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Message-Id: <1606298838-7006-1-git-send-email-hejinyang@loongson.cn> Date: Wed, 25 Nov 2020 18:07:18 +0800 From: Jinyang He <hejinyang@...ngson.cn> To: Thomas Bogendoerfer <tsbogend@...ha.franken.de> Cc: linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org Subject: [PATCH v2 1/2] MIPS: KASLR: Correcte valid bits in apply_r_mips_26_rel() 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 rather than high 6bits. Signed-off-by: Jinyang He <hejinyang@...ngson.cn> --- v2: Replace ~0x0fffffff with 0xf0000000 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..8561c7a 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 & 0xf0000000; /* 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 & 0xf0000000; target_addr >>= 2; *loc_new = (*loc_new & ~0x03ffffff) | (target_addr & 0x03ffffff); -- 2.1.0
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