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authorJosh Poimboeuf <jpoimboe@kernel.org>2023-06-05 19:12:22 +0300
committerJosh Poimboeuf <jpoimboe@kernel.org>2023-06-07 20:03:12 +0300
commita9da8247627eefc73f909bf945031a5431a53993 (patch)
tree7f4ad803471dc7823978c654e452b69c2908dbf1 /arch/x86/include/asm/unwind_hints.h
parent1e4b619185e83e54aca617cf5070c64a88fe936b (diff)
downloadlinux-a9da8247627eefc73f909bf945031a5431a53993.tar.xz
drm/vmwgfx: Add unwind hints around RBP clobber
VMware high-bandwidth hypercalls take the RBP register as input. This breaks basic frame pointer convention, as RBP should never be clobbered. So frame pointer unwinding is broken for the instructions surrounding the hypercalls. Fortunately this doesn't break live patching with CONFIG_FRAME_POINTER, as it only unwinds from blocking tasks, and stack traces from preempted tasks are already marked unreliable anyway. However, for live patching with ORC, this could actually be a theoretical problem if vmw_port_hb_{in,out}() were still compiled with a frame pointer due to having an aligned stack. In practice that hasn't seemed to be an issue since the objtool warnings have only been seen with CONFIG_FRAME_POINTER. Add unwind hint annotations to tell the ORC unwinder to mark stack traces as unreliable. Fixes the following warnings: vmlinux.o: warning: objtool: vmw_port_hb_in+0x1df: return with modified stack frame vmlinux.o: warning: objtool: vmw_port_hb_out+0x1dd: return with modified stack frame Fixes: 89da76fde68d ("drm/vmwgfx: Add VMWare host messaging capability") Reported-by: kernel test robot <lkp@intel.com> Link: https://lore.kernel.org/oe-kbuild-all/202305160135.97q0Elax-lkp@intel.com/ Link: https://lore.kernel.org/r/4c795f2d87bc0391cf6543bcb224fa540b55ce4b.1685981486.git.jpoimboe@kernel.org Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Diffstat (limited to 'arch/x86/include/asm/unwind_hints.h')
-rw-r--r--arch/x86/include/asm/unwind_hints.h9
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/x86/include/asm/unwind_hints.h b/arch/x86/include/asm/unwind_hints.h
index 01cb9692b160..85cc57cb6539 100644
--- a/arch/x86/include/asm/unwind_hints.h
+++ b/arch/x86/include/asm/unwind_hints.h
@@ -76,9 +76,18 @@
#else
+#define UNWIND_HINT_UNDEFINED \
+ UNWIND_HINT(UNWIND_HINT_TYPE_UNDEFINED, 0, 0, 0)
+
#define UNWIND_HINT_FUNC \
UNWIND_HINT(UNWIND_HINT_TYPE_FUNC, ORC_REG_SP, 8, 0)
+#define UNWIND_HINT_SAVE \
+ UNWIND_HINT(UNWIND_HINT_TYPE_SAVE, 0, 0, 0)
+
+#define UNWIND_HINT_RESTORE \
+ UNWIND_HINT(UNWIND_HINT_TYPE_RESTORE, 0, 0, 0)
+
#endif /* __ASSEMBLY__ */
#endif /* _ASM_X86_UNWIND_HINTS_H */