Am 04.04.2014 22:23, schrieb Thomas Falcon:
> This patch allows registers to be properly read from and written to
> when using the gdbstub to debug a ppc guest running in little
> endian mode. It accomplishes this goal by byte swapping the values of
> any registers if the MSR:LE value is set.
>
> Signed-off-by: Thomas Falcon <tlfal...@linux.vnet.ibm.com>
> ---
> Differences for v7:
>
> Inlined the register_read() and register_write() wrapper functions
> ---
> target-ppc/cpu-qom.h | 1 +
> target-ppc/gdbstub.c | 125
> +++++++++++++++++++++++++++++++++++++--------------
> 2 files changed, 92 insertions(+), 34 deletions(-)
>
> diff --git a/target-ppc/cpu-qom.h b/target-ppc/cpu-qom.h
> index 47dc8e6..aab4977 100644
> --- a/target-ppc/cpu-qom.h
> +++ b/target-ppc/cpu-qom.h
> @@ -111,6 +111,7 @@ void ppc_cpu_dump_state(CPUState *cpu, FILE *f,
> fprintf_function cpu_fprintf,
> int flags);
> void ppc_cpu_dump_statistics(CPUState *cpu, FILE *f,
> fprintf_function cpu_fprintf, int flags);
> +void ppc_cpu_gdb_swap_register(uint8_t *buf, int reg, int len);
This is only ever used in gdbstub.c. Can we please keep it static there
to avoid a full ppc*-softmmu rebuild?
> hwaddr ppc_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
> int ppc_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
> int ppc_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
> diff --git a/target-ppc/gdbstub.c b/target-ppc/gdbstub.c
> index 1c91090..594dd08 100644
> --- a/target-ppc/gdbstub.c
> +++ b/target-ppc/gdbstub.c
> @@ -21,6 +21,58 @@
> #include "qemu-common.h"
> #include "exec/gdbstub.h"
>
> +static int ppc_cpu_gdb_register_len(int n)
Nitpick: Since these two functions do not operate on the CPU, you could
just use ppc_gdb_* rather than ppc_cpu_gdb_*.
> +{
> + switch (n) {
> + case 0 ... 31:
> + /* gprs */
> + return sizeof(target_ulong);
> + case 32 ... 63:
> + /* fprs */
> + if (gdb_has_xml) {
> + return 0;
> + }
> + return 8;
> + case 66:
> + /* cr */
> + return 4;
> + case 64:
> + /* nip */
> + case 65:
> + /* msr */
> + case 67:
> + /* lr */
> + case 68:
> + /* ctr */
> + case 69:
> + /* xer */
> + return sizeof(target_ulong);
> + case 70:
> + /* fpscr */
> + if (gdb_has_xml) {
> + return 0;
> + }
> + return sizeof(target_ulong);
> + default:
> + return 0;
> + }
> +}
> +
> +
> +/* The following functions are used to ensure the correct
> + * transfer of registers between a little endian ppc target
> + * and a big endian host by checking the LE bit in the Machine State Register
> + */
> +
> +void ppc_cpu_gdb_swap_register(uint8_t *mem_buf, int n, int len)
> +{
> + if (len == 4) {
> + bswap32s((uint32_t *)mem_buf);
> + } else {
> + bswap64s((uint64_t *)mem_buf);
> + }
This logic assumes that len can only be either 4 or 8. Please use an
explicit len == 8 comparison and g_assert_not_reached() on unhandled len
values.
> +}
> +
> /* Old gdb always expects FP registers. Newer (xml-aware) gdb only
> * expects whatever the target description contains. Due to a
> * historical mishap the FP registers appear in between core integer
> @@ -32,23 +84,26 @@ int ppc_cpu_gdb_read_register(CPUState *cs, uint8_t
> *mem_buf, int n)
> {
> PowerPCCPU *cpu = POWERPC_CPU(cs);
> CPUPPCState *env = &cpu->env;
> + int r = ppc_cpu_gdb_register_len(n);
> +
> + if (!r) {
> + return r;
> + }
>
> if (n < 32) {
> /* gprs */
> - return gdb_get_regl(mem_buf, env->gpr[n]);
> + gdb_get_regl(mem_buf, env->gpr[n]);
> } else if (n < 64) {
> /* fprs */
> - if (gdb_has_xml) {
> - return 0;
> - }
I stumbled over dropping this not being related to Little Endian or
being mentioned in the commit message. Maybe mention that this is
replaced by ..._register_len() and returning early?
