From 432a6241bdb70b98ead8f58bbf717d3f7fe699a8 Mon Sep 17 00:00:00 2001 From: Vadzim Dambrouski Date: Mon, 19 Oct 2015 19:40:14 +0300 Subject: [PATCH] arm: add support for semihosting for ARMv7M targets If you enable CONFIG_SEMIHOSTING for STM32F429 target, you will get compile error looking like this: arch/arm/lib/semihosting.c: In function 'smh_read': {standard input}: Assembler messages: {standard input}:34: Error: invalid swi expression {standard input}:34: Error: value of 1193046 too large for field of 2 bytes at 0 scripts/Makefile.build:277: recipe for target 'arch/arm/lib/semihosting.o' failed The source of the problem is "svc #0x123456" instruction. This instruction can not be encoded using Thumb2 instruction set used by ARMv7M CPUs. ARM documentation suggests using "bkpt #0xAB" instruction instead [1]. This patch fixes compile errors and adds support for semihosting for STM32F429 or any other ARMv7M target. This change was sested on STM32F429-DISCOVERY board using OpenOCD and "smhload" u-boot command. [1] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0471c/Bgbjhiea.html Signed-off-by: Vadzim Dambrouski --- arch/arm/lib/semihosting.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/arm/lib/semihosting.c b/arch/arm/lib/semihosting.c index c3e964eabc..ed5e8e426e 100644 --- a/arch/arm/lib/semihosting.c +++ b/arch/arm/lib/semihosting.c @@ -31,6 +31,8 @@ static noinline long smh_trap(unsigned int sysnum, void *addr) register long result asm("r0"); #if defined(CONFIG_ARM64) asm volatile ("hlt #0xf000" : "=r" (result) : "0"(sysnum), "r"(addr)); +#elif defined(CONFIG_CPU_V7M) + asm volatile ("bkpt #0xAB" : "=r" (result) : "0"(sysnum), "r"(addr)); #else /* Note - untested placeholder */ asm volatile ("svc #0x123456" : "=r" (result) : "0"(sysnum), "r"(addr)); -- 2.25.1