Handle ELF notes during program load.

kernel/elf.cpp

@@ -1,6 +1,6 @@
 /*******************************************************************************
 
-    Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2013.
+    Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2013, 2014.
 
     This file is part of Sortix.
 
@@ -31,6 +31,7 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include <sortix/elf-note.h>
 #include <sortix/mman.h>
 
 #include <sortix/kernel/kernel.h>
@@ -48,7 +49,8 @@ namespace ELF {
 //       headers may vary depending on the ELF header and that using a simple
 //       table indexation isn't enough.
 
-addr_t Construct32(Process* process, const uint8_t* file, size_t filelen)
+addr_t Construct32(Process* process, const uint8_t* file, size_t filelen,
+                   Auxiliary* aux)
 {
 	if ( filelen < sizeof(Header32) )
 		return 0;
@@ -88,6 +90,38 @@ addr_t Construct32(Process* process, const uint8_t* file, size_t filelen)
 	for ( uint16_t i = 0; i < numprogheaders; i++ )
 	{
 		const ProgramHeader32* pht = &(phtbl[i]);
+		if ( pht->type == PT_TLS )
+		{
+			aux->tls_file_offset = pht->offset;
+			aux->tls_file_size = pht->filesize;
+			aux->tls_mem_size = pht->memorysize;
+			aux->tls_mem_align = pht->align;
+			continue;
+		}
+		if ( pht->type == PT_NOTE )
+		{
+			uintptr_t notes_addr = (uintptr_t) file + pht->offset;
+			size_t notes_offset = 0;
+			while ( notes_offset < pht->filesize )
+			{
+				uintptr_t note = notes_addr + notes_offset;
+				uint32_t namesz = *(uint32_t*) (note + 0);
+				uint32_t descsz = *(uint32_t*) (note + 4);
+				uint32_t type = *(uint32_t*) (note + 8);
+				uint32_t namesz_aligned = -(-namesz & ~(4U - 1));
+				uint32_t descsz_aligned = -(-descsz & ~(4U - 1));
+				size_t note_size = 12 + namesz_aligned + descsz_aligned;
+				notes_offset += note_size;
+				const char* name = (const char*) (note + 12);
+				uintptr_t desc = note + 12 + namesz_aligned;
+				if ( strcmp(name, "Sortix") == 0 )
+				{
+					(void) desc;
+					(void) type;
+				}
+			}
+			continue;
+		}
 		if ( pht->type != PT_LOAD )
 			continue;
 		addr_t virtualaddr = pht->virtualaddr;
@@ -210,12 +244,14 @@ addr_t Construct32(Process* process, const uint8_t* file, size_t filelen)
 	return entry;
 }
 
-addr_t Construct64(Process* process, const uint8_t* file, size_t filelen)
+addr_t Construct64(Process* process, const uint8_t* file, size_t filelen,
+                   Auxiliary* aux)
 {
 #if !defined(__x86_64__)
 	(void) process;
 	(void) file;
 	(void) filelen;
+	(void) aux;
 	return errno = ENOEXEC, 0;
 #else
 	if ( filelen < sizeof(Header64) )
@@ -256,6 +292,38 @@ addr_t Construct64(Process* process, const uint8_t* file, size_t filelen)
 	for ( uint16_t i = 0; i < numprogheaders; i++ )
 	{
 		const ProgramHeader64* pht = &(phtbl[i]);
+		if ( pht->type == PT_TLS )
+		{
+			aux->tls_file_offset = pht->offset;
+			aux->tls_file_size = pht->filesize;
+			aux->tls_mem_size = pht->memorysize;
+			aux->tls_mem_align = pht->align;
+			continue;
+		}
+		if ( pht->type == PT_NOTE )
+		{
+			uintptr_t notes_addr = (uintptr_t) file + pht->offset;
+			size_t notes_offset = 0;
+			while ( notes_offset < pht->filesize )
+			{
+				uintptr_t note = notes_addr + notes_offset;
+				uint32_t namesz = *(uint32_t*) (note + 0);
+				uint32_t descsz = *(uint32_t*) (note + 4);
+				uint32_t type = *(uint32_t*) (note + 8);
+				uint32_t namesz_aligned = -(-namesz & ~(4U - 1));
+				uint32_t descsz_aligned = -(-descsz & ~(4U - 1));
+				size_t note_size = 12 + namesz_aligned + descsz_aligned;
+				notes_offset += note_size;
+				const char* name = (const char*) (note + 12);
+				uintptr_t desc = note + 12 + namesz_aligned;
+				if ( strcmp(name, "Sortix") == 0 )
+				{
+					(void) desc;
+					(void) type;
+				}
+			}
+			continue;
+		}
 		if ( pht->type != PT_LOAD )
 			continue;
 		addr_t virtualaddr = pht->virtualaddr;
@@ -379,7 +447,8 @@ addr_t Construct64(Process* process, const uint8_t* file, size_t filelen)
 #endif
 }
 
