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authorArd Biesheuvel <ardb@kernel.org>2021-10-05 09:15:41 +0200
committerArd Biesheuvel <ardb@kernel.org>2021-12-03 15:11:32 +0100
commit0b78f2e92d0cf722baa507c20948f1b1d6baf83d (patch)
treec923513a548ab3f8baf852fd639d8d965e45eaaf /arch/arm/lib
parentd4664b6c987f80338407889c1e3f3abe7e16be94 (diff)
ARM: call_with_stack: add unwind support
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
Diffstat (limited to 'arch/arm/lib')
-rw-r--r--arch/arm/lib/call_with_stack.S33
1 files 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)