From: Nick Desaulniers <ndesaulniers(a)google.com>
Basically, consider .text.{hot|unlikely|unknown}.* part of .text, too.
When compiling with profiling information (collected via PGO
instrumentations or AutoFDO sampling), Clang will separate code into
.text.hot, .text.unlikely, or .text.unknown sections based on profiling
information. After D79600 (clang-11), these sections will have a
trailing `.` suffix, ie. .text.hot., .text.unlikely., .text.unknown..
When using -ffunction-sections together with profiling infomation,
either explicitly (FGKASLR) or implicitly (LTO), code may be placed in
sections following the convention:
.text.hot.<foo>, .text.unlikely.<bar>, .text.unknown.<baz>
where <foo>, <bar>, and <baz> are functions. (This produces one section
per function; we generally try to merge these all back via linker script
so that we don't have 50k sections).
For the above cases, we need to teach our linker scripts that such
sections might exist and that we'd explicitly like them grouped
together, otherwise we can wind up with code outside of the
_stext/_etext boundaries that might not be mapped properly for some
architectures, resulting in boot failures.
If the linker script is not told about possible input sections, then
where the section is placed as output is a heuristic-laiden mess that's
non-portable between linkers (ie. BFD and LLD), and has resulted in many
hard to debug bugs. Kees Cook is working on cleaning this up by adding
--orphan-handling=warn linker flag used in ARCH=powerpc to additional
architectures. In the case of linker scripts, borrowing from the Zen of
Python: explicit is better than implicit.
Also, ld.bfd's internal linker script considers .text.hot AND
.text.hot.* to be part of .text, as well as .text.unlikely and
.text.unlikely.*. I didn't see support for .text.unknown.*, and didn't
see Clang producing such code in our kernel builds, but I see code in
LLVM that can produce such section names if profiling information is
missing. That may point to a larger issue with generating or collecting
profiles, but I would much rather be safe and explicit than have to
debug yet another issue related to orphan section placement.
Reported-by: Jian Cai <jiancai(a)google.com>
Suggested-by: Fāng-ruì Sòng <maskray(a)google.com>
Tested-by: Luis Lozano <llozano(a)google.com>
Tested-by: Manoj Gupta <manojgupta(a)google.com>
Acked-by: Kees Cook <keescook(a)chromium.org>
Cc: stable(a)vger.kernel.org
Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=add44f8d5c5c0…
Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=1de778ed23ce7…
Link: https://reviews.llvm.org/D79600
Link: https://bugs.chromium.org/p/chromium/issues/detail?id=1084760
Debugged-by: Luis Lozano <llozano(a)google.com>
Signed-off-by: Nick Desaulniers <ndesaulniers(a)google.com>
Signed-off-by: Kees Cook <keescook(a)chromium.org>
---
include/asm-generic/vmlinux.lds.h | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 2593957f6e8b..af5211ca857c 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -561,7 +561,10 @@
*/
#define TEXT_TEXT \
ALIGN_FUNCTION(); \
- *(.text.hot TEXT_MAIN .text.fixup .text.unlikely) \
+ *(.text.hot .text.hot.*) \
+ *(TEXT_MAIN .text.fixup) \
+ *(.text.unlikely .text.unlikely.*) \
+ *(.text.unknown .text.unknown.*) \
NOINSTR_TEXT \
*(.text..refcount) \
*(.ref.text) \
--
2.25.1
When the primary firmware node pointer is removed from a
device (set to NULL) the secondary firmware node pointer,
when it exists, is made the primary node for the device.
However, the secondary firmware node pointer of the original
primary firmware node is never cleared (set to NULL).
To avoid situation where the secondary firmware node pointer
is pointing to a non-existing object, clearing it properly
when the primary node is removed from a device in
set_primary_fwnode().
Fixes: 97badf873ab6 ("device property: Make it possible to use secondary firmware nodes")
Cc: stable(a)vger.kernel.org
Signed-off-by: Heikki Krogerus <heikki.krogerus(a)linux.intel.com>
---
drivers/base/core.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/drivers/base/core.c b/drivers/base/core.c
index ac1046a382bc0..f6f620aa94086 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -4264,9 +4264,9 @@ static inline bool fwnode_is_primary(struct fwnode_handle *fwnode)
*/
void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
{
- if (fwnode) {
- struct fwnode_handle *fn = dev->fwnode;
+ struct fwnode_handle *fn = dev->fwnode;
+ if (fwnode) {
if (fwnode_is_primary(fn))
fn = fn->secondary;
@@ -4276,8 +4276,12 @@ void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
}
dev->fwnode = fwnode;
} else {
- dev->fwnode = fwnode_is_primary(dev->fwnode) ?
- dev->fwnode->secondary : NULL;
+ if (fwnode_is_primary(fn)) {
+ dev->fwnode = fn->secondary;
+ fn->secondary = NULL;
+ } else {
+ dev->fwnode = NULL;
+ }
}
}
EXPORT_SYMBOL_GPL(set_primary_fwnode);
--
2.28.0