From: Alexander Graf <agraf@suse.de>
To: Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
Cc: "Tom Musta" <tommusta@gmail.com>,
qemu-ppc@nongnu.org, qemu-devel@nongnu.org,
"Andreas Färber" <afaerber@suse.de>
Subject: Re: [Qemu-devel] [PATCH v7] target-ppc: gdbstub allow byte swapping for reading/writing registers
Date: Fri, 04 Apr 2014 16:01:57 +0200 [thread overview]
Message-ID: <533EBB55.3060502@suse.de> (raw)
In-Reply-To: <1396382633-6769-1-git-send-email-tlfalcon@linux.vnet.ibm.com>
On 04/01/2014 10:03 PM, Thomas Falcon wrote:
> 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 <tlfalcon@linux.vnet.ibm.com>
> ---
> Differences from v6:
>
> Update target-ppc/translate_init.c to be compatible to latest master
> ---
> target-ppc/cpu-qom.h | 3 +
> target-ppc/gdbstub.c | 139 +++++++++++++++++++++++++++++++++++---------
> target-ppc/translate_init.c | 4 +-
> 3 files changed, 115 insertions(+), 31 deletions(-)
>
> diff --git a/target-ppc/cpu-qom.h b/target-ppc/cpu-qom.h
> index 47dc8e6..f0e2eea 100644
> --- a/target-ppc/cpu-qom.h
> +++ b/target-ppc/cpu-qom.h
> @@ -111,9 +111,12 @@ 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);
> 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_read_register_wrap(CPUState *cpu, uint8_t *buf, int reg);
> int ppc_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
> +int ppc_cpu_gdb_write_register_wrap(CPUState *cpu, uint8_t *buf, int reg);
> int ppc64_cpu_write_elf64_qemunote(WriteCoreDumpFunction f,
> CPUState *cpu, void *opaque);
> int ppc64_cpu_write_elf64_note(WriteCoreDumpFunction f, CPUState *cs,
> diff --git a/target-ppc/gdbstub.c b/target-ppc/gdbstub.c
> index 1c91090..92649ed 100644
> --- a/target-ppc/gdbstub.c
> +++ b/target-ppc/gdbstub.c
> @@ -21,6 +21,82 @@
> #include "qemu-common.h"
> #include "exec/gdbstub.h"
>
> +static int ppc_cpu_gdb_register_len(int n)
> +{
> + 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 = ppc_cpu_gdb_register_len(n);
> + if (len == 4) {
> + bswap32s((uint32_t *)mem_buf);
> + } else {
> + bswap64s((uint64_t *)mem_buf);
> + }
> +}
> +
> +int ppc_cpu_gdb_read_register_wrap(CPUState *cs, uint8_t *mem_buf, int n)
> +{
> + PowerPCCPU *cpu = POWERPC_CPU(cs);
> + CPUPPCState *env = &cpu->env;
> +
> + int len = ppc_cpu_gdb_read_register(cs, mem_buf, n);
> + if (msr_le) {
> + ppc_cpu_gdb_swap_register(mem_buf, n);
> + }
> + return len;
> +}
> +
> +int ppc_cpu_gdb_write_register_wrap(CPUState *cs, uint8_t *mem_buf, int n)
> +{
> + PowerPCCPU *cpu = POWERPC_CPU(cs);
> + CPUPPCState *env = &cpu->env;
> +
> + if (msr_le) {
> + ppc_cpu_gdb_swap_register(mem_buf, n);
> + }
> + return ppc_cpu_gdb_write_register(cs, mem_buf, n);
> +}
Now that the read_register() and write_register() functions have
awareness of the register size, we can just inline the wrappers into the
read and write functions, no?
Alex
> +
> /* 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 +108,26 @@ 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;
> - }
> 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 +135,55 @@ 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;
> + 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 (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 +191,22 @@ 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;
> }
> diff --git a/target-ppc/translate_init.c b/target-ppc/translate_init.c
> index d07e186..5c9293b 100644
> --- a/target-ppc/translate_init.c
> +++ b/target-ppc/translate_init.c
> @@ -8523,8 +8523,8 @@ static void ppc_cpu_class_init(ObjectClass *oc, void *data)
> cc->dump_state = ppc_cpu_dump_state;
> cc->dump_statistics = ppc_cpu_dump_statistics;
> cc->set_pc = ppc_cpu_set_pc;
> - cc->gdb_read_register = ppc_cpu_gdb_read_register;
> - cc->gdb_write_register = ppc_cpu_gdb_write_register;
> + cc->gdb_read_register = ppc_cpu_gdb_read_register_wrap;
> + cc->gdb_write_register = ppc_cpu_gdb_write_register_wrap;
> #ifdef CONFIG_USER_ONLY
> cc->handle_mmu_fault = ppc_cpu_handle_mmu_fault;
> #else
prev parent reply other threads:[~2014-04-04 14:02 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-01 20:03 [Qemu-devel] [PATCH v7] target-ppc: gdbstub allow byte swapping for reading/writing registers Thomas Falcon
2014-04-04 13:33 ` Tom Musta
2014-04-04 14:01 ` Alexander Graf [this message]
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