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authorJosh Poimboeuf <jpoimboe@kernel.org>2022-07-18 17:50:25 +0300
committerPeter Zijlstra <peterz@infradead.org>2022-07-20 20:24:53 +0300
commitefc72a665a61fd48c462f5248a9e3dc991398ddd (patch)
tree5d72b6dce6d4a86951a07659455d3ef508d07d89 /drivers/misc/lkdtm
parenteb23b5ef9131e6d65011de349a4d25ef1b3d4314 (diff)
downloadlinux-efc72a665a61fd48c462f5248a9e3dc991398ddd.tar.xz
lkdtm: Disable return thunks in rodata.c
The following warning was seen: WARNING: CPU: 0 PID: 0 at arch/x86/kernel/alternative.c:557 apply_returns (arch/x86/kernel/alternative.c:557 (discriminator 1)) Modules linked in: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.19.0-rc4-00008-gee88d363d156 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-debian-1.16.0-4 04/01/2014 RIP: 0010:apply_returns (arch/x86/kernel/alternative.c:557 (discriminator 1)) Code: ff ff 74 cb 48 83 c5 04 49 39 ee 0f 87 81 fe ff ff e9 22 ff ff ff 0f 0b 48 83 c5 04 49 39 ee 0f 87 6d fe ff ff e9 0e ff ff ff <0f> 0b 48 83 c5 04 49 39 ee 0f 87 59 fe ff ff e9 fa fe ff ff 48 89 The warning happened when apply_returns() failed to convert "JMP __x86_return_thunk" to RET. It was instead a JMP to nowhere, due to the thunk relocation not getting resolved. That rodata.o code is objcopy'd to .rodata, and later memcpy'd, so relocations don't work (and are apparently silently ignored). LKDTM is only used for testing, so the naked RET should be fine. So just disable return thunks for that file. While at it, disable objtool and KCSAN for the file. Fixes: 0b53c374b9ef ("x86/retpoline: Use -mfunction-return") Reported-by: kernel test robot <oliver.sang@intel.com> Debugged-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/lkml/Ys58BxHxoDZ7rfpr@xsang-OptiPlex-9020/
Diffstat (limited to 'drivers/misc/lkdtm')
-rw-r--r--drivers/misc/lkdtm/Makefile9
1 files changed, 6 insertions, 3 deletions
diff --git a/drivers/misc/lkdtm/Makefile b/drivers/misc/lkdtm/Makefile
index 2e0aa74ac185..95ef971b5e1c 100644
--- a/drivers/misc/lkdtm/Makefile
+++ b/drivers/misc/lkdtm/Makefile
@@ -13,10 +13,13 @@ lkdtm-$(CONFIG_LKDTM) += cfi.o
lkdtm-$(CONFIG_LKDTM) += fortify.o
lkdtm-$(CONFIG_PPC_64S_HASH_MMU) += powerpc.o
-KASAN_SANITIZE_rodata.o := n
KASAN_SANITIZE_stackleak.o := n
-KCOV_INSTRUMENT_rodata.o := n
-CFLAGS_REMOVE_rodata.o += $(CC_FLAGS_LTO)
+
+KASAN_SANITIZE_rodata.o := n
+KCSAN_SANITIZE_rodata.o := n
+KCOV_INSTRUMENT_rodata.o := n
+OBJECT_FILES_NON_STANDARD_rodata.o := y
+CFLAGS_REMOVE_rodata.o += $(CC_FLAGS_LTO) $(RETHUNK_CFLAGS)
OBJCOPYFLAGS :=
OBJCOPYFLAGS_rodata_objcopy.o := \