diff options
| author | Steven J. Magnani <steve@digidescorp.com> | 2010-04-02 13:29:39 -0500 |
|---|---|---|
| committer | Michal Simek <monstr@monstr.eu> | 2010-04-07 07:27:25 +0200 |
| commit | d2bf98e6fc2612cbd2fc40f75a1e2c5d60262331 (patch) | |
| tree | 7a69042d5f841ee7f66f0d6661df09c9fdfbe402 /arch/microblaze | |
| parent | 0fdf86754f70e813845af4abaa805165ce57a0bb (diff) | |
| download | lwn-d2bf98e6fc2612cbd2fc40f75a1e2c5d60262331.tar.gz lwn-d2bf98e6fc2612cbd2fc40f75a1e2c5d60262331.zip | |
microblaze: Fix ftrace_update_ftrace_func panic
The Microblaze dynamic ftrace code assumes a call ordering that is not met
in all scenarios. Specifically, executing a command similar to:
echo 105 > /sys/kernel/debug/tracing/set_ftrace_pid
before any other tracing-related commands results in a kernel panic:
BUG: failure at arch/microblaze/kernel/ftrace.c:198/ftrace_update_ftrace_func()!
Recoding ftrace_update_ftrace_func() to use &ftrace_caller directly eliminates
the need to capture its address elsewhere (and thus rely on a particular call
sequence).
Signed-off-by: Steven J. Magnani <steve@digidescorp.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>
Diffstat (limited to 'arch/microblaze')
| -rw-r--r-- | arch/microblaze/kernel/ftrace.c | 12 |
1 files changed, 3 insertions, 9 deletions
diff --git a/arch/microblaze/kernel/ftrace.c b/arch/microblaze/kernel/ftrace.c index 388b31ca65a1..515feb404555 100644 --- a/arch/microblaze/kernel/ftrace.c +++ b/arch/microblaze/kernel/ftrace.c @@ -151,13 +151,10 @@ int ftrace_make_nop(struct module *mod, return ret; } -static int ret_addr; /* initialized as 0 by default */ - /* I believe that first is called ftrace_make_nop before this function */ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) { int ret; - ret_addr = addr; /* saving where the barrier jump is */ pr_debug("%s: addr:0x%x, rec->ip: 0x%x, imm:0x%x\n", __func__, (unsigned int)addr, (unsigned int)rec->ip, imm); ret = ftrace_modify_code(rec->ip, imm); @@ -194,12 +191,9 @@ int ftrace_update_ftrace_func(ftrace_func_t func) ret = ftrace_modify_code(ip, upper); ret += ftrace_modify_code(ip + 4, lower); - /* We just need to remove the rtsd r15, 8 by NOP */ - BUG_ON(!ret_addr); - if (ret_addr) - ret += ftrace_modify_code(ret_addr, MICROBLAZE_NOP); - else - ret = 1; /* fault */ + /* We just need to replace the rtsd r15, 8 with NOP */ + ret += ftrace_modify_code((unsigned long)&ftrace_caller, + MICROBLAZE_NOP); /* All changes are done - lets do caches consistent */ flush_icache(); |