Otherwise looking much more to my taste now. :)
Regards,
Andreas
> stfq_p(mem_buf, env->fpr[n-32]);
> - return 8;
> } else {
> switch (n) {
> case 64:
> - return gdb_get_regl(mem_buf, env->nip);
> + gdb_get_regl(mem_buf, env->nip);
> + break;
> case 65:
> - return gdb_get_regl(mem_buf, env->msr);
> + gdb_get_regl(mem_buf, env->msr);
> + break;
> case 66:
> {
> uint32_t cr = 0;
> @@ -56,50 +111,55 @@ int ppc_cpu_gdb_read_register(CPUState *cs, uint8_t
> *mem_buf, int n)
> for (i = 0; i < 8; i++) {
> cr |= env->crf[i] << (32 - ((i + 1) * 4));
> }
> - return gdb_get_reg32(mem_buf, cr);
> + gdb_get_reg32(mem_buf, cr);
> + break;
> }
> case 67:
> - return gdb_get_regl(mem_buf, env->lr);
> + gdb_get_regl(mem_buf, env->lr);
> + break;
> case 68:
> - return gdb_get_regl(mem_buf, env->ctr);
> + gdb_get_regl(mem_buf, env->ctr);
> + break;
> case 69:
> - return gdb_get_regl(mem_buf, env->xer);
> + gdb_get_regl(mem_buf, env->xer);
> + break;
> case 70:
> - {
> - if (gdb_has_xml) {
> - return 0;
> - }
> - return gdb_get_reg32(mem_buf, env->fpscr);
> - }
> + gdb_get_reg32(mem_buf, env->fpscr);
> + break;
> }
> }
> - return 0;
> + if (msr_le) {
> + ppc_cpu_gdb_swap_register(mem_buf, n, r);
> + }
> + return r;
> }
>
> int ppc_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n)
> {
> PowerPCCPU *cpu = POWERPC_CPU(cs);
> CPUPPCState *env = &cpu->env;
> + int r = ppc_cpu_gdb_register_len(n);
>
> + if (!r) {
> + return r;
> + }
> + if (msr_le) {
> + ppc_cpu_gdb_swap_register(mem_buf, n, r);
> + }
> if (n < 32) {
> /* gprs */
> env->gpr[n] = ldtul_p(mem_buf);
> - return sizeof(target_ulong);
> } else if (n < 64) {
> /* fprs */
> - if (gdb_has_xml) {
> - return 0;
> - }
> env->fpr[n-32] = ldfq_p(mem_buf);
> - return 8;
> } else {
> switch (n) {
> case 64:
> env->nip = ldtul_p(mem_buf);
> - return sizeof(target_ulong);
> + break;
> case 65:
> ppc_store_msr(env, ldtul_p(mem_buf));
> - return sizeof(target_ulong);
> + break;
> case 66:
> {
> uint32_t cr = ldl_p(mem_buf);
> @@ -107,25 +167,22 @@ int ppc_cpu_gdb_write_register(CPUState *cs, uint8_t
> *mem_buf, int n)
> for (i = 0; i < 8; i++) {
> env->crf[i] = (cr >> (32 - ((i + 1) * 4))) & 0xF;
> }
> - return 4;
> + break;
> }
> case 67:
> env->lr = ldtul_p(mem_buf);
> - return sizeof(target_ulong);
> + break;
> case 68:
> env->ctr = ldtul_p(mem_buf);
> - return sizeof(target_ulong);
> + break;
> case 69:
> env->xer = ldtul_p(mem_buf);
> - return sizeof(target_ulong);
> + break;
> case 70:
> /* fpscr */
> - if (gdb_has_xml) {
> - return 0;
> - }
> store_fpscr(env, ldtul_p(mem_buf), 0xffffffff);
> - return sizeof(target_ulong);
> + break;
> }
> }
> - return 0;
> + return r;
> }
>
--
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