From e75a3b6e89c4bce11d1885426f22262def9bd664 Mon Sep 17 00:00:00 2001 From: Andre Przywara Date: Tue, 4 Apr 2023 16:52:25 +0100 Subject: [PATCH] fix(imx8mq): fix compilation with gcc >= 12.x Starting with GCC >= 12.x the -Wall option includes -Werror=array-bounds checks. Per default GCC treats all memory accesses below 4096 as NULL, so access to ROMAPI causes the following warning: ------------ In file included from plat/imx/imx8m/imx8mq/imx8mq_bl31_setup.c:20: In function 'mmio_read_8', inlined from 'imx8mq_soc_info_init' at plat/imx/imx8m/imx8mq/imx8mq_bl31_setup.c:70:16, inlined from 'bl31_platform_setup' at plat/imx/imx8m/imx8mq/imx8mq_bl31_setup.c:206:2: include/lib/mmio.h:19:16: error: array subscript 0 is outside array bounds of 'volatile uint8_t[0]' {aka 'volatile unsigned char[]'} [-Werror=array-bounds] 19 | return *(volatile uint8_t*)addr; | ^~~~~~~~~~~~~~~~~~~~~~~~ In function 'mmio_read_8', inlined from 'imx8mq_soc_info_init' at plat/imx/imx8m/imx8mq/imx8mq_bl31_setup.c:74:16, inlined from 'bl31_platform_setup' at plat/imx/imx8m/imx8mq/imx8mq_bl31_setup.c:206:2: include/lib/mmio.h:19:16: error: array subscript 0 is outside array bounds of 'volatile uint8_t[0]' {aka 'volatile unsigned char[]'} [-Werror=array-bounds] 19 | return *(volatile uint8_t*)addr; | ^~~~~~~~~~~~~~~~~~~~~~~~ cc1: all warnings being treated as errors ------------ This comes arguably from us somewhat abusing pointers to access MMIO memory regions, which is not really covered by the C language. Replace the pointer-dereferencing mmio_read_8() with an implementation that uses inline assembly, to directly generate an 8-bit load instruction. This avoids the compiler thinking that this access is using a pointer it needs to jealously look after. Change-Id: Iab39f6f615d51d3e8a1c54a1262d1e6ec208811d Reported-by: Marco Felsch Signed-off-by: Andre Przywara --- plat/imx/imx8m/imx8mq/imx8mq_bl31_setup.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/plat/imx/imx8m/imx8mq/imx8mq_bl31_setup.c b/plat/imx/imx8m/imx8mq/imx8mq_bl31_setup.c index 661f8e291..7065a6586 100644 --- a/plat/imx/imx8m/imx8mq/imx8mq_bl31_setup.c +++ b/plat/imx/imx8m/imx8mq/imx8mq_bl31_setup.c @@ -30,6 +30,20 @@ #define TRUSTY_PARAMS_LEN_BYTES (4096*2) +/* + * Avoid the pointer dereference of the canonical mmio_read_8() implementation. + * This prevents the compiler from mis-interpreting the MMIO access as an + * illegal memory access to a very low address (the IMX ROM is mapped at 0). + */ +static uint8_t mmio_read_8_ldrb(uintptr_t address) +{ + uint8_t reg; + + __asm__ volatile ("ldrb %w0, [%1]" : "=r" (reg) : "r" (address)); + + return reg; +} + static const mmap_region_t imx_mmap[] = { MAP_REGION_FLAT(GPV_BASE, GPV_SIZE, MT_DEVICE | MT_RW), /* GPV map */ MAP_REGION_FLAT(IMX_ROM_BASE, IMX_ROM_SIZE, MT_MEMORY | MT_RO), /* ROM map */ @@ -70,11 +84,11 @@ static void imx8mq_soc_info_init(void) uint32_t ocotp_val; imx_soc_revision = mmio_read_32(IMX_ANAMIX_BASE + ANAMIX_DIGPROG); - rom_version = mmio_read_8(IMX_ROM_BASE + ROM_SOC_INFO_A0); + rom_version = mmio_read_8_ldrb(IMX_ROM_BASE + ROM_SOC_INFO_A0); if (rom_version == 0x10) return; - rom_version = mmio_read_8(IMX_ROM_BASE + ROM_SOC_INFO_B0); + rom_version = mmio_read_8_ldrb(IMX_ROM_BASE + ROM_SOC_INFO_B0); if (rom_version == 0x20) { imx_soc_revision &= ~0xff; imx_soc_revision |= rom_version; -- 2.39.5