From: Qing Zhang <zhangqing@loongson.cn>
To: Andrey Ryabinin <ryabinin.a.a@gmail.com>,
Jonathan Corbet <corbet@lwn.net>,
Huacai Chen <chenhuacai@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Potapenko <glider@google.com>,
Andrey Konovalov <andreyknvl@gmail.com>,
Dmitry Vyukov <dvyukov@google.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
WANG Xuerui <kernel@xen0n.name>,
Jiaxun Yang <jiaxun.yang@flygoat.com>,
kasan-dev@googlegroups.com, linux-doc@vger.kernel.org,
linux-mm@kvack.org, loongarch@lists.linux.dev,
linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: [PATCH v3 3/4] LoongArch: Simplify the processing of jumping new kernel for KASLR
Date: Fri, 12 May 2023 09:57:30 +0800 [thread overview]
Message-ID: <20230512015731.23787-4-zhangqing@loongson.cn> (raw)
In-Reply-To: <20230512015731.23787-1-zhangqing@loongson.cn>
Modified relocate_kernel() doesn't return new kernel's entry point but
the random_offset. In this way we share the start_kernel() processing
with the normal kernel, which avoids calling 'jr a0' directly and allows
some other operations (e.g, kasan_early_init) before start_kernel() when
KASLR (CONFIG_RANDOMIZE_BASE) is turned on.
Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
---
arch/loongarch/include/asm/setup.h | 2 +-
arch/loongarch/kernel/head.S | 11 ++++++-----
arch/loongarch/kernel/relocate.c | 8 ++------
3 files changed, 9 insertions(+), 12 deletions(-)
diff --git a/arch/loongarch/include/asm/setup.h b/arch/loongarch/include/asm/setup.h
index be05c0e706a2..2dca0d1dd90a 100644
--- a/arch/loongarch/include/asm/setup.h
+++ b/arch/loongarch/include/asm/setup.h
@@ -33,7 +33,7 @@ extern long __la_abs_end;
extern long __rela_dyn_begin;
extern long __rela_dyn_end;
-extern void * __init relocate_kernel(void);
+extern unsigned long __init relocate_kernel(void);
#endif
diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
index aa64b179744f..aace7a300cd3 100644
--- a/arch/loongarch/kernel/head.S
+++ b/arch/loongarch/kernel/head.S
@@ -95,13 +95,14 @@ SYM_CODE_START(kernel_entry) # kernel entry point
PTR_LI sp, (_THREAD_SIZE - PT_SIZE)
PTR_ADD sp, sp, tp
set_saved_sp sp, t0, t1
-#endif
- /* relocate_kernel() returns the new kernel entry point */
- jr a0
- ASM_BUG()
+ /* Jump to the new kernel: new_pc = current_pc + random_offset */
+ pcaddi t0, 0
+ add.d t0, t0, a0
+ jirl zero, t0, 0xc
+#endif /* CONFIG_RANDOMIZE_BASE */
-#endif
+#endif /* CONFIG_RELOCATABLE */
bl start_kernel
ASM_BUG()
diff --git a/arch/loongarch/kernel/relocate.c b/arch/loongarch/kernel/relocate.c
index 01f94d1e3edf..6c3eff9af9fb 100644
--- a/arch/loongarch/kernel/relocate.c
+++ b/arch/loongarch/kernel/relocate.c
@@ -157,12 +157,11 @@ static inline void __init update_reloc_offset(unsigned long *addr, long random_o
*new_addr = (unsigned long)reloc_offset;
}
-void * __init relocate_kernel(void)
+unsigned long __init relocate_kernel(void)
{
unsigned long kernel_length;
unsigned long random_offset = 0;
void *location_new = _text; /* Default to original kernel start */
- void *kernel_entry = start_kernel; /* Default to original kernel entry point */
char *cmdline = early_ioremap(fw_arg1, COMMAND_LINE_SIZE); /* Boot command line is passed in fw_arg1 */
strscpy(boot_command_line, cmdline, COMMAND_LINE_SIZE);
@@ -190,9 +189,6 @@ void * __init relocate_kernel(void)
reloc_offset += random_offset;
- /* Return the new kernel's entry point */
- kernel_entry = RELOCATED_KASLR(start_kernel);
-
/* The current thread is now within the relocated kernel */
__current_thread_info = RELOCATED_KASLR(__current_thread_info);
@@ -204,7 +200,7 @@ void * __init relocate_kernel(void)
relocate_absolute(random_offset);
- return kernel_entry;
+ return random_offset;
}
/*
--
2.36.0
prev parent reply other threads:[~2023-05-12 1:59 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-12 1:57 [PATCH v3 0/4] LoongArch: Add kernel address sanitizer support Qing Zhang
2023-05-12 1:57 ` [PATCH v3 1/4] kasan: Add __HAVE_ARCH_SHADOW_MAP to support arch specific mapping Qing Zhang
2023-05-12 1:57 ` [PATCH v3 2/4] kasan: Add (pmd|pud)_init for LoongArch zero_(pud|p4d)_populate process Qing Zhang
2023-05-12 1:57 ` Qing Zhang [this message]
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