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

[ Upstream commit 420370f3ae3d3b883813fd3051a38805160b2b9f ]

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

Fixes: 043cb41a85 ("riscv: introduce interfaces to patch kernel code")
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Link: https://lore.kernel.org/r/20231214091926.203439-1-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Alexandre Ghiti 2023-12-14 10:19:26 +01:00 committed by Greg Kroah-Hartman
parent 9ad0ab0bbc
commit 890cfe5337
4 changed files with 15 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/riscv/include/asm/sections.h
View File

@ -13,6 +13,7 @@ extern char _start_kernel[];
extern char __init_data_begin[], __init_data_end[]; extern char __init_data_begin[], __init_data_end[];
extern char __init_text_begin[], __init_text_end[]; extern char __init_text_begin[], __init_text_end[];
extern char __alt_start[], __alt_end[]; extern char __alt_start[], __alt_end[];
extern char __exittext_begin[], __exittext_end[];
static inline bool is_va_kernel_text(uintptr_t va) static inline bool is_va_kernel_text(uintptr_t va)
{ {

11
arch/riscv/kernel/patch.c
View File

@ -13,6 +13,7 @@
#include <asm/fixmap.h> #include <asm/fixmap.h>
#include <asm/ftrace.h> #include <asm/ftrace.h>
#include <asm/patch.h> #include <asm/patch.h>
#include <asm/sections.h>
struct patch_insn { struct patch_insn {
void *addr; void *addr;
@ -23,6 +24,14 @@ struct patch_insn {
int riscv_patch_in_stop_machine = false; int riscv_patch_in_stop_machine = false;
#ifdef CONFIG_MMU #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 * 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". * reg-a0) or BUILD_BUG_ON failed with "idx >= __end_of_fixed_addresses".
@ -33,7 +42,7 @@ static __always_inline void *patch_map(void *addr, const unsigned int fixmap)
uintptr_t uintaddr = (uintptr_t) addr; uintptr_t uintaddr = (uintptr_t) addr;
struct page *page; struct page *page;
if (core_kernel_text(uintaddr)) if (core_kernel_text(uintaddr) || is_kernel_exittext(uintaddr))
page = phys_to_page(__pa_symbol(addr)); page = phys_to_page(__pa_symbol(addr));
else if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) else if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
page = vmalloc_to_page(addr); page = vmalloc_to_page(addr);

2
arch/riscv/kernel/vmlinux-xip.lds.S
View File

@ -29,10 +29,12 @@ SECTIONS
HEAD_TEXT_SECTION HEAD_TEXT_SECTION
INIT_TEXT_SECTION(PAGE_SIZE) INIT_TEXT_SECTION(PAGE_SIZE)
/* we have to discard exit text and such at runtime, not link time */ /* we have to discard exit text and such at runtime, not link time */
__exittext_begin = .;
.exit.text : .exit.text :
{ {
EXIT_TEXT EXIT_TEXT
} }
__exittext_end = .;
.text : { .text : {
_text = .; _text = .;

2
arch/riscv/kernel/vmlinux.lds.S
View File

@ -72,10 +72,12 @@ SECTIONS
__soc_builtin_dtb_table_end = .; __soc_builtin_dtb_table_end = .;
} }
/* we have to discard exit text and such at runtime, not link time */ /* we have to discard exit text and such at runtime, not link time */
__exittext_begin = .;
.exit.text : .exit.text :
{ {
EXIT_TEXT EXIT_TEXT
} }
__exittext_end = .;
__init_text_end = .; __init_text_end = .;
. = ALIGN(SECTION_ALIGN); . = ALIGN(SECTION_ALIGN);