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From: Mark Rutland <mark.rutland@arm.com>
To: linux-arm-kernel@lists.infradead.org, will.deacon@arm.com
Cc: linux-kernel@vger.kernel.org, catalin.marinas@arm.com,
	dave.martin@arm.com, hch@infradead.org, james.morse@arm.com,
	linux@dominikbrodowski.net, linux-fsdevel@vger.kernel.org,
	marc.zyngier@arm.com, mark.rutland@arm.com,
	viro@zeniv.linux.org.uk
Subject: [PATCHv4 12/19] arm64: zero GPRs upon entry from EL0
Date: Mon,  2 Jul 2018 12:04:08 +0100	[thread overview]
Message-ID: <20180702110415.10465-13-mark.rutland@arm.com> (raw)
In-Reply-To: <20180702110415.10465-1-mark.rutland@arm.com>

We can zero GPRs x0 - x29 upon entry from EL0 to make it harder for
userspace to control values consumed by speculative gadgets.

We don't blat x30, since this is stashed much later, and we'll blat it
before invoking C code.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
 arch/arm64/kernel/entry.S | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 728bc7cc5bbb..6b7789d72064 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -53,6 +53,12 @@
 #endif
 	.endm
 
+	.macro	clear_gp_regs
+	.irp	n,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29
+	mov	x\n, xzr
+	.endr
+	.endm
+
 /*
  * Bad Abort numbers
  *-----------------
@@ -169,6 +175,7 @@ skip_apply_ssbd\@:
 	stp	x28, x29, [sp, #16 * 14]
 
 	.if	\el == 0
+	clear_gp_regs
 	mrs	x21, sp_el0
 	ldr_this_cpu	tsk, __entry_task, x20	// Ensure MDSCR_EL1.SS is clear,
 	ldr	x19, [tsk, #TSK_TI_FLAGS]	// since we can unmask debug
@@ -176,7 +183,6 @@ skip_apply_ssbd\@:
 
 	apply_ssbd 1, x22, x23
 
-	mov	x29, xzr			// fp pointed to user-space
 	.else
 	add	x21, sp, #S_FRAME_SIZE
 	get_thread_info tsk
-- 
2.11.0


  parent reply	other threads:[~2018-07-02 11:06 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-02 11:03 [PATCHv4 00/19] arm64: invoke syscalls with pt_regs Mark Rutland
2018-07-02 11:03 ` [PATCHv4 01/19] arm64: consistently use unsigned long for thread flags Mark Rutland
2018-07-02 11:03 ` [PATCHv4 02/19] arm64: move SCTLR_EL{1,2} assertions to <asm/sysreg.h> Mark Rutland
2018-07-02 11:03 ` [PATCHv4 03/19] arm64: kill config_sctlr_el1() Mark Rutland
2018-07-02 11:04 ` [PATCHv4 04/19] arm64: kill change_cpacr() Mark Rutland
2018-07-02 11:04 ` [PATCHv4 05/19] arm64: move sve_user_{enable,disable} to <asm/fpsimd.h> Mark Rutland
2018-07-02 11:04 ` [PATCHv4 06/19] arm64: remove sigreturn wrappers Mark Rutland
2018-07-02 11:04 ` [PATCHv4 07/19] arm64: convert raw syscall invocation to C Mark Rutland
2018-07-02 11:04 ` [PATCHv4 08/19] arm64: convert syscall trace logic " Mark Rutland
2018-07-02 11:04 ` [PATCHv4 09/19] arm64: convert native/compat syscall entry " Mark Rutland
2018-07-02 11:04 ` [PATCHv4 10/19] arm64: don't restore GPRs when context tracking Mark Rutland
2018-07-02 11:04 ` [PATCHv4 11/19] arm64: don't reload GPRs after apply_ssbd Mark Rutland
2018-07-06 16:38   ` Will Deacon
2018-07-09 14:21     ` Mark Rutland
2018-07-10 10:37       ` Dave Martin
2018-07-10 17:33         ` Will Deacon
2018-07-11  9:46           ` Mark Rutland
2018-07-02 11:04 ` Mark Rutland [this message]
2018-07-02 11:04 ` [PATCHv4 13/19] kernel: add ksys_personality() Mark Rutland
2018-07-02 11:04 ` [PATCHv4 14/19] kernel: add kcompat_sys_{f,}statfs64() Mark Rutland
2018-07-02 11:04 ` [PATCHv4 15/19] arm64: remove in-kernel call to sys_personality() Mark Rutland
2018-07-02 11:04 ` [PATCHv4 16/19] arm64: use {COMPAT,}SYSCALL_DEFINE0 for sigreturn Mark Rutland
2018-07-02 11:04 ` [PATCHv4 17/19] arm64: use SYSCALL_DEFINE6() for mmap Mark Rutland
2018-07-02 11:04 ` [PATCHv4 18/19] arm64: convert compat wrappers to C Mark Rutland
2018-07-02 11:04 ` [PATCHv4 19/19] arm64: implement syscall wrappers Mark Rutland
2018-07-06 16:42 ` [PATCHv4 00/19] arm64: invoke syscalls with pt_regs Will Deacon
2018-07-10 10:39 ` Will Deacon
2018-07-11 10:47   ` Mark Rutland
2018-07-11 12:27     ` Will Deacon

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