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riscv: patch: Flush the icache right after patching to avoid illegal insns

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We cannot delay the icache flush after patching some functions as we may
have patched a function that will get called before the icache flush.

The only way to completely avoid such scenario is by flushing the icache
as soon as we patch a function. This will probably be costly as we don't
batch the icache maintenance anymore.

Fixes: 6ca445d8af ("riscv: Fix early ftrace nop patching")
Reported-by: Conor Dooley <conor.dooley@microchip.com>
Closes: https://lore.kernel.org/linux-riscv/20240613-lubricant-breath-061192a9489a@wendy/
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Andy Chiu <andy.chiu@sifive.com>
Link: https://lore.kernel.org/r/20240624082141.153871-1-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Alexandre Ghiti 2024-06-24 10:21:41 +02:00 committed by Palmer Dabbelt
parent 04a2aef59c
commit edf2d546bf
No known key found for this signature in database
GPG key ID: 2E1319F35FBB1889
2 changed files with 20 additions and 13 deletions
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7
arch/riscv/kernel/ftrace.c
View file

@ -120,9 +120,6 @@ int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
out = ftrace_make_nop(mod, rec, MCOUNT_ADDR);
mutex_unlock(&text_mutex);
if (!mod)
local_flush_icache_range(rec->ip, rec->ip + MCOUNT_INSN_SIZE);
return out;
}
@ -156,9 +153,9 @@ static int __ftrace_modify_code(void *data)
} else {
while (atomic_read(&param->cpu_count) <= num_online_cpus())
cpu_relax();
}
local_flush_icache_all();
local_flush_icache_all();
}
return 0;
}

26
arch/riscv/kernel/patch.c
View file

@ -89,6 +89,14 @@ static int __patch_insn_set(void *addr, u8 c, size_t len)
memset(waddr, c, len);
/*
* We could have just patched a function that is about to be
* called so make sure we don't execute partially patched
* instructions by flushing the icache as soon as possible.
*/
local_flush_icache_range((unsigned long)waddr,
(unsigned long)waddr + len);
patch_unmap(FIX_TEXT_POKE0);
if (across_pages)
@ -135,6 +143,14 @@ static int __patch_insn_write(void *addr, const void *insn, size_t len)
ret = copy_to_kernel_nofault(waddr, insn, len);
/*
* We could have just patched a function that is about to be
* called so make sure we don't execute partially patched
* instructions by flushing the icache as soon as possible.
*/
local_flush_icache_range((unsigned long)waddr,
(unsigned long)waddr + len);
patch_unmap(FIX_TEXT_POKE0);
if (across_pages)
@ -189,9 +205,6 @@ int patch_text_set_nosync(void *addr, u8 c, size_t len)
ret = patch_insn_set(tp, c, len);
if (!ret)
flush_icache_range((uintptr_t)tp, (uintptr_t)tp + len);
return ret;
}
NOKPROBE_SYMBOL(patch_text_set_nosync);
@ -224,9 +237,6 @@ int patch_text_nosync(void *addr, const void *insns, size_t len)
ret = patch_insn_write(tp, insns, len);
if (!ret)
flush_icache_range((uintptr_t) tp, (uintptr_t) tp + len);
return ret;
}
NOKPROBE_SYMBOL(patch_text_nosync);
@ -253,9 +263,9 @@ static int patch_text_cb(void *data)
} else {
while (atomic_read(&patch->cpu_count) <= num_online_cpus())
cpu_relax();
}
local_flush_icache_all();
local_flush_icache_all();
}
return ret;
}