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Message-ID: <20250708012358.152451558@kernel.org>
Date: Mon, 07 Jul 2025 21:22:42 -0400
From: Steven Rostedt <rostedt@...nel.org>
To: linux-kernel@...r.kernel.org,
linux-trace-kernel@...r.kernel.org,
bpf@...r.kernel.org,
x86@...nel.org
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Josh Poimboeuf <jpoimboe@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>,
Jiri Olsa <jolsa@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Andrii Nakryiko <andrii@...nel.org>,
Indu Bhagat <indu.bhagat@...cle.com>,
"Jose E. Marchesi" <jemarch@....org>,
Beau Belgrave <beaub@...ux.microsoft.com>,
Jens Remus <jremus@...ux.ibm.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Jens Axboe <axboe@...nel.dk>,
Florian Weimer <fweimer@...hat.com>,
Sam James <sam@...too.org>
Subject: [PATCH v13 03/14] unwind_user: Add compat mode frame pointer support
From: Josh Poimboeuf <jpoimboe@...nel.org>
Add optional support for user space compat mode frame pointer unwinding.
If supported, the arch needs to enable CONFIG_HAVE_UNWIND_USER_COMPAT_FP
and define ARCH_INIT_USER_COMPAT_FP_FRAME.
Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
Co-developed-by: Steven Rostedt (Google) <rostedt@...dmis.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
Changes since v12: https://lore.kernel.org/20250701005451.055982038@goodmis.org
- With new alignment check, updated to handle compat mode.
arch/Kconfig | 4 +++
include/asm-generic/Kbuild | 1 +
include/asm-generic/unwind_user_types.h | 5 ++++
include/linux/unwind_user.h | 5 ++++
include/linux/unwind_user_types.h | 7 +++++
kernel/unwind/user.c | 34 +++++++++++++++++++++----
6 files changed, 51 insertions(+), 5 deletions(-)
create mode 100644 include/asm-generic/unwind_user_types.h
diff --git a/arch/Kconfig b/arch/Kconfig
index 8e3fd723bd74..2c41d3072910 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -442,6 +442,10 @@ config HAVE_UNWIND_USER_FP
bool
select UNWIND_USER
+config HAVE_UNWIND_USER_COMPAT_FP
+ bool
+ depends on HAVE_UNWIND_USER_FP
+
config HAVE_PERF_REGS
bool
help
diff --git a/include/asm-generic/Kbuild b/include/asm-generic/Kbuild
index 295c94a3ccc1..b797a2434396 100644
--- a/include/asm-generic/Kbuild
+++ b/include/asm-generic/Kbuild
@@ -60,6 +60,7 @@ mandatory-y += topology.h
mandatory-y += trace_clock.h
mandatory-y += uaccess.h
mandatory-y += unwind_user.h
+mandatory-y += unwind_user_types.h
mandatory-y += vermagic.h
mandatory-y += vga.h
mandatory-y += video.h
diff --git a/include/asm-generic/unwind_user_types.h b/include/asm-generic/unwind_user_types.h
new file mode 100644
index 000000000000..f568b82e52cd
--- /dev/null
+++ b/include/asm-generic/unwind_user_types.h
@@ -0,0 +1,5 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_GENERIC_UNWIND_USER_TYPES_H
+#define _ASM_GENERIC_UNWIND_USER_TYPES_H
+
+#endif /* _ASM_GENERIC_UNWIND_USER_TYPES_H */
diff --git a/include/linux/unwind_user.h b/include/linux/unwind_user.h
index 7f7282516bf5..834b643afd3a 100644
--- a/include/linux/unwind_user.h
+++ b/include/linux/unwind_user.h
@@ -9,6 +9,11 @@
#define ARCH_INIT_USER_FP_FRAME
#endif
+#ifndef ARCH_INIT_USER_COMPAT_FP_FRAME
+ #define ARCH_INIT_USER_COMPAT_FP_FRAME
+ #define in_compat_mode(regs) false
+#endif
+
