Messages in this thread | | | Date | Tue, 30 Jul 2019 11:47:46 +0100 | From | Russell King - ARM Linux admin <> | Subject | Re: [RFC PATCH] ARM: zynq: Use memcpy_toio instead of memcpy on smp bring-up |
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On Tue, Jul 30, 2019 at 12:43:26AM -0400, Luis Araneda wrote: > This fixes a kernel panic (read overflow) on memcpy when > FORTIFY_SOURCE is enabled. > > The computed size of memcpy args are: > - p_size (dst): 4294967295 = (size_t) -1 > - q_size (src): 1 > - size (len): 8 > > Additionally, the memory is marked as __iomem, so one of > the memcpy_* functions should be used for read/write > > Signed-off-by: Luis Araneda <luaraneda@gmail.com> > --- > > For anyone trying to reproduce / debug this, it panics > before the console has any output. > I used JTAG to find the panic, but I had to comment-out > the call to "zynq_slcr_cpu_stop" as it stops the JTAG > interface and the connection is dropped, at least with OpenOCD. > > I run-tested this on a Digilent Zybo Z7 board > --- > arch/arm/mach-zynq/platsmp.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm/mach-zynq/platsmp.c b/arch/arm/mach-zynq/platsmp.c > index a7cfe07156f4..407abade7336 100644 > --- a/arch/arm/mach-zynq/platsmp.c > +++ b/arch/arm/mach-zynq/platsmp.c > @@ -57,7 +57,7 @@ int zynq_cpun_start(u32 address, int cpu) > * 0x4: Jump by mov instruction > * 0x8: Jumping address > */ > - memcpy((__force void *)zero, &zynq_secondary_trampoline, > + memcpy_toio(zero, &zynq_secondary_trampoline, > trampoline_size); > writel(address, zero + trampoline_size);
I'm not convinced that this is correct. It looks like zynq_secondary_trampoline could be either ARM or Thumb code - there is no .arm directive before it. If it's ARM code, then this is fine. If Thumb code, then zynq_secondary_trampoline will be offset by one, and we will miss copying the first byte of code.
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