From: Jinyang He <hejinyang@loongson.cn>
To: Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Huacai Chen <chenhc@lemote.com>,
Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 1/3] MIPS: KASLR: Correcte valid bits in apply_r_mips_26_rel
Date: Thu, 19 Nov 2020 10:29:12 +0800 [thread overview]
Message-ID: <1605752954-10368-1-git-send-email-hejinyang@loongson.cn> (raw)
Apply_r_mips_26_rel() relocates instructions like j, jal and etc. These
instructions consist of 6bits function field and 26bits address field.
The value of target_addr as follows,
=================================================================
| high 4bits | low 28bits |
=================================================================
|the high 4bits of this PC | the low 26bits of instructions << 2|
=================================================================
Thus, loc_orig and log_new both need high 4bits ranther than high 6bits.
Replace 0x3ffffff with 0xfffffff.
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
---
arch/mips/kernel/relocate.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/mips/kernel/relocate.c b/arch/mips/kernel/relocate.c
index 3d80a51..709cfa0 100644
--- a/arch/mips/kernel/relocate.c
+++ b/arch/mips/kernel/relocate.c
@@ -95,7 +95,7 @@ static int __init apply_r_mips_26_rel(u32 *loc_orig, u32 *loc_new, long offset)
/* Original target address */
target_addr <<= 2;
- target_addr += (unsigned long)loc_orig & ~0x03ffffff;
+ target_addr += (unsigned long)loc_orig & ~0x0fffffff;
/* Get the new target address */
target_addr += offset;
@@ -105,7 +105,7 @@ static int __init apply_r_mips_26_rel(u32 *loc_orig, u32 *loc_new, long offset)
return -ENOEXEC;
}
- target_addr -= (unsigned long)loc_new & ~0x03ffffff;
+ target_addr -= (unsigned long)loc_new & ~0x0fffffff;
target_addr >>= 2;
*loc_new = (*loc_new & ~0x03ffffff) | (target_addr & 0x03ffffff);
--
2.1.0
next reply other threads:[~2020-11-19 2:29 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-19 2:29 Jinyang He [this message]
2020-11-19 2:29 ` [PATCH 2/3] MIPS: Loongson64: Add KASLR support Jinyang He
2020-11-19 2:29 ` [PATCH 3/3] MIPS: KASLR: Make relocation_address can be configured Jinyang He
2020-11-19 8:06 ` Sergei Shtylyov
2020-11-19 9:31 ` Jinyang He
2020-11-19 12:45 ` Thomas Bogendoerfer
2020-11-20 2:43 ` Jinyang He
2020-11-19 12:36 ` [PATCH 1/3] MIPS: KASLR: Correcte valid bits in apply_r_mips_26_rel Thomas Bogendoerfer
2020-11-20 2:48 ` Jinyang He
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