Unverified Commit 420370f3 authored by Alexandre Ghiti's avatar Alexandre Ghiti Committed by Palmer Dabbelt
Browse files

riscv: Check if the code to patch lies in the exit section 



Otherwise we fall through to vmalloc_to_page() which panics since the
address does not lie in the vmalloc region.

Fixes: 043cb41a ("riscv: introduce interfaces to patch kernel code")
Signed-off-by: default avatarAlexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: default avatarCharlie Jenkins <charlie@rivosinc.com>
Link: https://lore.kernel.org/r/20231214091926.203439-1-alexghiti@rivosinc.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent ed5b7cfd

arch/riscv/include/asm/sections.h

+1 −0
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ extern char _start_kernel[]; 
extern char __init_data_begin[], __init_data_end[];

extern char __init_text_begin[], __init_text_end[];

extern char __alt_start[], __alt_end[];

extern char __exittext_begin[], __exittext_end[];



static inline bool is_va_kernel_text(uintptr_t va)

{

arch/riscv/kernel/patch.c

+10 −1
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <asm/fixmap.h>

#include <asm/ftrace.h>

#include <asm/patch.h>

#include <asm/sections.h>



struct patch_insn {

	void *addr;
@@ -25,6 +26,14 @@ struct patch_insn { 
int riscv_patch_in_stop_machine = false;



#ifdef CONFIG_MMU



static inline bool is_kernel_exittext(uintptr_t addr)

{

	return system_state < SYSTEM_RUNNING &&

		addr >= (uintptr_t)__exittext_begin &&

		addr < (uintptr_t)__exittext_end;

}



/*

 * The fix_to_virt(, idx) needs a const value (not a dynamic variable of

 * reg-a0) or BUILD_BUG_ON failed with "idx >= __end_of_fixed_addresses".
@@ -35,7 +44,7 @@ static __always_inline void *patch_map(void *addr, const unsigned int fixmap) 
	uintptr_t uintaddr = (uintptr_t) addr;

	struct page *page;



	if (core_kernel_text(uintaddr))

	if (core_kernel_text(uintaddr) || is_kernel_exittext(uintaddr))

		page = phys_to_page(__pa_symbol(addr));

	else if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX))

		page = vmalloc_to_page(addr);

arch/riscv/kernel/vmlinux-xip.lds.S

+2 −0
Original line number Diff line number Diff line
@@ -29,10 +29,12 @@ SECTIONS 
	HEAD_TEXT_SECTION

	INIT_TEXT_SECTION(PAGE_SIZE)

	/* we have to discard exit text and such at runtime, not link time */

	__exittext_begin = .;

	.exit.text :

	{

		EXIT_TEXT

	}

	__exittext_end = .;



	.text : {

		_text = .;

arch/riscv/kernel/vmlinux.lds.S

+2 −0
Original line number Diff line number Diff line
@@ -69,10 +69,12 @@ SECTIONS 
		__soc_builtin_dtb_table_end = .;

	}

	/* we have to discard exit text and such at runtime, not link time */

	__exittext_begin = .;

	.exit.text :

	{

		EXIT_TEXT

	}

	__exittext_end = .;



	__init_text_end = .;

	. = ALIGN(SECTION_ALIGN);