| Message ID | 169139096244.324433.7237290521765120297.stgit@devnote2 (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | bpf: fprobe: rethook: Use ftrace_regs instead of pt_regs | expand |
On Mon, Aug 7, 2023 at 8:49 AM Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote: > > From: Masami Hiramatsu (Google) <mhiramat@kernel.org> > > Add ftrace_partial_regs() which converts the ftrace_regas to pt_regs. ftrace_regs* > If the architecture defines its own ftrace_regs, this copies partial > registers to pt_regs and returns it. If not, ftrace_regs is the same as > pt_regs and ftrace_partial_regs() will return ftrace_regs::regs. > > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> > --- > arch/arm64/include/asm/ftrace.h | 11 +++++++++++ > include/linux/ftrace.h | 11 +++++++++++ > 2 files changed, 22 insertions(+) > > diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h > index ab158196480c..b108cd6718cf 100644 > --- a/arch/arm64/include/asm/ftrace.h > +++ b/arch/arm64/include/asm/ftrace.h > @@ -137,6 +137,17 @@ ftrace_override_function_with_return(struct ftrace_regs *fregs) > fregs->pc = fregs->lr; > } > > +static __always_inline struct pt_regs * > +ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs) > +{ > + memcpy(regs->regs, fregs->regs, sizeof(u64) * 10); Are you intentionally copying that tenth value (fregs.direct_tramp) into pt_regs.regs[9] ? This seems wrong and it looks like it will bite us back one day. Isn't it one of these cases where we can simply use sizeof(fregs->regs) ? > + regs->sp = fregs->sp; > + regs->pc = fregs->pc; > + regs->x[29] = fregs->fp; > + regs->x[30] = fregs->lr; > + return regs; > +} > + > int ftrace_regs_query_register_offset(const char *name); > > int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec); > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h > index 3fb94a1a2461..7f45654441b7 100644 > --- a/include/linux/ftrace.h > +++ b/include/linux/ftrace.h > @@ -155,6 +155,17 @@ static __always_inline struct pt_regs *ftrace_get_regs(struct ftrace_regs *fregs > return arch_ftrace_get_regs(fregs); > } > > +#if !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS) || \ > + defined(CONFIG_HAVE_PT_REGS_COMPAT_FTRACE_REGS) > + > +static __always_inline struct pt_regs * > +ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs) > +{ > + return arch_ftrace_get_regs((struct ftrace_regs *)fregs); > +} I don't think this works. Suppose you are on x86, WITH_ARGS, and with HAVE_PT_REGS_COMPAT_FTRACE_REGS. If you register to ftrace without FTRACE_OPS_FL_SAVE_REGS you will receive a ftrace_regs from the light ftrace pre-trampoline that has a CS register equal to 0 and arch_ftrace_get_regs will return NULL here, which should never happen. Have you tested your series without registering as FTRACE_OPS_FL_SAVE_REGS ?
On Wed, 9 Aug 2023 12:31:27 +0200 Florent Revest <revest@chromium.org> wrote: > On Mon, Aug 7, 2023 at 8:49 AM Masami Hiramatsu (Google) > <mhiramat@kernel.org> wrote: > > > > From: Masami Hiramatsu (Google) <mhiramat@kernel.org> > > > > Add ftrace_partial_regs() which converts the ftrace_regas to pt_regs. > > ftrace_regs* Oops, thanks. > > > If the architecture defines its own ftrace_regs, this copies partial > > registers to pt_regs and returns it. If not, ftrace_regs is the same as > > pt_regs and ftrace_partial_regs() will return ftrace_regs::regs. > > > > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> > > --- > > arch/arm64/include/asm/ftrace.h | 11 +++++++++++ > > include/linux/ftrace.h | 11 +++++++++++ > > 2 files changed, 22 insertions(+) > > > > diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h > > index ab158196480c..b108cd6718cf 100644 > > --- a/arch/arm64/include/asm/ftrace.h > > +++ b/arch/arm64/include/asm/ftrace.h > > @@ -137,6 +137,17 @@ ftrace_override_function_with_return(struct ftrace_regs *fregs) > > fregs->pc = fregs->lr; > > } > > > > +static __always_inline struct pt_regs * > > +ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs) > > +{ > > + memcpy(regs->regs, fregs->regs, sizeof(u64) * 10); > > Are you intentionally copying that tenth value (fregs.direct_tramp) > into pt_regs.regs[9] ? This seems wrong and it looks like it will bite > us back one day. Isn't it one of these cases where we can simply use > sizeof(fregs->regs) ? Ah, sorry, it was my mistake. It should be "sizeof(u64) * 9". I would like to know how can I handle the 'direct_tramp' thing? Can I just ignore it? > > > + regs->sp = fregs->sp; > > + regs->pc = fregs->pc; > > + regs->x[29] = fregs->fp; > > + regs->x[30] = fregs->lr; > > + return regs; > > +} > > + > > int ftrace_regs_query_register_offset(const char *name); > > > > int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec); > > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h > > index 3fb94a1a2461..7f45654441b7 100644 > > --- a/include/linux/ftrace.h > > +++ b/include/linux/ftrace.h > > @@ -155,6 +155,17 @@ static __always_inline struct pt_regs *ftrace_get_regs(struct ftrace_regs *fregs > > return arch_ftrace_get_regs(fregs); > > } > > > > +#if !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS) || \ > > + defined(CONFIG_HAVE_PT_REGS_COMPAT_FTRACE_REGS) > > + > > +static __always_inline struct pt_regs * > > +ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs) > > +{ > > + return arch_ftrace_get_regs((struct ftrace_regs *)fregs); > > +} > > I don't think this works. Suppose you are on x86, WITH_ARGS, and with > HAVE_PT_REGS_COMPAT_FTRACE_REGS. If you register to ftrace without > FTRACE_OPS_FL_SAVE_REGS you will receive a ftrace_regs from the light > ftrace pre-trampoline that has a CS register equal to 0 and > arch_ftrace_get_regs will return NULL here, which should never happen. Yes, Jiri also pointed it. So I simply made it (also remove 'const' from fregs) return &fregs->regs; Thank you, > > Have you tested your series without registering as FTRACE_OPS_FL_SAVE_REGS ?
diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h index ab158196480c..b108cd6718cf 100644 --- a/arch/arm64/include/asm/ftrace.h +++ b/arch/arm64/include/asm/ftrace.h @@ -137,6 +137,17 @@ ftrace_override_function_with_return(struct ftrace_regs *fregs) fregs->pc = fregs->lr; } +static __always_inline struct pt_regs * +ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs) +{ + memcpy(regs->regs, fregs->regs, sizeof(u64) * 10); + regs->sp = fregs->sp; + regs->pc = fregs->pc; + regs->x[29] = fregs->fp; + regs->x[30] = fregs->lr; + return regs; +} + int ftrace_regs_query_register_offset(const char *name); int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec); diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 3fb94a1a2461..7f45654441b7 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -155,6 +155,17 @@ static __always_inline struct pt_regs *ftrace_get_regs(struct ftrace_regs *fregs return arch_ftrace_get_regs(fregs); } +#if !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS) || \ + defined(CONFIG_HAVE_PT_REGS_COMPAT_FTRACE_REGS) + +static __always_inline struct pt_regs * +ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs) +{ + return arch_ftrace_get_regs((struct ftrace_regs *)fregs); +} + +#endif /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS || CONFIG_HAVE_PT_REGS_COMPAT_FTRACE_REGS */ + /* * When true, the ftrace_regs_{get,set}_*() functions may be used on fregs. * Note: this can be true even when ftrace_get_regs() cannot provide a pt_regs.