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From: Mark Rutland <mark.rutland@arm.com>
To: linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, will.deacon@arm.com
Cc: 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: [PATCHv5 13/21] arm64: zero GPRs upon entry from EL0
Date: Wed, 11 Jul 2018 14:56:48 +0100	[thread overview]
Message-ID: <20180711135656.20670-14-mark.rutland@arm.com> (raw)
In-Reply-To: <20180711135656.20670-1-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 22b240da949b..d1440f84668b 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 @@ alternative_cb_end
 	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 @@ alternative_cb_end
 
 	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


WARNING: multiple messages have this Message-ID (diff)
From: mark.rutland@arm.com (Mark Rutland)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCHv5 13/21] arm64: zero GPRs upon entry from EL0
Date: Wed, 11 Jul 2018 14:56:48 +0100	[thread overview]
Message-ID: <20180711135656.20670-14-mark.rutland@arm.com> (raw)
In-Reply-To: <20180711135656.20670-1-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 22b240da949b..d1440f84668b 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 @@ alternative_cb_end
 	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 @@ alternative_cb_end
 
 	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:[~2018-07-11 13:57 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-11 13:56 [PATCHv5 00/21] arm64: invoke syscalls with pt_regs Mark Rutland
2018-07-11 13:56 ` Mark Rutland
2018-07-11 13:56 ` [PATCHv5 01/21] arm64: consistently use unsigned long for thread flags Mark Rutland
2018-07-11 13:56   ` Mark Rutland
2018-07-11 13:56 ` [PATCHv5 02/21] arm64: move SCTLR_EL{1,2} assertions to <asm/sysreg.h> Mark Rutland
2018-07-11 13:56   ` [PATCHv5 02/21] arm64: move SCTLR_EL{1, 2} " Mark Rutland
2018-07-11 13:56 ` [PATCHv5 03/21] arm64: kill config_sctlr_el1() Mark Rutland
2018-07-11 13:56   ` Mark Rutland
2018-07-11 13:56 ` [PATCHv5 04/21] arm64: kill change_cpacr() Mark Rutland
2018-07-11 13:56   ` Mark Rutland
2018-07-11 13:56 ` [PATCHv5 05/21] arm64: move sve_user_{enable,disable} to <asm/fpsimd.h> Mark Rutland
2018-07-11 13:56   ` [PATCHv5 05/21] arm64: move sve_user_{enable, disable} " Mark Rutland
2018-07-11 13:56 ` [PATCHv5 06/21] arm64: remove sigreturn wrappers Mark Rutland
2018-07-11 13:56   ` Mark Rutland
2018-07-11 13:56 ` [PATCHv5 07/21] arm64: introduce syscall_fn_t Mark Rutland
2018-07-11 13:56   ` Mark Rutland
2018-07-11 13:56 ` [PATCHv5 08/21] arm64: convert raw syscall invocation to C Mark Rutland
2018-07-11 13:56   ` Mark Rutland
2018-07-11 13:56 ` [PATCHv5 09/21] arm64: convert syscall trace logic " Mark Rutland
2018-07-11 13:56   ` Mark Rutland
2018-07-11 13:56 ` [PATCHv5 10/21] arm64: convert native/compat syscall entry " Mark Rutland
2018-07-11 13:56   ` Mark Rutland
2018-07-11 13:56 ` [PATCHv5 11/21] arm64: don't restore GPRs when context tracking Mark Rutland
2018-07-11 13:56   ` Mark Rutland
2018-07-11 13:56 ` [PATCHv5 12/21] arm64: don't reload GPRs after apply_ssbd Mark Rutland
2018-07-11 13:56   ` Mark Rutland
2018-07-11 13:56 ` Mark Rutland [this message]
2018-07-11 13:56   ` [PATCHv5 13/21] arm64: zero GPRs upon entry from EL0 Mark Rutland
2018-07-11 13:56 ` [PATCHv5 14/21] arm64: drop alignment from syscall tables Mark Rutland
2018-07-11 13:56   ` Mark Rutland
2018-07-11 13:56 ` [PATCHv5 15/21] kernel: add ksys_personality() Mark Rutland
2018-07-11 13:56   ` Mark Rutland
2018-07-11 13:56 ` [PATCHv5 16/21] kernel: add kcompat_sys_{f,}statfs64() Mark Rutland
2018-07-11 13:56   ` Mark Rutland
2018-07-11 13:56 ` [PATCHv5 17/21] arm64: remove in-kernel call to sys_personality() Mark Rutland
2018-07-11 13:56   ` Mark Rutland
2018-07-11 13:56 ` [PATCHv5 18/21] arm64: use {COMPAT,}SYSCALL_DEFINE0 for sigreturn Mark Rutland
2018-07-11 13:56   ` Mark Rutland
2018-07-11 13:56 ` [PATCHv5 19/21] arm64: use SYSCALL_DEFINE6() for mmap Mark Rutland
2018-07-11 13:56   ` Mark Rutland
2018-07-11 13:56 ` [PATCHv5 20/21] arm64: convert compat wrappers to C Mark Rutland
2018-07-11 13:56   ` Mark Rutland
2018-07-11 13:56 ` [PATCHv5 21/21] arm64: implement syscall wrappers Mark Rutland
2018-07-11 13:56   ` Mark Rutland

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