Commit fd2ab2f6 authored by Masahiro Yamada's avatar Masahiro Yamada
Browse files

scripts/kallsyms: fix offset overflow of kallsyms_relative_base 

Since commit 5e5c4fa7 ("scripts/kallsyms: shrink table before
sorting it"), kallsyms_relative_base can be larger than _text, which
causes overflow when building the 32-bit kernel.

https://lkml.org/lkml/2019/12/7/156



This is because _text is, unless --all-symbols is specified, now
trimmed from the symbol table before record_relative_base() is called.

Handle the offset signedness also for kallsyms_relative_base. Introduce
a new helper, output_address(), to reduce the code duplication.

Fixes: 5e5c4fa7 ("scripts/kallsyms: shrink table before sorting it")
Reported-by: default avatarOlof Johansson <olof@lixom.net>
Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
parent c8f3dea9

scripts/kallsyms.c

+18 −20
Original line number Diff line number Diff line
@@ -310,6 +310,15 @@ static void output_label(const char *label) 
	printf("%s:\n", label);

}



/* Provide proper symbols relocatability by their '_text' relativeness. */

static void output_address(unsigned long long addr)

{

	if (_text <= addr)

		printf("\tPTR\t_text + %#llx\n", addr - _text);

	else

		printf("\tPTR\t_text - %#llx\n", _text - addr);

}



/* uncompress a compressed symbol. When this function is called, the best table

 * might still be compressed itself, so the function needs to be recursive */

static int expand_symbol(const unsigned char *data, int len, char *result)
@@ -360,19 +369,6 @@ static void write_src(void) 


	printf("\t.section .rodata, \"a\"\n");



	/* Provide proper symbols relocatability by their relativeness

	 * to a fixed anchor point in the runtime image, either '_text'

	 * for absolute address tables, in which case the linker will

	 * emit the final addresses at build time. Otherwise, use the

	 * offset relative to the lowest value encountered of all relative

	 * symbols, and emit non-relocatable fixed offsets that will be fixed

	 * up at runtime.

	 *

	 * The symbol names cannot be used to construct normal symbol

	 * references as the list of symbols contains symbols that are

	 * declared static and are private to their .o files.  This prevents

	 * .tmp_kallsyms.o or any other object from referencing them.

	 */

	if (!base_relative)

		output_label("kallsyms_addresses");

	else
@@ -380,6 +376,13 @@ static void write_src(void) 


	for (i = 0; i < table_cnt; i++) {

		if (base_relative) {

			/*

			 * Use the offset relative to the lowest value

			 * encountered of all relative symbols, and emit

			 * non-relocatable fixed offsets that will be fixed

			 * up at runtime.

			 */



			long long offset;

			int overflow;
@@ -402,12 +405,7 @@ static void write_src(void) 
			}

			printf("\t.long\t%#x\n", (int)offset);

		} else if (!symbol_absolute(&table[i])) {

			if (_text <= table[i].addr)

				printf("\tPTR\t_text + %#llx\n",

					table[i].addr - _text);

			else

				printf("\tPTR\t_text - %#llx\n",

					_text - table[i].addr);

			output_address(table[i].addr);

		} else {

			printf("\tPTR\t%#llx\n", table[i].addr);

		}
@@ -416,7 +414,7 @@ static void write_src(void) 


	if (base_relative) {

		output_label("kallsyms_relative_base");

		printf("\tPTR\t_text - %#llx\n", _text - relative_base);

		output_address(relative_base);

		printf("\n");

	}

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