Hi all, I have noticed that accessing (more precise: writing) memory byte-by-byte on MIPS32 targets is currently borken.
Temporary array allocated for endianess swap replaces the contenst of the buffer. However, this temporary array is set-up only for hword and word accesses. This, in the case of byte access, it just (unnecessarily) overwrites buffer with random (uninitialized) value. As a fix, I propose patch attached. I will wait for comments and send PULL request from my github MIPS maintained branch, as I usually do. BR, Drasko
From b61cc1ec5d5420436fc933146d9fd4a91f79db15 Mon Sep 17 00:00:00 2001 From: Drasko DRASKOVIC <[email protected]> Date: Mon, 25 Jul 2011 14:23:35 +0200 Subject: [PATCH] mips32 : Fixed memory byte access Function mips_m4k_write_memory() does endianess byte swap, but this procedure break one byte access (temporary array overwrites content in buffer). As a fix, this endianess swap and buffer affecting is preformed only on hword and word accesses (not on byte access). --- src/target/mips_m4k.c | 51 ++++++++++++++++++++++++++---------------------- 1 files changed, 28 insertions(+), 23 deletions(-) diff --git a/src/target/mips_m4k.c b/src/target/mips_m4k.c index 350ed51..e4ab044 100644 --- a/src/target/mips_m4k.c +++ b/src/target/mips_m4k.c @@ -923,33 +923,38 @@ static int mips_m4k_write_memory(struct target *target, uint32_t address, if (((size == 4) && (address & 0x3u)) || ((size == 2) && (address & 0x1u))) return ERROR_TARGET_UNALIGNED_ACCESS; - /* mips32_..._write_mem with size 4/2 requires uint32_t/uint16_t in host */ - /* endianness, but byte array represents target endianness */ - uint8_t * t = NULL; - t = malloc(count * sizeof(uint32_t)); - if (t == NULL) + /** correct endianess if we have word or hword access */ + uint8_t *t = NULL; + if (size > 1) { - LOG_ERROR("Out of memory"); - return ERROR_FAIL; - } + /* mips32_..._write_mem with size 4/2 requires uint32_t/uint16_t in host */ + /* endianness, but byte array represents target endianness */ + t = malloc(count * sizeof(uint32_t)); + if (t == NULL) + { + LOG_ERROR("Out of memory"); + return ERROR_FAIL; + } - uint32_t i, t32; - uint16_t t16; - for(i = 0; i < (count*size); i += size) - { - switch(size) + uint32_t i, t32; + uint16_t t16; + for(i = 0; i < (count*size); i += size) { - case 4: - t32 = target_buffer_get_u32(target,&buffer[i]); - h_u32_to_le(&t[i], t32); - break; - case 2: - t16 = target_buffer_get_u16(target,&buffer[i]); - h_u16_to_le(&t[i], t16); - break; + switch(size) + { + case 4: + t32 = target_buffer_get_u32(target,&buffer[i]); + h_u32_to_le(&t[i], t32); + break; + case 2: + t16 = target_buffer_get_u16(target,&buffer[i]); + h_u16_to_le(&t[i], t16); + break; + } } + + buffer = t; } - buffer = t; /* if noDMA off, use DMAACC mode for memory write */ int retval; -- 1.7.6
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