Author: emaste Date: Tue Jun 4 13:07:10 2019 New Revision: 348611 URL: https://svnweb.freebsd.org/changeset/base/348611
Log: 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. Submitted by: Ali Mashtizadeh <ali_mashtizadeh.com> MFC after: 2 weeks Relnotes: Yes Event: Waterloo Hackathon 2019 Differential Revision: https://reviews.freebsd.org/D20326 Modified: head/sys/conf/ldscript.amd64 head/sys/conf/ldscript.arm head/sys/conf/ldscript.arm64 head/sys/conf/ldscript.i386 head/sys/conf/ldscript.mips head/sys/conf/ldscript.mips.cfe head/sys/conf/ldscript.mips.mips64 head/sys/conf/ldscript.mips.octeon1 head/sys/conf/ldscript.powerpc head/sys/conf/ldscript.powerpc64 head/sys/conf/ldscript.powerpcspe head/sys/conf/ldscript.riscv head/sys/conf/ldscript.sparc64 head/sys/kern/kern_mib.c Modified: head/sys/conf/ldscript.amd64 ============================================================================== --- head/sys/conf/ldscript.amd64 Tue Jun 4 13:00:49 2019 (r348610) +++ head/sys/conf/ldscript.amd64 Tue Jun 4 13:07:10 2019 (r348611) @@ -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: head/sys/conf/ldscript.arm ============================================================================== --- head/sys/conf/ldscript.arm Tue Jun 4 13:00:49 2019 (r348610) +++ head/sys/conf/ldscript.arm Tue Jun 4 13:07:10 2019 (r348611) @@ -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: head/sys/conf/ldscript.arm64 ============================================================================== --- head/sys/conf/ldscript.arm64 Tue Jun 4 13:00:49 2019 (r348610) +++ head/sys/conf/ldscript.arm64 Tue Jun 4 13:07:10 2019 (r348611) @@ -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: head/sys/conf/ldscript.i386 ============================================================================== --- head/sys/conf/ldscript.i386 Tue Jun 4 13:00:49 2019 (r348610) +++ head/sys/conf/ldscript.i386 Tue Jun 4 13:07:10 2019 (r348611) @@ -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: head/sys/conf/ldscript.mips ============================================================================== --- head/sys/conf/ldscript.mips Tue Jun 4 13:00:49 2019 (r348610) +++ head/sys/conf/ldscript.mips Tue Jun 4 13:07:10 2019 (r348611) @@ -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: head/sys/conf/ldscript.mips.cfe ============================================================================== --- head/sys/conf/ldscript.mips.cfe Tue Jun 4 13:00:49 2019 (r348610) +++ head/sys/conf/ldscript.mips.cfe Tue Jun 4 13:07:10 2019 (r348611) @@ -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: head/sys/conf/ldscript.mips.mips64 ============================================================================== --- head/sys/conf/ldscript.mips.mips64 Tue Jun 4 13:00:49 2019 (r348610) +++ head/sys/conf/ldscript.mips.mips64 Tue Jun 4 13:07:10 2019 (r348611) @@ -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: head/sys/conf/ldscript.mips.octeon1 ============================================================================== --- head/sys/conf/ldscript.mips.octeon1 Tue Jun 4 13:00:49 2019 (r348610) +++ head/sys/conf/ldscript.mips.octeon1 Tue Jun 4 13:07:10 2019 (r348611) @@ -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: head/sys/conf/ldscript.powerpc ============================================================================== --- head/sys/conf/ldscript.powerpc Tue Jun 4 13:00:49 2019 (r348610) +++ head/sys/conf/ldscript.powerpc Tue Jun 4 13:07:10 2019 (r348611) @@ -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: head/sys/conf/ldscript.powerpc64 ============================================================================== --- head/sys/conf/ldscript.powerpc64 Tue Jun 4 13:00:49 2019 (r348610) +++ head/sys/conf/ldscript.powerpc64 Tue Jun 4 13:07:10 2019 (r348611) @@ -46,6 +46,11 @@ 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: head/sys/conf/ldscript.powerpcspe ============================================================================== --- head/sys/conf/ldscript.powerpcspe Tue Jun 4 13:00:49 2019 (r348610) +++ head/sys/conf/ldscript.powerpcspe Tue Jun 4 13:07:10 2019 (r348611) @@ -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: head/sys/conf/ldscript.riscv ============================================================================== --- head/sys/conf/ldscript.riscv Tue Jun 4 13:00:49 2019 (r348610) +++ head/sys/conf/ldscript.riscv Tue Jun 4 13:07:10 2019 (r348611) @@ -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: head/sys/conf/ldscript.sparc64 ============================================================================== --- head/sys/conf/ldscript.sparc64 Tue Jun 4 13:00:49 2019 (r348610) +++ head/sys/conf/ldscript.sparc64 Tue Jun 4 13:07:10 2019 (r348611) @@ -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: head/sys/kern/kern_mib.c ============================================================================== --- head/sys/kern/kern_mib.c Tue Jun 4 13:00:49 2019 (r348610) +++ head/sys/kern/kern_mib.c Tue Jun 4 13:07:10 2019 (r348611) @@ -481,6 +481,54 @@ 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 _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
