Re: [PATCH 6.2 113/141] RISC-V: take text_mutex during alternative patching

[Conor Dooley <conor.dooley@microchip.com>]

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On Thu, Mar 16, 2023 at 08:26:55AM +0100, Greg Kroah-Hartman wrote:
> On Wed, Mar 15, 2023 at 01:10:04PM +0000, Conor Dooley wrote:
> > Hey Greg,
> > 
> > Looks like the authorship for this commit has been lost as part of
> > backporting.
> > 
> > On Wed, Mar 15, 2023 at 01:13:36PM +0100, Greg Kroah-Hartman wrote:
> > > [ Upstream commit 9493e6f3ce02f44c21aa19f3cbf3b9aa05479d06 ]
> > > 
> > > Guenter reported a splat during boot, that Samuel pointed out was the
> > > lockdep assertion failing in patch_insn_write():
> > > 
> > > WARNING: CPU: 0 PID: 0 at arch/riscv/kernel/patch.c:63 patch_insn_write+0x222/0x2f6
> > > epc : patch_insn_write+0x222/0x2f6
> > >  ra : patch_insn_write+0x21e/0x2f6
> > > epc : ffffffff800068c6 ra : ffffffff800068c2 sp : ffffffff81803df0
> > >  gp : ffffffff81a1ab78 tp : ffffffff81814f80 t0 : ffffffffffffe000
> > >  t1 : 0000000000000001 t2 : 4c45203a76637369 s0 : ffffffff81803e40
> > >  s1 : 0000000000000004 a0 : 0000000000000000 a1 : ffffffffffffffff
> > >  a2 : 0000000000000004 a3 : 0000000000000000 a4 : 0000000000000001
> > >  a5 : 0000000000000000 a6 : 0000000000000000 a7 : 0000000052464e43
> > >  s2 : ffffffff80b4889c s3 : 000000000000082c s4 : ffffffff80b48828
> > >  s5 : 0000000000000828 s6 : ffffffff8131a0a0 s7 : 0000000000000fff
> > >  s8 : 0000000008000200 s9 : ffffffff8131a520 s10: 0000000000000018
> > >  s11: 000000000000000b t3 : 0000000000000001 t4 : 000000000000000d
> > >  t5 : ffffffffd8180000 t6 : ffffffff81803bc8
> > > status: 0000000200000100 badaddr: 0000000000000000 cause: 0000000000000003
> > > [<ffffffff800068c6>] patch_insn_write+0x222/0x2f6
> > > [<ffffffff80006a36>] patch_text_nosync+0xc/0x2a
> > > [<ffffffff80003b86>] riscv_cpufeature_patch_func+0x52/0x98
> > > [<ffffffff80003348>] _apply_alternatives+0x46/0x86
> > > [<ffffffff80c02d36>] apply_boot_alternatives+0x3c/0xfa
> > > [<ffffffff80c03ad8>] setup_arch+0x584/0x5b8
> > > [<ffffffff80c0075a>] start_kernel+0xa2/0x8f8
> > > 
> > > This issue was exposed by 702e64550b12 ("riscv: fpu: switch has_fpu() to
> > > riscv_has_extension_likely()"), as it is the patching in has_fpu() that
> > > triggers the splats in Guenter's report.
> > > 
> > > Take the text_mutex before doing any code patching to satisfy lockdep.
> > > 
> > > Fixes: ff689fd21cb1 ("riscv: add RISC-V Svpbmt extension support")
> > > Fixes: a35707c3d850 ("riscv: add memory-type errata for T-Head")
> > > Fixes: 1a0e5dbd3723 ("riscv: sifive: Add SiFive alternative ports")
> > > Reported-by: Guenter Roeck <linux@roeck-us.net>
> > > Link: https://lore.kernel.org/all/20230212154333.GA3760469@roeck-us.net/
> > > Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
> > 
> > The original author on the submitted patch matched this signoff here,
> > not sure what went wrong along the way.
> 
> I do not understand, sorry, the signed off by area of this commit in the
> queue seems to match up with what is in Linus's tree with the exception
> that Sasha:
> 
> > > Reviewed-by: Samuel Holland <samuel@sholland.org>
> > > Tested-by: Guenter Roeck <linux@roeck-us.net>
> > > Link: https://lore.kernel.org/r/20230212194735.491785-1-conor@kernel.org
> > > Cc: stable@vger.kernel.org
> > > Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
> > > Signed-off-by: Sasha Levin <sashal@kernel.org>
> 
> Added himself to the end of it.
> 
> What exactly is not correct here?

The author of the patch is not the same as Linus' tree, which,
admittedly, is hard to tell from a patch email. In Linus' tree, the
author is me, but it's been attributed to Sasha somewhere along the way.

Perhaps this is something normal for stable stuff, I usually don't go
digging around in the stable-rc tree, but I wanted to make sure that
this stuff was backported correctly.
The cover-letter for this patch also shows the incorrect author for this
patch, but I am only noticing that now.

Cheers,
Conor.

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