Messages in this thread | | | Date | Mon, 05 Apr 2010 16:26:17 +0200 | From | Michal Simek <> | Subject | Re: [PATCH] microblaze: Fix ftrace_update_ftrace_func panic |
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Steven J. Magnani wrote: > 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).
I would like to replicate this problem to see that there is. I am not able to reach this fault Please copy & paste log with your commands.
Thanks, Michal
> > Signed-off-by: Steven J. Magnani <steve@digidescorp.com> > --- > diff -uprN a/arch/microblaze/kernel/ftrace.c b/arch/microblaze/kernel/ftrace.c > --- a/arch/microblaze/kernel/ftrace.c 2010-04-02 13:10:54.000000000 -0500 > +++ b/arch/microblaze/kernel/ftrace.c 2010-04-02 13:13:29.000000000 -0500 > @@ -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_fun > 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(); >
-- Michal Simek, Ing. (M.Eng) w: www.monstr.eu p: +42-0-721842854 Maintainer of Linux kernel 2.6 Microblaze Linux - http://www.monstr.eu/fdt/ Microblaze U-BOOT custodian
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