From 9493e6f3ce02f44c21aa19f3cbf3b9aa05479d06 Mon Sep 17 00:00:00 2001 From: Conor Dooley Date: Sun, 12 Feb 2023 19:47:36 +0000 Subject: 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 [] patch_insn_write+0x222/0x2f6 [] patch_text_nosync+0xc/0x2a [] riscv_cpufeature_patch_func+0x52/0x98 [] _apply_alternatives+0x46/0x86 [] apply_boot_alternatives+0x3c/0xfa [] setup_arch+0x584/0x5b8 [] 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 Link: https://lore.kernel.org/all/20230212154333.GA3760469@roeck-us.net/ Signed-off-by: Conor Dooley Reviewed-by: Samuel Holland Tested-by: Guenter Roeck Link: https://lore.kernel.org/r/20230212194735.491785-1-conor@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt --- arch/riscv/errata/sifive/errata.c | 3 +++ arch/riscv/errata/thead/errata.c | 8 ++++++-- arch/riscv/kernel/cpufeature.c | 4 ++++ 3 files changed, 13 insertions(+), 2 deletions(-) diff --git a/arch/riscv/errata/sifive/errata.c b/arch/riscv/errata/sifive/errata.c index ef9a4eec0dba..da55cb247e89 100644 --- a/arch/riscv/errata/sifive/errata.c +++ b/arch/riscv/errata/sifive/errata.c @@ -4,6 +4,7 @@ */ #include +#include #include #include #include @@ -107,8 +108,10 @@ void __init_or_module sifive_errata_patch_func(struct alt_entry *begin, tmp = (1U << alt->errata_id); if (cpu_req_errata & tmp) { + mutex_lock(&text_mutex); patch_text_nosync(ALT_OLD_PTR(alt), ALT_ALT_PTR(alt), alt->alt_len); + mutex_lock(&text_mutex); cpu_apply_errata |= tmp; } } diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c index 1dd90a5f86f0..3b96a06d3c54 100644 --- a/arch/riscv/errata/thead/errata.c +++ b/arch/riscv/errata/thead/errata.c @@ -5,6 +5,7 @@ #include #include +#include #include #include #include @@ -101,10 +102,13 @@ void __init_or_module thead_errata_patch_func(struct alt_entry *begin, struct al altptr = ALT_ALT_PTR(alt); /* On vm-alternatives, the mmu isn't running yet */ - if (stage == RISCV_ALTERNATIVES_EARLY_BOOT) + if (stage == RISCV_ALTERNATIVES_EARLY_BOOT) { memcpy(oldptr, altptr, alt->alt_len); - else + } else { + mutex_lock(&text_mutex); patch_text_nosync(oldptr, altptr, alt->alt_len); + mutex_unlock(&text_mutex); + } } } diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c index 21fb567e1b22..59d58ee0f68d 100644 --- a/arch/riscv/kernel/cpufeature.c +++ b/arch/riscv/kernel/cpufeature.c @@ -10,6 +10,7 @@ #include #include #include +#include #include #include #include @@ -292,8 +293,11 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin, oldptr = ALT_OLD_PTR(alt); altptr = ALT_ALT_PTR(alt); + + mutex_lock(&text_mutex); patch_text_nosync(oldptr, altptr, alt->alt_len); riscv_alternative_fix_offsets(oldptr, alt->alt_len, oldptr - altptr); + mutex_unlock(&text_mutex); } } #endif -- cgit v1.2.3-58-ga151