linux-kernel - [PATCH 5.7 349/376] RISC-V: Dont mark init section as non-executable

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Date:   Fri, 19 Jun 2020 16:34:27 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Anup Patel <anup.patel@....com>,
        Zong Li <zong.li@...ive.com>,
        Atish Patra <atish.patra@....com>,
        Palmer Dabbelt <palmerdabbelt@...gle.com>
Subject: [PATCH 5.7 349/376] RISC-V: Dont mark init section as non-executable

From: Anup Patel <anup.patel@....com>

commit 4e0f9e3a6104261f25b16fcab02fc96f5666ba11 upstream.

The head text section (i.e. _start, secondary_start_sbi, etc) and the
init section fall under same page table level-1 mapping.

Currently, the runtime CPU hotplug is broken because we are marking
init section as non-executable which in-turn marks head text section
as non-executable.

Further investigating other architectures, it seems marking the init
section as non-executable is redundant because the init section pages
are anyway poisoned and freed.

To fix broken runtime CPU hotplug, we simply remove the code marking
the init section as non-executable.

Fixes: d27c3c90817e ("riscv: add STRICT_KERNEL_RWX support")
Cc: stable@...r.kernel.org
Signed-off-by: Anup Patel <anup.patel@....com>
Reviewed-by: Zong Li <zong.li@...ive.com>
Reviewed-by: Atish Patra <atish.patra@....com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@...gle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/riscv/mm/init.c |   11 -----------
 1 file changed, 11 deletions(-)

--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -479,17 +479,6 @@ static void __init setup_vm_final(void)
 	csr_write(CSR_SATP, PFN_DOWN(__pa_symbol(swapper_pg_dir)) | SATP_MODE);
 	local_flush_tlb_all();
 }
-
-void free_initmem(void)
-{
-	unsigned long init_begin = (unsigned long)__init_begin;
-	unsigned long init_end = (unsigned long)__init_end;
-
-	/* Make the region as non-execuatble. */
-	set_memory_nx(init_begin, (init_end - init_begin) >> PAGE_SHIFT);
-	free_initmem_default(POISON_FREE_INITMEM);
-}
-
 #else
 asmlinkage void __init setup_vm(uintptr_t dtb_pa)
 {