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From: Oliver Swede <oli.swede@arm.com>
To: catalin.marinas@arm.com, will@kernel.org
Cc: robin.murphy@arm.com, linux-arm-kernel@lists.indradead.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v5 10/14] arm64: usercopy: Store the arguments on stack
Date: Mon, 14 Sep 2020 15:09:54 +0000	[thread overview]
Message-ID: <20200914150958.2200-11-oli.swede@arm.com> (raw)
In-Reply-To: <20200914150958.2200-1-oli.swede@arm.com>

Use the stack to preserve the initial arguments to the usercopy
functions before the copy routine modifies the relevant registers.
The values in x0 (dst), x1 (src) and x2 (count) may be modified
in the code paths for large copy sizes, and saving them before
the copy begins enables restoration by the fixup routines to
ensure they have the required information to backtrack effectively.

The stack is used instead of other general-purpose registers due to
resource constraints as all scratch registers x0-x17 defined by the
PCS in the ABI are utilized by the imported copy routine.

The stack pointer is restored to its initial position either from
the fixup code in the case of a fault, or at the end of the copy
algorithm otherwise. The .Luaccess_finish directive is also moved
to copy_template_user.S as the code is common to all usercopy
functions.

Signed-off-by: Oliver Swede <oli.swede@arm.com>
---
 arch/arm64/lib/copy_from_user.S     | 3 ---
 arch/arm64/lib/copy_in_user.S       | 3 ---
 arch/arm64/lib/copy_template_user.S | 6 ++++++
 arch/arm64/lib/copy_to_user.S       | 3 ---
 arch/arm64/lib/copy_user_fixup.S    | 1 +
 5 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S
index fa319f27a42b..cd3042e98394 100644
--- a/arch/arm64/lib/copy_from_user.S
+++ b/arch/arm64/lib/copy_from_user.S
@@ -110,9 +110,6 @@
 
 SYM_FUNC_START(__arch_copy_from_user)
 #include "copy_template_user.S"
-.Luaccess_finish:
-	mov	x0, #0
-	ret
 SYM_FUNC_END(__arch_copy_from_user)
 EXPORT_SYMBOL(__arch_copy_from_user)
 #include "copy_user_fixup.S"
diff --git a/arch/arm64/lib/copy_in_user.S b/arch/arm64/lib/copy_in_user.S
index 6b9bb6091dd8..fe035e513b34 100644
--- a/arch/arm64/lib/copy_in_user.S
+++ b/arch/arm64/lib/copy_in_user.S
@@ -117,9 +117,6 @@
 
 SYM_FUNC_START(__arch_copy_in_user)
 #include "copy_template_user.S"
-.Luaccess_finish:
-	mov	x0, #0
-	ret
 SYM_FUNC_END(__arch_copy_in_user)
 EXPORT_SYMBOL(__arch_copy_in_user)
 #include "copy_user_fixup.S"
diff --git a/arch/arm64/lib/copy_template_user.S b/arch/arm64/lib/copy_template_user.S
index 3db24dcdab05..1d13daf314b0 100644
--- a/arch/arm64/lib/copy_template_user.S
+++ b/arch/arm64/lib/copy_template_user.S
@@ -21,4 +21,10 @@
 L(copy_non_uao):
 #undef L
 #define L(l) .Lnuao ## l
+	str     x2, [sp, #-16]!		// count
+	stp     x0, x1, [sp, #-16]!	// dstin, src
 #include "copy_template.S"
+.Luaccess_finish:
+	add	sp, sp, 32
+	mov	x0, #0
+	ret
diff --git a/arch/arm64/lib/copy_to_user.S b/arch/arm64/lib/copy_to_user.S
index 23af6af254da..de0af211b3ba 100644
--- a/arch/arm64/lib/copy_to_user.S
+++ b/arch/arm64/lib/copy_to_user.S
@@ -110,9 +110,6 @@
 
 SYM_FUNC_START(__arch_copy_to_user)
 #include "copy_template_user.S"
-.Luaccess_finish:
-	mov	x0, #0
-	ret
 SYM_FUNC_END(__arch_copy_to_user)
 EXPORT_SYMBOL(__arch_copy_to_user)
 #include "copy_user_fixup.S"
diff --git a/arch/arm64/lib/copy_user_fixup.S b/arch/arm64/lib/copy_user_fixup.S
index 32fae9e2e799..a528b7d7d1bd 100644
--- a/arch/arm64/lib/copy_user_fixup.S
+++ b/arch/arm64/lib/copy_user_fixup.S
@@ -10,5 +10,6 @@ addr	.req	x15
 	ccmp addr, srcend, #0x0, ge
 	csel x0, srcend, dstend, lt
 	sub x0, x0, addr
+	add sp, sp, 32
 	ret
 
-- 
2.17.1


  parent reply	other threads:[~2020-09-14 15:14 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-14 15:09 [PATCH v5 00/14] Optimise and update memcpy, user copy and string routines Oliver Swede
2020-09-14 15:09 ` [PATCH v5 01/14] arm64: Allow passing fault address to fixup handlers Oliver Swede
2020-09-14 15:09 ` [PATCH v5 02/14] arm64: kprobes: Drop open-coded exception fixup Oliver Swede
2020-09-14 15:09 ` [PATCH v5 03/14] arm64: Import latest version of Cortex Strings' memcmp Oliver Swede
2020-09-14 15:09 ` [PATCH v5 04/14] arm64: Import latest version of Cortex Strings' memmove Oliver Swede
2020-09-14 15:09 ` [PATCH v5 05/14] arm64: Import latest version of Cortex Strings' strcmp Oliver Swede
2020-09-14 15:09 ` [PATCH v5 06/14] arm64: Import latest version of Cortex Strings' strlen Oliver Swede
2020-09-14 15:09 ` [PATCH v5 07/14] arm64: Import latest version of Cortex Strings' strncmp Oliver Swede
2020-09-14 15:09 ` [PATCH v5 08/14] arm64: Import latest optimization of memcpy Oliver Swede
2021-06-01 10:03   ` Sunil Kovvuri
2021-06-01 12:06     ` Robin Murphy
2021-06-01 12:31       ` Sunil Kovvuri
2021-06-03  8:45       ` David Laight
2020-09-14 15:09 ` [PATCH v5 09/14] arm64: Tidy up _asm_extable_faultaddr usage Oliver Swede
2020-09-14 15:09 ` Oliver Swede [this message]
2020-09-14 15:09 ` [PATCH v5 11/14] arm64: usercopy: Check for overlapping buffers in fixup Oliver Swede
2020-09-14 15:09 ` [PATCH v5 12/14] arm64: usercopy: Add intermediate fixup routine Oliver Swede
2020-09-14 15:09 ` [PATCH v5 13/14] arm64: usercopy: Add conclusive " Oliver Swede
2020-09-14 15:09 ` [PATCH v5 14/14] arm64: usercopy: Reduce overhead in fixup Oliver Swede
2020-09-14 15:17 [PATCH v5 00/14] Optimise and update memcpy, user copy and string routines Oliver Swede
2020-09-14 15:17 ` [PATCH v5 10/14] arm64: usercopy: Store the arguments on stack Oliver Swede

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