linux-arm-kernel.lists.infradead.org archive mirror
 help / color / mirror / Atom feed
From: Linus Walleij <linus.walleij@linaro.org>
To: Russell King <linux@armlinux.org.uk>,
	 Sami Tolvanen <samitolvanen@google.com>,
	Kees Cook <keescook@chromium.org>,
	 Nathan Chancellor <nathan@kernel.org>,
	 Nick Desaulniers <ndesaulniers@google.com>,
	 Ard Biesheuvel <ardb@kernel.org>, Arnd Bergmann <arnd@arndb.de>
Cc: linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev,
	 Linus Walleij <linus.walleij@linaro.org>
Subject: [PATCH v5 08/10] ARM: lib: Annotate loop delay instructions for CFI
Date: Mon, 15 Apr 2024 15:43:27 +0200	[thread overview]
Message-ID: <20240415-arm32-cfi-v5-8-ff11093eeccc@linaro.org> (raw)
In-Reply-To: <20240415-arm32-cfi-v5-0-ff11093eeccc@linaro.org>

When we annotate the loop delay code with SYM_TYPED_FUNC_START()
a function prototype signature will be emitted into the object
file above each site called from C, and the delay loop code is
using "fallthroughs" from the different assembly callbacks. This
will not work as the execution flow will run into the prototype
signatures.

Rewrite the code to use explicit branches to the other code
segments and annotate the code using SYM_TYPED_FUNC_START().

Tested on the ARM Versatile which uses the calibrated loop delay.

Tested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
 arch/arm/lib/delay-loop.S | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/arch/arm/lib/delay-loop.S b/arch/arm/lib/delay-loop.S
index 3ac05177d097..33b08ca1c242 100644
--- a/arch/arm/lib/delay-loop.S
+++ b/arch/arm/lib/delay-loop.S
@@ -5,6 +5,7 @@
  *  Copyright (C) 1995, 1996 Russell King
  */
 #include <linux/linkage.h>
+#include <linux/cfi_types.h>
 #include <asm/assembler.h>
 #include <asm/delay.h>
 
@@ -24,21 +25,26 @@
  * HZ  <= 1000
  */
 
-ENTRY(__loop_udelay)
+SYM_TYPED_FUNC_START(__loop_udelay)
 		ldr	r2, .LC1
 		mul	r0, r2, r0		@ r0 = delay_us * UDELAY_MULT
-ENTRY(__loop_const_udelay)			@ 0 <= r0 <= 0xfffffaf0
+		b	__loop_const_udelay
+SYM_FUNC_END(__loop_udelay)
+
+SYM_TYPED_FUNC_START(__loop_const_udelay)	@ 0 <= r0 <= 0xfffffaf0
 		ldr	r2, .LC0
 		ldr	r2, [r2]
 		umull	r1, r0, r2, r0		@ r0-r1 = r0 * loops_per_jiffy
 		adds	r1, r1, #0xffffffff	@ rounding up ...
 		adcs	r0, r0, r0		@ and right shift by 31
 		reteq	lr
+		b	__loop_delay
+SYM_FUNC_END(__loop_const_udelay)
 
 		.align 3
 
 @ Delay routine
-ENTRY(__loop_delay)
+SYM_TYPED_FUNC_START(__loop_delay)
 		subs	r0, r0, #1
 #if 0
 		retls	lr
@@ -58,6 +64,4 @@ ENTRY(__loop_delay)
 #endif
 		bhi	__loop_delay
 		ret	lr
-ENDPROC(__loop_udelay)
-ENDPROC(__loop_const_udelay)
-ENDPROC(__loop_delay)
+SYM_FUNC_END(__loop_delay)

-- 
2.44.0


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2024-04-15 13:44 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-15 13:43 [PATCH v5 00/10] CFI for ARM32 using LLVM Linus Walleij
2024-04-15 13:43 ` [PATCH v5 01/10] ARM: bugs: Check in the vtable instead of defined aliases Linus Walleij
2024-04-15 13:43 ` [PATCH v5 02/10] ARM: ftrace: Define ftrace_stub_graph Linus Walleij
2024-04-15 13:43 ` [PATCH v5 03/10] ARM: mm: Make tlbflush routines CFI safe Linus Walleij
2024-04-15 13:43 ` [PATCH v5 05/10] ARM: mm: Rewrite cacheflush vtables in CFI safe C Linus Walleij
2024-04-15 13:43 ` [PATCH v5 06/10] ARM: mm Type-annotate all per-processor assembly routines Linus Walleij
2024-04-15 13:43 ` [PATCH v5 07/10] ARM: mm: Define prototypes for all per-processor calls Linus Walleij
2024-04-15 13:43 ` Linus Walleij [this message]
2024-04-15 13:43 ` [PATCH v5 09/10] ARM: hw_breakpoint: Handle CFI breakpoints Linus Walleij
2024-04-15 13:43 ` [PATCH v5 10/10] ARM: Support CLANG CFI Linus Walleij
     [not found] ` <20240415-arm32-cfi-v5-4-ff11093eeccc@linaro.org>
2024-04-15 16:35   ` [PATCH v5 04/10] ARM: mm: Type-annotate all cache assembly routines Ard Biesheuvel
2024-04-16  7:38     ` Linus Walleij
2024-04-29 13:18   ` Russell King (Oracle)

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20240415-arm32-cfi-v5-8-ff11093eeccc@linaro.org \
    --to=linus.walleij@linaro.org \
    --cc=ardb@kernel.org \
    --cc=arnd@arndb.de \
    --cc=keescook@chromium.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux@armlinux.org.uk \
    --cc=llvm@lists.linux.dev \
    --cc=nathan@kernel.org \
    --cc=ndesaulniers@google.com \
    --cc=samitolvanen@google.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).