gdbstub: extend GByteArray to read register helpers

Instead of passing a pointer to memory now just extend the GByteArray
to all the read register helpers. They can then safely append their
data through the normal way. We don't bother with this abstraction for
write registers as we have already ensured the buffer being copied
from is the correct size.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Damien Hedde <damien.hedde@greensocs.com>

Message-Id: <20200316172155.971-15-alex.bennee@linaro.org>

gdbstub.c

@@ -319,8 +319,8 @@ static int gdb_signal_to_target (int sig)
 typedef struct GDBRegisterState {
     int base_reg;
     int num_regs;
-    gdb_reg_cb get_reg;
-    gdb_reg_cb set_reg;
+    gdb_get_reg_cb get_reg;
+    gdb_set_reg_cb set_reg;
     const char *xml;
     struct GDBRegisterState *next;
 } GDBRegisterState;
@@ -905,19 +905,19 @@ static const char *get_feature_xml(const char *p, const char **newp,
     return name ? xml_builtin[i][1] : NULL;
 }
 
-static int gdb_read_register(CPUState *cpu, uint8_t *mem_buf, int reg)
+static int gdb_read_register(CPUState *cpu, GByteArray *buf, int reg)
 {
     CPUClass *cc = CPU_GET_CLASS(cpu);
     CPUArchState *env = cpu->env_ptr;
     GDBRegisterState *r;
 
     if (reg < cc->gdb_num_core_regs) {
-        return cc->gdb_read_register(cpu, mem_buf, reg);
+        return cc->gdb_read_register(cpu, buf, reg);
     }
 
     for (r = cpu->gdb_regs; r; r = r->next) {
         if (r->base_reg <= reg && reg < r->base_reg + r->num_regs) {
-            return r->get_reg(env, mem_buf, reg - r->base_reg);
+            return r->get_reg(env, buf, reg - r->base_reg);
         }
     }
     return 0;
@@ -948,7 +948,7 @@ static int gdb_write_register(CPUState *cpu, uint8_t *mem_buf, int reg)
  */
 
 void gdb_register_coprocessor(CPUState *cpu,
-                              gdb_reg_cb get_reg, gdb_reg_cb set_reg,
+                              gdb_get_reg_cb get_reg, gdb_set_reg_cb set_reg,
                               int num_regs, const char *xml, int g_pos)
 {
     GDBRegisterState *s;
@@ -1739,7 +1739,7 @@ static void handle_get_reg(GdbCmdContext *gdb_ctx, void *user_ctx)
     }
 
     reg_size = gdb_read_register(gdbserver_state.g_cpu,
-                                 gdbserver_state.mem_buf->data,
+                                 gdbserver_state.mem_buf,
                                  gdb_ctx->params[0].val_ull);
     if (!reg_size) {
         put_packet("E14");
@@ -1832,14 +1832,14 @@ static void handle_read_all_regs(GdbCmdContext *gdb_ctx, void *user_ctx)
     target_ulong addr, len;
 
     cpu_synchronize_state(gdbserver_state.g_cpu);
+    g_byte_array_set_size(gdbserver_state.mem_buf, 0);
     len = 0;
     for (addr = 0; addr < gdbserver_state.g_cpu->gdb_num_g_regs; addr++) {
         len += gdb_read_register(gdbserver_state.g_cpu,
-                                 gdbserver_state.mem_buf->data + len,
+                                 gdbserver_state.mem_buf,
                                  addr);
     }
-    /* FIXME: This is after the fact sizing */
-    g_byte_array_set_size(gdbserver_state.mem_buf, len);
+    g_assert(len == gdbserver_state.mem_buf->len);
 
     memtohex(gdbserver_state.str_buf, gdbserver_state.mem_buf->data, len);
     put_strbuf();

hw/core/cpu.c

@@ -177,7 +177,7 @@ static int cpu_common_write_elf64_note(WriteCoreDumpFunction f,
 }
 
