From: Deepak Gupta <debug@rivosinc.com>
To: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
llvm@lists.linux.dev
Cc: paul.walmsley@sifive.com, palmer@dabbelt.com,
aou@eecs.berkeley.edu, nathan@kernel.org,
ndesaulniers@google.com, morbo@google.com,
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falcon@tinylab.org, viro@zeniv.linux.org.uk, bhe@redhat.com,
chenjiahao16@huawei.com, hca@linux.ibm.com, arnd@arndb.de,
kent.overstreet@linux.dev, boqun.feng@gmail.com, oleg@redhat.com,
paulmck@kernel.org, broonie@kernel.org,
rick.p.edgecombe@intel.com
Subject: [RFC PATCH 05/12] riscv: fix certain indirect jumps for kernel cfi
Date: Mon, 8 Apr 2024 23:10:36 -0700 [thread overview]
Message-ID: <20240409061043.3269676-6-debug@rivosinc.com> (raw)
In-Reply-To: <20240409061043.3269676-1-debug@rivosinc.com>
Handwritten `__memset` asm routine performs certain static jumps within
function and uses `a5` to do that. This would require a landing pad
instruction at the target. Since its static jump and no memory load is
involved, use `t2` instead which is exempt from requiring a landing pad.
Signed-off-by: Deepak Gupta <debug@rivosinc.com>
---
arch/riscv/lib/memset.S | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/riscv/lib/memset.S b/arch/riscv/lib/memset.S
index 35f358e70bdb..e129ebf66986 100644
--- a/arch/riscv/lib/memset.S
+++ b/arch/riscv/lib/memset.S
@@ -56,12 +56,12 @@ SYM_FUNC_START(__memset)
/* Jump into loop body */
/* Assumes 32-bit instruction lengths */
- la a5, 3f
+ la t2, 3f
#ifdef CONFIG_64BIT
srli a4, a4, 1
#endif
- add a5, a5, a4
- jr a5
+ add t2, t2, a4
+ jr t2
3:
REG_S a1, 0(t0)
REG_S a1, SZREG(t0)
--
2.43.2
next prev parent reply other threads:[~2024-04-09 6:12 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-09 6:10 [RFC PATCH v1] riscv kernel control flow integrity Deepak Gupta
2024-04-09 6:10 ` [RFC PATCH 01/12] riscv: zicfiss / zicfilp extension csr and bit definitions Deepak Gupta
2024-04-09 6:10 ` [RFC PATCH 02/12] riscv: add landing pad for asm routines Deepak Gupta
2024-04-11 17:15 ` Sami Tolvanen
2024-04-11 17:53 ` Deepak Gupta
2024-04-11 18:33 ` Sami Tolvanen
2024-04-09 6:10 ` [RFC PATCH 03/12] riscv: after saving expected landing pad (elp), clear elp state Deepak Gupta
2024-04-09 6:10 ` [RFC PATCH 04/12] riscv: update asm call sites with label setup Deepak Gupta
2024-04-09 6:10 ` Deepak Gupta [this message]
2024-04-09 6:10 ` [RFC PATCH 06/12] scs: place init shadow stack in .shadowstack section Deepak Gupta
2024-04-09 6:10 ` [RFC PATCH 07/12] riscv/mm: prepare shadow stack for init task for kernel cfi Deepak Gupta
2024-05-12 20:12 ` Alexandre Ghiti
2024-05-13 18:59 ` Deepak Gupta
2024-04-09 6:10 ` [RFC PATCH 08/12] riscv: dynamic (zicfiss) shadow call stack support Deepak Gupta
2024-04-11 17:05 ` Sami Tolvanen
2024-04-11 17:30 ` Deepak Gupta
2024-04-11 17:47 ` Sami Tolvanen
2024-04-09 6:10 ` [RFC PATCH 09/12] scs: kernel shadow stack with hardware assistance Deepak Gupta
2024-04-09 6:10 ` [RFC PATCH 10/12] riscv/traps: Introduce software check exception Deepak Gupta
2024-04-09 6:10 ` [RFC PATCH 11/12] riscv: Kconfig & Makefile for riscv kernel control flow integrity Deepak Gupta
2024-04-09 6:10 ` [RFC PATCH 12/12] riscv: enable kernel shadow stack and landing pad enforcement Deepak Gupta
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