When a correctable single bit error occurs, the driver calculates the bad_data_bit respectively the bad_ecc_bit. If there is no error in the corresponding data, the value becomes -1. With this the expected data message is calculated.
In the case of an error in the lower 32 bits or no error (-1) the right side operand of the bit-shift becomes negative which is undefined behavior. This can result in wrong and misleading messages like this: [ 311.103794] EDAC FSL_DDR MC0: Faulty Data bit: 36 [ 311.108490] EDAC FSL_DDR MC0: Expected Data / ECC: 0xffffffef_ffffffff / 0x80000059 [ 311.116135] EDAC FSL_DDR MC0: Captured Data / ECC: 0xffffffff_ffffffef / 0x59 Fix this by only calculating the expected data where the error occurred. With the fix the dmesg output looks like this: [ 311.103794] EDAC FSL_DDR MC0: Faulty Data bit: 36 [ 311.108490] EDAC FSL_DDR MC0: Expected Data / ECC: 0xffffffef_ffffffef / 0x59 [ 311.116135] EDAC FSL_DDR MC0: Captured Data / ECC: 0xffffffff_ffffffef / 0x59 Signed-off-by: Gregor Herburger <[email protected]> --- drivers/edac/fsl_ddr_edac.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/edac/fsl_ddr_edac.c b/drivers/edac/fsl_ddr_edac.c index 6d8ea226010d..4b6989cf1947 100644 --- a/drivers/edac/fsl_ddr_edac.c +++ b/drivers/edac/fsl_ddr_edac.c @@ -343,9 +343,9 @@ static void fsl_mc_check(struct mem_ctl_info *mci) fsl_mc_printk(mci, KERN_ERR, "Expected Data / ECC:\t%#8.8x_%08x / %#2.2x\n", - cap_high ^ (1 << (bad_data_bit - 32)), - cap_low ^ (1 << bad_data_bit), - syndrome ^ (1 << bad_ecc_bit)); + (bad_data_bit > 31) ? cap_high ^ (1 << (bad_data_bit - 32)) : cap_high, + (bad_data_bit <= 31) ? cap_low ^ (1 << (bad_data_bit)) : cap_low, + (bad_ecc_bit != -1) ? syndrome ^ (1 << (bad_ecc_bit)) : syndrome); } fsl_mc_printk(mci, KERN_ERR, -- 2.17.1
