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authorJosh Poimboeuf <jpoimboe@kernel.org>2025-08-27 15:36:45 -0400
committerPeter Zijlstra <peterz@infradead.org>2025-10-29 10:29:58 +0100
commit49cf34c0815f93fb2ea3ab5cfbac1124bd9b45d0 (patch)
tree7d992773237a9eea5f25ac04a547c04b45c8de31
parentc79dd946e370af3537edb854f210cba3a94b4516 (diff)
unwind_user/x86: Enable frame pointer unwinding on x86
Use ARCH_INIT_USER_FP_FRAME to describe how frame pointers are unwound on x86, and enable CONFIG_HAVE_UNWIND_USER_FP accordingly so the unwind_user interfaces can be used. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://patch.msgid.link/20250827193828.347397433@kernel.org
-rw-r--r--arch/x86/Kconfig1
-rw-r--r--arch/x86/include/asm/unwind_user.h25
2 files changed, 26 insertions, 0 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index fa3b616af03a..5cf1afc0a974 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -297,6 +297,7 @@ config X86
select HAVE_SYSCALL_TRACEPOINTS
select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
select HAVE_UNSTABLE_SCHED_CLOCK
+ select HAVE_UNWIND_USER_FP if X86_64
select HAVE_USER_RETURN_NOTIFIER
select HAVE_GENERIC_VDSO
select VDSO_GETRANDOM if X86_64
diff --git a/arch/x86/include/asm/unwind_user.h b/arch/x86/include/asm/unwind_user.h
new file mode 100644
index 000000000000..b166e102d444
--- /dev/null
+++ b/arch/x86/include/asm/unwind_user.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_UNWIND_USER_H
+#define _ASM_X86_UNWIND_USER_H
+
+#include <asm/ptrace.h>
+
+#define ARCH_INIT_USER_FP_FRAME(ws) \
+ .cfa_off = 2*(ws), \
+ .ra_off = -1*(ws), \
+ .fp_off = -2*(ws), \
+ .use_fp = true,
+
+static inline int unwind_user_word_size(struct pt_regs *regs)
+{
+ /* We can't unwind VM86 stacks */
+ if (regs->flags & X86_VM_MASK)
+ return 0;
+#ifdef CONFIG_X86_64
+ if (!user_64bit_mode(regs))
+ return sizeof(int);
+#endif
+ return sizeof(long);
+}
+
+#endif /* _ASM_X86_UNWIND_USER_H */