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From: Ard Biesheuvel <ardb@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: Ard Biesheuvel <ardb@kernel.org>,
	Russell King <linux@armlinux.org.uk>,
	Arnd Bergmann <arnd@arndb.de>, Kees Cook <keescook@chromium.org>,
	Keith Packard <keithpac@amazon.com>,
	Linus Walleij <linus.walleij@linaro.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Nicolas Pitre <nico@fluxnic.net>
Subject: [PATCH v3 09/10] ARM: call_with_stack: add unwind support
Date: Sun, 17 Oct 2021 15:17:22 +0200	[thread overview]
Message-ID: <20211017131723.4034662-10-ardb@kernel.org> (raw)
In-Reply-To: <20211017131723.4034662-1-ardb@kernel.org>

Restructure the code and add the unwind annotations so that both the
frame pointer unwinder as well as the EHABI unwind info based unwinder
will be able to follow the call stack through call_with_stack().

Since GCC and Clang use different formats for the stack frame, two
methods are implemented: a GCC version that pushes fp, sp, lr and pc for
compatibility with the frame pointer unwinder, and a second version that
works with Clang, as well as with the EHABI unwinder both in ARM and
Thumb2 modes.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Keith Packard <keithpac@amazon.com>
---
 arch/arm/lib/call_with_stack.S | 33 +++++++++++++++-----
 1 file changed, 25 insertions(+), 8 deletions(-)

diff --git a/arch/arm/lib/call_with_stack.S b/arch/arm/lib/call_with_stack.S
index 28b0341ae786..0a268a6c513c 100644
--- a/arch/arm/lib/call_with_stack.S
+++ b/arch/arm/lib/call_with_stack.S
@@ -8,25 +8,42 @@
 
 #include <linux/linkage.h>
 #include <asm/assembler.h>
+#include <asm/unwind.h>
 
 /*
  * void call_with_stack(void (*fn)(void *), void *arg, void *sp)
  *
  * Change the stack to that pointed at by sp, then invoke fn(arg) with
  * the new stack.
+ *
+ * The sequence below follows the APCS frame convention for frame pointer
+ * unwinding, and implements the unwinder annotations needed by the EABI
+ * unwinder.
  */
-ENTRY(call_with_stack)
-	str	sp, [r2, #-4]!
-	str	lr, [r2, #-4]!
 
+ENTRY(call_with_stack)
+#if defined(CONFIG_UNWINDER_FRAME_POINTER) && defined(CONFIG_CC_IS_GCC)
+	mov	ip, sp
+	push	{fp, ip, lr, pc}
+	sub	fp, ip, #4
+#else
+UNWIND( .fnstart		)
+UNWIND( .save	{fpreg, lr}	)
+	push	{fpreg, lr}
+UNWIND( .setfp	fpreg, sp	)
+	mov	fpreg, sp
+#endif
 	mov	sp, r2
 	mov	r2, r0
 	mov	r0, r1
 
-	badr	lr, 1f
-	ret	r2
+	bl_r	r2
 
-1:	ldr	lr, [sp]
-	ldr	sp, [sp, #4]
-	ret	lr
+#if defined(CONFIG_UNWINDER_FRAME_POINTER) && defined(CONFIG_CC_IS_GCC)
+	ldmdb	fp, {fp, sp, pc}
+#else
+	mov	sp, fpreg
+	pop	{fpreg, pc}
+UNWIND( .fnend			)
+#endif
 ENDPROC(call_with_stack)
-- 
2.30.2


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  parent reply	other threads:[~2021-10-17 13:21 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-17 13:17 [PATCH v3 00/10] ARM: add support for IRQ stacks Ard Biesheuvel
2021-10-17 13:17 ` [PATCH v3 01/10] ARM: remove some dead code Ard Biesheuvel
2021-10-17 13:17 ` [PATCH v3 02/10] ARM: assembler: introduce bl_r and bl_m macros Ard Biesheuvel
2021-10-17 13:17 ` [PATCH v3 03/10] ARM: optimize indirect call to handle_arch_irq for v7 cores Ard Biesheuvel
2021-10-17 13:17 ` [PATCH v3 04/10] ARM: unwind: support unwinding across multiple stacks Ard Biesheuvel
2021-10-17 13:17 ` [PATCH v3 05/10] ARM: export dump_mem() to other objects Ard Biesheuvel
2021-10-17 13:17 ` [PATCH v3 06/10] ARM: unwind: dump exception stack from calling frame Ard Biesheuvel
2021-10-17 13:17 ` [PATCH v3 07/10] ARM: backtrace-clang: avoid crash on bogus frame pointer Ard Biesheuvel
2021-10-18 19:58   ` Nick Desaulniers
2021-10-17 13:17 ` [PATCH v3 08/10] ARM: implement IRQ stacks Ard Biesheuvel
2021-10-18 20:43   ` Nick Desaulniers
2021-10-18 20:59     ` Ard Biesheuvel
2021-10-18 21:03       ` Nick Desaulniers
2021-10-17 13:17 ` Ard Biesheuvel [this message]
2021-10-18 20:50   ` [PATCH v3 09/10] ARM: call_with_stack: add unwind support Nick Desaulniers
2021-10-17 13:17 ` [PATCH v3 10/10] ARM: run softirqs on the per-CPU IRQ stack Ard Biesheuvel

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