diff options
| author | Laurent Dufour <ldufour@linux.vnet.ibm.com> | 2013-09-17 13:52:48 +0400 |
|---|---|---|
| committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2013-10-11 09:53:16 +0400 |
| commit | dbd0c5d5296f291a5c3affee4fbdde254632ffca (patch) | |
| tree | 9b622a06c6dcd9150b24b27435ce5fe000b71749 /arch | |
| parent | e48673360b8b113ca83dc3a45e02ad37fdf9f2d0 (diff) | |
| download | linux-dbd0c5d5296f291a5c3affee4fbdde254632ffca.tar.xz | |
powerpc: prom_init exception when updating core value
Since the CPU is generating an exception when accessing unaligned word, and
as this exception is not yet handled when running prom_init, data should be
copied from the architecture vector byte per byte.
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/powerpc/kernel/prom_init.c | 28 |
1 files changed, 22 insertions, 6 deletions
diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c index 5fe2842e8bab..cb64a6e1dc51 100644 --- a/arch/powerpc/kernel/prom_init.c +++ b/arch/powerpc/kernel/prom_init.c @@ -858,7 +858,8 @@ static void __init prom_send_capabilities(void) { ihandle root; prom_arg_t ret; - __be32 *cores; + u32 cores; + unsigned char *ptcores; root = call_prom("open", 1, 1, ADDR("/")); if (root != 0) { @@ -868,15 +869,30 @@ static void __init prom_send_capabilities(void) * (we assume this is the same for all cores) and use it to * divide NR_CPUS. */ - cores = (__be32 *)&ibm_architecture_vec[IBM_ARCH_VEC_NRCORES_OFFSET]; - if (be32_to_cpup(cores) != NR_CPUS) { + + /* The core value may start at an odd address. If such a word + * access is made at a cache line boundary, this leads to an + * exception which may not be handled at this time. + * Forcing a per byte access to avoid exception. + */ + ptcores = &ibm_architecture_vec[IBM_ARCH_VEC_NRCORES_OFFSET]; + cores = 0; + cores |= ptcores[0] << 24; + cores |= ptcores[1] << 16; + cores |= ptcores[2] << 8; + cores |= ptcores[3]; + if (cores != NR_CPUS) { prom_printf("WARNING ! " "ibm_architecture_vec structure inconsistent: %lu!\n", - be32_to_cpup(cores)); + cores); } else { - *cores = cpu_to_be32(DIV_ROUND_UP(NR_CPUS, prom_count_smt_threads())); + cores = DIV_ROUND_UP(NR_CPUS, prom_count_smt_threads()); prom_printf("Max number of cores passed to firmware: %lu (NR_CPUS = %lu)\n", - be32_to_cpup(cores), NR_CPUS); + cores, NR_CPUS); + ptcores[0] = (cores >> 24) & 0xff; + ptcores[1] = (cores >> 16) & 0xff; + ptcores[2] = (cores >> 8) & 0xff; + ptcores[3] = cores & 0xff; } /* try calling the ibm,client-architecture-support method */ |