int unwind_user(struct unwind_stacktrace *trace, unsigned int max_entries);
#endif /* _LINUX_UNWIND_USER_H */
diff --git a/include/linux/unwind_user_types.h b/include/linux/unwind_user_types.h
index 65bd070eb6b0..0b6563951ca4 100644
--- a/include/linux/unwind_user_types.h
+++ b/include/linux/unwind_user_types.h
@@ -3,10 +3,16 @@
#define _LINUX_UNWIND_USER_TYPES_H
#include <linux/types.h>
+#include <asm/unwind_user_types.h>
+
+#ifndef arch_unwind_user_state
+struct arch_unwind_user_state {};
+#endif
enum unwind_user_type {
UNWIND_USER_TYPE_NONE,
UNWIND_USER_TYPE_FP,
+ UNWIND_USER_TYPE_COMPAT_FP,
};
struct unwind_stacktrace {
@@ -25,6 +31,7 @@ struct unwind_user_state {
unsigned long ip;
unsigned long sp;
unsigned long fp;
+ struct arch_unwind_user_state arch;
enum unwind_user_type type;
bool done;
};
diff --git a/kernel/unwind/user.c b/kernel/unwind/user.c
index 62b3ef37d71b..03775191447c 100644
--- a/kernel/unwind/user.c
+++ b/kernel/unwind/user.c
@@ -12,6 +12,10 @@ static struct unwind_user_frame fp_frame = {
ARCH_INIT_USER_FP_FRAME
};
+static struct unwind_user_frame compat_fp_frame = {
+ ARCH_INIT_USER_COMPAT_FP_FRAME
+};
+
static inline bool fp_state(struct unwind_user_state *state)
{
return IS_ENABLED(CONFIG_HAVE_UNWIND_USER_FP) &&
@@ -21,6 +25,22 @@ static inline bool fp_state(struct unwind_user_state *state)
#define for_each_user_frame(state) \
for (unwind_user_start(state); !(state)->done; unwind_user_next(state))
+static inline bool compat_fp_state(struct unwind_user_state *state)
+{
+ return IS_ENABLED(CONFIG_HAVE_UNWIND_USER_COMPAT_FP) &&
+ state->type == UNWIND_USER_TYPE_COMPAT_FP;
+}
+
+#define unwind_get_user_long(to, from, state) \
+({ \
+ int __ret; \
+ if (compat_fp_state(state)) \
+ __ret = get_user(to, (u32 __user *)(from)); \
+ else \
+ __ret = get_user(to, (unsigned long __user *)(from)); \
+ __ret; \
+})
+
static int unwind_user_next(struct unwind_user_state *state)
{
struct unwind_user_frame *frame;
@@ -30,7 +50,9 @@ static int unwind_user_next(struct unwind_user_state *state)
if (state->done)
return -EINVAL;
- if (fp_state(state))
+ if (compat_fp_state(state))
+ frame = &compat_fp_frame;
+ else if (fp_state(state))
frame = &fp_frame;
else
goto done;
@@ -51,15 +73,15 @@ static int unwind_user_next(struct unwind_user_state *state)
goto done;
/* Make sure that the address is word aligned */
- shift = sizeof(long) == 4 ? 2 : 3;
+ shift = sizeof(long) == 4 || compat_fp_state(state) ? 2 : 3;
if ((cfa + frame->ra_off) & ((1 << shift) - 1))
goto done;
/* Find the Return Address (RA) */
- if (get_user(ra, (unsigned long *)(cfa + frame->ra_off)))
+ if (unwind_get_user_long(ra, cfa + frame->ra_off, state))
goto done;
- if (frame->fp_off && get_user(fp, (unsigned long __user *)(cfa + frame->fp_off)))
+ if (frame->fp_off && unwind_get_user_long(fp, cfa + frame->fp_off, state))
goto done;
state->ip = ra;
@@ -85,7 +107,9 @@ static int unwind_user_start(struct unwind_user_state *state)
return -EINVAL;
}
- if (IS_ENABLED(CONFIG_HAVE_UNWIND_USER_FP))
+ if (IS_ENABLED(CONFIG_HAVE_UNWIND_USER_COMPAT_FP) && in_compat_mode(regs))
+ state->type = UNWIND_USER_TYPE_COMPAT_FP;
+ else if (IS_ENABLED(CONFIG_HAVE_UNWIND_USER_FP))
state->type = UNWIND_USER_TYPE_FP;
else
state->type = UNWIND_USER_TYPE_NONE;
--
2.47.2
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