| Message ID | 201401071512.34016.arnd@arndb.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Arnd, On Tue, Jan 7, 2014 at 10:12 PM, Arnd Bergmann <arnd@arndb.de> wrote: > On Monday 28 October 2013, Ming Lei wrote: >> This patch uses CONFIG_PAGE_OFFSET to filter symbols which >> are not in kernel address space because these symbols are >> generally for generating code purpose and can't be run at >> kernel mode, so we needn't keep them in /proc/kallsyms. >> >> For example, on ARM there are some symbols which are >> linked in relocatable code section, then perf can't parse >> symbols any more from /proc/kallsyms, and this patch fixes >> the problem. >> >> Cc: Russell King <linux@arm.linux.org.uk> >> Cc: linux-arm-kernel@lists.infradead.org >> Cc: Michal Marek <mmarek@suse.cz> >> Acked-by: Rusty Russell <rusty@rustcorp.com.au> >> Signed-off-by: Ming Lei <tom.leiming@gmail.com> > > Sorry for the late report, but I seem to have encountered a problem with this > patch, now that it has made it into all stable kernels. > > When linking an ARM nommu kernel, I get the output "No valid symbol." twice, > from scripts/kallsyms. The problem evidently is that PAGE_OFFSET is still > set to 0xC0000000 on ARM NOMMU builds but the kernel is linked to start at > PLAT_PHYS_OFFSET instead, which may be elsehwere. For most platforms, > this is defined in Kconfig these days, so we could get away with > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > index d1e4098..c477a7c 100644 > --- a/arch/arm/Kconfig > +++ b/arch/arm/Kconfig > @@ -1592,6 +1592,7 @@ endchoice > > config PAGE_OFFSET > hex > + default PHYS_OFFSET if !MMU > default 0x40000000 if VMSPLIT_1G > default 0x80000000 if VMSPLIT_2G > default 0xC0000000 > > but there are still a few ARM platforms that define their own PLAT_PHYS_OFFSET > in memory.h, and it wouldn't help on non-ARM systems that might have the same > problem. We had posted two patches to address the problem, see below link: http://lists.scusting.com/index.php?t=msg&goto=1726509&S=Google Thanks,
On Tuesday 07 January 2014 22:33:24 Ming Lei wrote: > On Tue, Jan 7, 2014 at 10:12 PM, Arnd Bergmann <arnd@arndb.de> wrote: > > On Monday 28 October 2013, Ming Lei wrote: > > We had posted two patches to address the problem, see below link: > > http://lists.scusting.com/index.php?t=msg&goto=1726509&S=Google The patch "scripts/link-vmlinux.sh: only filter kernel symbols for arm" has made it in now, which is good for all other architectures, but it makes no difference for nommu-arm, because CONFIG_PAGE_OFFSET is still set. The second patch from Jonathan Austin has not been applied yet, as of today's linux-next, and it's exactly what I suggested. However it won't work on ARM platforms that define their own PLAT_PHYS_OFFSET: ebsa110, ep93xx, exynos, footbridge, integrator, iop13xx, ks8695, omap1, realview, rpc, s5pv210 and sa1100. Fortunately these all have MMUs, so in practice it won't hurt, but it doesn't seem correct. Arnd
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index d1e4098..c477a7c 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -1592,6 +1592,7 @@ endchoice config PAGE_OFFSET hex + default PHYS_OFFSET if !MMU default 0x40000000 if VMSPLIT_1G default 0x80000000 if VMSPLIT_2G default 0xC0000000