Commit da0f622b authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt (Google)
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ftrace: Check against is_kernel_text() instead of kaslr_offset() 

As kaslr_offset() is architecture dependent and also may not be defined by
all architectures, when zeroing out unused weak functions, do not check
against kaslr_offset(), but instead check if the address is within the
kernel text sections. If KASLR added a shift to the zeroed out function,
it would still not be located in the kernel text. This is a more robust
way to test if the text is valid or not.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: "Arnd Bergmann" <arnd@arndb.de>
Link: https://lore.kernel.org/20250225182054.471759017@goodmis.org


Fixes: ef378c3b ("scripts/sorttable: Zero out weak functions in mcount_loc table")
Reported-by: default avatarNathan Chancellor <nathan@kernel.org>
Reported-by: default avatarMark Brown <broonie@kernel.org>
Tested-by: default avatarNathan Chancellor <nathan@kernel.org>
Closes: https://lore.kernel.org/all/20250224180805.GA1536711@ax162/
Closes: https://lore.kernel.org/all/5225b07b-a9b2-4558-9d5f-aa60b19f6317@sirena.org.uk/


Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 6eeca746

kernel/trace/ftrace.c

+12 −5
Original line number Diff line number Diff line
@@ -7004,7 +7004,6 @@ static int ftrace_process_locs(struct module *mod, 
	unsigned long count;

	unsigned long *p;

	unsigned long addr;

	unsigned long kaslr;

	unsigned long flags = 0; /* Shut up gcc */

	unsigned long pages;

	int ret = -ENOMEM;
@@ -7056,9 +7055,6 @@ static int ftrace_process_locs(struct module *mod, 
		ftrace_pages->next = start_pg;

	}



	/* For zeroed locations that were shifted for core kernel */

	kaslr = !mod ? kaslr_offset() : 0;



	p = start;

	pg = start_pg;

	while (p < end) {
@@ -7072,7 +7068,18 @@ static int ftrace_process_locs(struct module *mod, 
		 * object files to satisfy alignments.

		 * Skip any NULL pointers.

		 */

		if (!addr || addr == kaslr) {

		if (!addr) {

			skipped++;

			continue;

		}



		/*

		 * If this is core kernel, make sure the address is in core

		 * or inittext, as weak functions get zeroed and KASLR can

		 * move them to something other than zero. It just will not

		 * move it to an area where kernel text is.

		 */

		if (!mod && !(is_kernel_text(addr) || is_kernel_inittext(addr))) {

			skipped++;

			continue;

		}