svn commit: r348611 - in head/sys: conf kern

Ian Lepore ian at freebsd.org
Tue Jun 4 14:58:11 UTC 2019


On Tue, 2019-06-04 at 13:07 +0000, Ed Maste wrote:
> 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.
>   

Won't this impact WITH_REPRODUCIBLE_BUILD?

-- Ian

>   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	(r348
> 610)
> +++ head/sys/conf/ldscript.amd64	Tue Jun  4 13:07:10 2019	(r348
> 611)
> @@ -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	(r348
> 610)
> +++ head/sys/conf/ldscript.arm	Tue Jun  4 13:07:10 2019	(r348
> 611)
> @@ -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	(r348
> 610)
> +++ head/sys/conf/ldscript.arm64	Tue Jun  4 13:07:10 2019	(r348
> 611)
> @@ -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	(r348
> 610)
> +++ head/sys/conf/ldscript.i386	Tue Jun  4 13:07:10 2019	(r348
> 611)
> @@ -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	(r348
> 610)
> +++ head/sys/conf/ldscript.mips	Tue Jun  4 13:07:10 2019	(r348
> 611)
> @@ -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	(r348
> 610)
> +++ head/sys/conf/ldscript.mips.cfe	Tue Jun  4 13:07:10 2019	(r348
> 611)
> @@ -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	(r348
> 610)
> +++ head/sys/conf/ldscript.powerpc	Tue Jun  4 13:07:10 2019	(r348
> 611)
> @@ -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	(r348
> 610)
> +++ head/sys/conf/ldscript.powerpc64	Tue Jun  4 13:07:10 2019	(r348
> 611)
> @@ -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	(r348
> 610)
> +++ head/sys/conf/ldscript.powerpcspe	Tue Jun  4 13:07:10 2019	(r348
> 611)
> @@ -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	(r348
> 610)
> +++ head/sys/conf/ldscript.riscv	Tue Jun  4 13:07:10 2019	(r348
> 611)
> @@ -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	(r348
> 610)
> +++ head/sys/conf/ldscript.sparc64	Tue Jun  4 13:07:10 2019	(r348
> 611)
> @@ -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
> 



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