RISC-V: take text_mutex during alternative patching
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>
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>
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