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ftrace: Check against is_kernel_text() instead of kaslr_offset()

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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: ef378c3b82 ("scripts/sorttable: Zero out weak functions in mcount_loc table")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Reported-by: Mark Brown <broonie@kernel.org>
Tested-by: Nathan 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: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt 2025-02-25 13:20:06 -05:00 committed by Steven Rostedt (Google)
parent 6eeca746fa
commit da0f622b34
1 changed files with 12 additions and 5 deletions
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17
kernel/trace/ftrace.c
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@ -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;
}