-addr_t Construct(Process* process, const void* file, size_t filelen)
+addr_t Construct(Process* process, const void* file, size_t filelen,
+                 Auxiliary* aux)
 {
 	if ( filelen < sizeof(Header) )
 		return errno = ENOEXEC, 0;
@@ -390,10 +459,12 @@ addr_t Construct(Process* process, const void* file, size_t filelen)
            header->magic[2] == 'L'  && header->magic[3] == 'F'  ) )
 		return errno = ENOEXEC, 0;
 
+	memset(aux, 0, sizeof(*aux));
+
 	switch ( header->fileclass )
 	{
-		case CLASS32: return Construct32(process, (const uint8_t*) file, filelen);
-		case CLASS64: return Construct64(process, (const uint8_t*) file, filelen);
+		case CLASS32: return Construct32(process, (const uint8_t*) file, filelen, aux);
+		case CLASS64: return Construct64(process, (const uint8_t*) file, filelen, aux);
 		default:
 			return 0;
 	}

kernel/elf.h

@@ -25,12 +25,23 @@
 #ifndef SORTIX_ELF_H
 #define SORTIX_ELF_H
 
+#include <stddef.h>
+#include <stdint.h>
+
 namespace Sortix {
 
 class Process;
 
 namespace ELF {
 
+struct Auxiliary
+{
+	size_t tls_file_offset;
+	size_t tls_file_size;
+	size_t tls_mem_size;
+	size_t tls_mem_align;
+};
+
 struct Header
 {
 	unsigned char magic[4];
@@ -159,6 +170,7 @@ const uint32_t PT_INTERP = 3;
 const uint32_t PT_NOTE = 4;
 const uint32_t PT_SHLIB = 5;
 const uint32_t PT_PHDR = 6;
+const uint32_t PT_TLS = 7;
 const uint32_t PT_LOPROC = 0x70000000;
 const uint32_t PT_HIPROC = 0x7FFFFFFF;
 
@@ -188,7 +200,8 @@ struct Symbol64
 
 // Reads the elf file into the current address space and returns the entry
 // address of the program, or 0 upon failure.
-addr_t Construct(Process* process, const void* file, size_t filelen);
+addr_t Construct(Process* process, const void* file, size_t filelen,
+                 Auxiliary* aux);
 
 } // namespace ELF
 } // namespace Sortix

kernel/include/sortix/elf-note.h

@@ -0,0 +1,34 @@
+/*******************************************************************************
+
+    Copyright(C) Jonas 'Sortie' Termansen 2014.
+
+    This file is part of Sortix.
+
+    Sortix is free software: you can redistribute it and/or modify it under the
+    terms of the GNU General Public License as published by the Free Software
+    Foundation, either version 3 of the License, or (at your option) any later
+    version.
+
+    Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
+    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+    FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+    details.
+
+    You should have received a copy of the GNU General Public License along with
+    Sortix. If not, see <http://www.gnu.org/licenses/>.
+
+    sortix/elf-note.h
+    Declares type constants for the Sortix ELF notes.
+
+*******************************************************************************/
+
+#ifndef INCLUDE_SORTIX_ELF_NOTE_H
+#define INCLUDE_SORTIX_ELF_NOTE_H
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+__END_DECLS
+
+#endif

kernel/process.cpp

@@ -747,7 +747,9 @@ int Process::Execute(const char* programname, const uint8_t* program,
 	if ( !programname_clone )
 		return -1;
 
-	addr_t entry = ELF::Construct(CurrentProcess(), program, programsize);
+	ELF::Auxiliary aux;
+
+	addr_t entry = ELF::Construct(CurrentProcess(), program, programsize, &aux);
 	if ( !entry ) { delete[] programname_clone; return -1; }
 
 	delete[] program_image_path;