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ARM: call_with_stack: add unwind support

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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>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
This commit is contained in:
Ard Biesheuvel 2021-10-05 09:15:41 +02:00
parent d4664b6c98
commit 0b78f2e92d
1 changed files with 25 additions and 8 deletions
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33
arch/arm/lib/call_with_stack.S
View file

@ -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)