From mboxrd@z Thu Jan 1 00:00:00 1970 From: compudj@krystal.dyndns.org (Mathieu Desnoyers) Date: Mon, 19 Sep 2011 10:57:19 -0400 Subject: [ltt-dev] [PATCH V1] ARM: Set bit 0 for thumb mode in kallsyms_lookup_name returned address In-Reply-To: <1316422804-32562-1-git-send-email-avik.sil@linaro.org> References: <1316422804-32562-1-git-send-email-avik.sil@linaro.org> Message-ID: * Avik Sil (avik.sil at linaro.org) wrote: > This patch fixes the undefined instruction oops due to execution > of thumb-2 code in ARM mode. The zero bit in the symbol address > returned by kallsyms_lookup_name is not set, leading to switching > to ARM mode that generates oops while executing thumb-2 code. For > detailed discussion, see [1]. > [1] http://lists.casi.polymtl.ca/pipermail/ltt-dev/2011-September/005176.html > > v1: > - include wrapper function kallsyms_lookup_funcptr as suggested > by Dave Martin > > Signed-off-by: Avik Sil Merged, thanks! Mathieu > --- > lttng-context-prio.c | 3 ++- > wrapper/ftrace.h | 5 +++-- > wrapper/kallsyms.h | 28 ++++++++++++++++++++++++++++ > wrapper/splice.c | 3 ++- > wrapper/vmalloc.h | 3 ++- > 5 files changed, 37 insertions(+), 5 deletions(-) > create mode 100644 wrapper/kallsyms.h > > diff --git a/lttng-context-prio.c b/lttng-context-prio.c > index ad1c42f..1ee3a54 100644 > --- a/lttng-context-prio.c > +++ b/lttng-context-prio.c > @@ -13,6 +13,7 @@ > #include "ltt-events.h" > #include "wrapper/ringbuffer/frontend_types.h" > #include "wrapper/vmalloc.h" > +#include "wrapper/kallsyms.h" > #include "ltt-tracer.h" > > static > @@ -20,7 +21,7 @@ int (*wrapper_task_prio_sym)(struct task_struct *t); > > int wrapper_task_prio_init(void) > { > - wrapper_task_prio_sym = (void *) kallsyms_lookup_name("task_prio"); > + wrapper_task_prio_sym = (void *) kallsyms_lookup_funcptr("task_prio"); > if (!wrapper_task_prio_sym) { > printk(KERN_WARNING "LTTng: task_prio symbol lookup failed.\n"); > return -EINVAL; > diff --git a/wrapper/ftrace.h b/wrapper/ftrace.h > index 9c18cc5..ace33c5 100644 > --- a/wrapper/ftrace.h > +++ b/wrapper/ftrace.h > @@ -16,6 +16,7 @@ > #ifdef CONFIG_KALLSYMS > > #include > +#include "kallsyms.h" > > static inline > int wrapper_register_ftrace_function_probe(char *glob, > @@ -24,7 +25,7 @@ int wrapper_register_ftrace_function_probe(char *glob, > int (*register_ftrace_function_probe_sym)(char *glob, > struct ftrace_probe_ops *ops, void *data); > > - register_ftrace_function_probe_sym = (void *) kallsyms_lookup_name("register_ftrace_function_probe"); > + register_ftrace_function_probe_sym = (void *) kallsyms_lookup_funcptr("register_ftrace_function_probe"); > if (register_ftrace_function_probe_sym) { > return register_ftrace_function_probe_sym(glob, ops, data); > } else { > @@ -40,7 +41,7 @@ void wrapper_unregister_ftrace_function_probe(char *glob, > void (*unregister_ftrace_function_probe_sym)(char *glob, > struct ftrace_probe_ops *ops, void *data); > > - unregister_ftrace_function_probe_sym = (void *) kallsyms_lookup_name("unregister_ftrace_function_probe"); > + unregister_ftrace_function_probe_sym = (void *) kallsyms_lookup_funcptr("unregister_ftrace_function_probe"); > if (unregister_ftrace_function_probe_sym) { > unregister_ftrace_function_probe_sym(glob, ops, data); > } else { > diff --git a/wrapper/kallsyms.h b/wrapper/kallsyms.h > new file mode 100644 > index 0000000..bb45f38 > --- /dev/null > +++ b/wrapper/kallsyms.h > @@ -0,0 +1,28 @@ > +#ifndef _LTT_WRAPPER_KALLSYMS_H > +#define _LTT_WRAPPER_KALLSYMS_H > + > +/* > + * Copyright (C) 2011 Avik Sil (avik.sil at linaro.org) > + * > + * wrapper around kallsyms_lookup_name. Implements arch-dependent code for > + * arches where the address of the start of the function body is different > + * from the pointer which can be used to call the function, e.g. ARM THUMB2. > + * > + * Dual LGPL v2.1/GPL v2 license. > + */ > + > +static inline > +unsigned long kallsyms_lookup_funcptr(const char *name) > +{ > + unsigned long addr; > + > + addr = kallsyms_lookup_name(name); > +#ifdef CONFIG_ARM > +#ifdef CONFIG_THUMB2_KERNEL > + if (addr) > + addr |= 1; /* set bit 0 in address for thumb mode */ > +#endif > +#endif > + return addr; > +} > +#endif /* _LTT_WRAPPER_KALLSYMS_H */ > diff --git a/wrapper/splice.c b/wrapper/splice.c > index edc499c..ba224ee 100644 > --- a/wrapper/splice.c > +++ b/wrapper/splice.c > @@ -13,6 +13,7 @@ > #include > #include > #include > +#include "kallsyms.h" > > static > ssize_t (*splice_to_pipe_sym)(struct pipe_inode_info *pipe, > @@ -22,7 +23,7 @@ ssize_t wrapper_splice_to_pipe(struct pipe_inode_info *pipe, > struct splice_pipe_desc *spd) > { > if (!splice_to_pipe_sym) > - splice_to_pipe_sym = (void *) kallsyms_lookup_name("splice_to_pipe"); > + splice_to_pipe_sym = (void *) kallsyms_lookup_funcptr("splice_to_pipe"); > if (splice_to_pipe_sym) { > return splice_to_pipe_sym(pipe, spd); > } else { > diff --git a/wrapper/vmalloc.h b/wrapper/vmalloc.h > index 7d87855..765f2ad 100644 > --- a/wrapper/vmalloc.h > +++ b/wrapper/vmalloc.h > @@ -14,13 +14,14 @@ > #ifdef CONFIG_KALLSYMS > > #include > +#include "kallsyms.h" > > static inline > void wrapper_vmalloc_sync_all(void) > { > void (*vmalloc_sync_all_sym)(void); > > - vmalloc_sync_all_sym = (void *) kallsyms_lookup_name("vmalloc_sync_all"); > + vmalloc_sync_all_sym = (void *) kallsyms_lookup_funcptr("vmalloc_sync_all"); > if (vmalloc_sync_all_sym) { > vmalloc_sync_all_sym(); > } else { > -- > 1.7.0.4 > > > _______________________________________________ > ltt-dev mailing list > ltt-dev at lists.casi.polymtl.ca > http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev > -- Mathieu Desnoyers Operating System Efficiency R&D Consultant EfficiOS Inc. http://www.efficios.com