From: Josh Poimboeuf <jpoim...@kernel.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 <jpoim...@kernel.org> Co-developed-by: Steven Rostedt (Google) <rost...@goodmis.org> Signed-off-by: Steven Rostedt (Google) <rost...@goodmis.org> --- Changes since v12: https://lore.kernel.org/20250701005451.055982...@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
