .);
+ }
.rela.text :
{ *(.rela.text) *(.rela.gnu.linkonce.t*) }
.rela.data :
Modified: stable/12/sys/conf/ldscript.powerpcspe
==============================================================================
--- stable/12/sys/conf/ldscript.powerpcspe Fri May 8 14:39:38 2020
(r360813)
+++ stable/12/sys/conf/ldscript.powerpcspe Fri May 8 14:48:45 2020
(r360814)
@@ -55,6 +55,11 @@ SECTIONS
.fini : { *(.fini) } =0
.rodata : { *(.rodata) *(.gnu.linkonce.r*) }
.rodata1 : { *(.rodata1) }
+ .note.gnu.build-id : {
+ PROVIDE (__build_id_start = .);
+ *(.note.gnu.build-id)
+ PROVIDE (__build_id_end = .);
+ }
.sdata2 : { *(.sdata2) }
.sbss2 : { *(.sbss2) }
/* Adjust the address for the data segment to the next page up. */
Modified: stable/12/sys/conf/ldscript.riscv
==============================================================================
--- stable/12/sys/conf/ldscript.riscv Fri May 8 14:39:38 2020
(r360813)
+++ stable/12/sys/conf/ldscript.riscv Fri May 8 14:48:45 2020
(r360814)
@@ -28,6 +28,11 @@ SECTIONS
.gnu.version : { *(.gnu.version) }
.gnu.version_d : { *(.gnu.version_d) }
.gnu.version_r : { *(.gnu.version_r) }
+ .note.gnu.build-id : {
+ PROVIDE (__build_id_start = .);
+ *(.note.gnu.build-id)
+ PROVIDE (__build_id_end = .);
+ }
.rel.text :
{ *(.rel.text) *(.rel.gnu.linkonce.t*) }
.rela.text :
Modified: stable/12/sys/conf/ldscript.sparc64
==============================================================================
--- stable/12/sys/conf/ldscript.sparc64 Fri May 8 14:39:38 2020
(r360813)
+++ stable/12/sys/conf/ldscript.sparc64 Fri May 8 14:48:45 2020
(r360814)
@@ -146,6 +146,11 @@ SECTIONS
PROVIDE (etext = .);
.rodata : { *(.rodata) *(.rodata.*) *(.gnu.linkonce.r.*) }
.rodata1 : { *(.rodata1) }
+ .note.gnu.build-id : {
+ PROVIDE (__build_id_start = .);
+ *(.note.gnu.build-id)
+ PROVIDE (__build_id_end = .);
+ }
.sdata2 : { *(.sdata2) *(.sdata2.*) *(.gnu.linkonce.s2.*) }
.sbss2 : { *(.sbss2) *(.sbss2.*) *(.gnu.linkonce.sb2.*) }
. = ALIGN(0x2000) + (. & (0x2000 - 1));
Modified: stable/12/sys/kern/kern_mib.c
==============================================================================
--- stable/12/sys/kern/kern_mib.c Fri May 8 14:39:38 2020
(r360813)
+++ stable/12/sys/kern/kern_mib.c Fri May 8 14:48:45 2020
(r360814)
@@ -491,6 +491,54 @@ SYSCTL_PROC(_kern, KERN_OSRELDATE, osreldate,
CTLTYPE_INT | CTLFLAG_CAPRD | CTLFLAG_RD | CTLFLAG_MPSAFE,
NULL, 0, sysctl_osreldate, "I", "Kernel release date");
+/*
+ * The build-id is copied from the ELF section .note.gnu.build-id. The linker
+ * script defines two variables to expose the beginning and end. LLVM
+ * currently uses a SHA-1 hash, but other formats can be supported by checking
+ * the length of the section.
+ */
+
+extern char __build_id_start[];
+extern char __build_id_end[];
+
+#define BUILD_ID_HEADER_LEN 0x10
+#define BUILD_ID_HASH_MAXLEN 0x14
+
+static int
+sysctl_build_id(SYSCTL_HANDLER_ARGS)
+{
+ uintptr_t sectionlen = (uintptr_t)(__build_id_end - __build_id_start);
+ int hashlen;
+ char buf[2*BUILD_ID_HASH_MAXLEN+1];
+
+ /*
+ * The ELF note section has a four byte length for the vendor name,
+ * four byte length for the value, and a four byte vendor specific
+ * type. The name for the build id is "GNU\0". We skip the first 16
+ * bytes to read the build hash. We will return the remaining bytes up
+ * to 20 (SHA-1) hash size. If the hash happens to be a custom number
+ * of bytes we will pad the value with zeros, as the section should be
+ * four byte aligned.
+ */
+ if (sectionlen <= BUILD_ID_HEADER_LEN ||
+ sectionlen > (BUILD_ID_HEADER_LEN + BUILD_ID_HASH_MAXLEN)) {
+ return (ENOENT);
+ }
+
+
+ hashlen = sectionlen - BUILD_ID_HEADER_LEN;
+ for (int i = 0; i < hashlen; i++) {
+ uint8_t c = __build_id_start[i+BUILD_ID_HEADER_LEN];
+ snprintf(&buf[2*i], 3, "%02x", c);
+ }
+
+ return (SYSCTL_OUT(req, buf, strlen(buf) + 1));
+}
+
+SYSCTL_PROC(_kern, OID_AUTO, build_id,
+ CTLTYPE_STRING | CTLFLAG_CAPRD | CTLFLAG_RD | CTLFLAG_MPSAFE,
+ NULL, 0, sysctl_build_id, "A", "Operating system build-id");
+
SYSCTL_NODE(_kern, OID_AUTO, features, CTLFLAG_RD, 0, "Kernel Features");
#ifdef COMPAT_FREEBSD4
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