 
-static int cpu_common_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg)
+static int cpu_common_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg)
 {
     return 0;
 }

include/exec/gdbstub.h

@@ -68,53 +68,76 @@ void gdb_signalled(CPUArchState *, int);
 void gdbserver_fork(CPUState *);
 #endif
 /* Get or set a register.  Returns the size of the register.  */
-typedef int (*gdb_reg_cb)(CPUArchState *env, uint8_t *buf, int reg);
+typedef int (*gdb_get_reg_cb)(CPUArchState *env, GByteArray *buf, int reg);
+typedef int (*gdb_set_reg_cb)(CPUArchState *env, uint8_t *buf, int reg);
 void gdb_register_coprocessor(CPUState *cpu,
-                              gdb_reg_cb get_reg, gdb_reg_cb set_reg,
+                              gdb_get_reg_cb get_reg, gdb_set_reg_cb set_reg,
                               int num_regs, const char *xml, int g_pos);
 
-/* The GDB remote protocol transfers values in target byte order.  This means
- * we can use the raw memory access routines to access the value buffer.
- * Conveniently, these also handle the case where the buffer is mis-aligned.
+/*
+ * The GDB remote protocol transfers values in target byte order. As
+ * the gdbstub may be batching up several register values we always
+ * append to the array.
  */
 
-static inline int gdb_get_reg8(uint8_t *mem_buf, uint8_t val)
+static inline int gdb_get_reg8(GByteArray *buf, uint8_t val)
 {
-    stb_p(mem_buf, val);
+    g_byte_array_append(buf, &val, 1);
     return 1;
 }
 
-static inline int gdb_get_reg16(uint8_t *mem_buf, uint16_t val)
+static inline int gdb_get_reg16(GByteArray *buf, uint16_t val)
 {
-    stw_p(mem_buf, val);
+    uint16_t to_word = tswap16(val);
+    g_byte_array_append(buf, (uint8_t *) &to_word, 2);
     return 2;
 }
 
-static inline int gdb_get_reg32(uint8_t *mem_buf, uint32_t val)
+static inline int gdb_get_reg32(GByteArray *buf, uint32_t val)
 {
-    stl_p(mem_buf, val);
+    uint32_t to_long = tswap32(val);
+    g_byte_array_append(buf, (uint8_t *) &to_long, 4);
     return 4;
 }
 
-static inline int gdb_get_reg64(uint8_t *mem_buf, uint64_t val)
+static inline int gdb_get_reg64(GByteArray *buf, uint64_t val)
 {
-    stq_p(mem_buf, val);
+    uint64_t to_quad = tswap64(val);
+    g_byte_array_append(buf, (uint8_t *) &to_quad, 8);
     return 8;
 }
 
-static inline int gdb_get_reg128(uint8_t *mem_buf, uint64_t val_hi,
+static inline int gdb_get_reg128(GByteArray *buf, uint64_t val_hi,
                                  uint64_t val_lo)
 {
+    uint64_t to_quad;
 #ifdef TARGET_WORDS_BIGENDIAN
-    stq_p(mem_buf, val_hi);
-    stq_p(mem_buf + 8, val_lo);
+    to_quad = tswap64(val_hi);
+    g_byte_array_append(buf, (uint8_t *) &to_quad, 8);
+    to_quad = tswap64(val_lo);
+    g_byte_array_append(buf, (uint8_t *) &to_quad, 8);
 #else
-    stq_p(mem_buf, val_lo);
-    stq_p(mem_buf + 8, val_hi);
+    to_quad = tswap64(val_lo);
+    g_byte_array_append(buf, (uint8_t *) &to_quad, 8);
+    to_quad = tswap64(val_hi);
+    g_byte_array_append(buf, (uint8_t *) &to_quad, 8);
 #endif
     return 16;
 }
 
+/**
+ * gdb_get_reg_ptr: get pointer to start of last element
+ * @len: length of element
+ *
+ * This is a helper function to extract the pointer to the last
+ * element for additional processing. Some front-ends do additional
+ * dynamic swapping of the elements based on CPU state.
+ */
+static inline uint8_t * gdb_get_reg_ptr(GByteArray *buf, int len)
+{
+    return buf->data + buf->len - len;
+}
+
 #if TARGET_LONG_BITS == 64
 #define gdb_get_regl(buf, val) gdb_get_reg64(buf, val)
 #define ldtul_p(addr) ldq_p(addr)

include/hw/core/cpu.h

@@ -195,7 +195,7 @@ typedef struct CPUClass {
     hwaddr (*get_phys_page_attrs_debug)(CPUState *cpu, vaddr addr,
                                         MemTxAttrs *attrs);
     int (*asidx_from_attrs)(CPUState *cpu, MemTxAttrs attrs);
-    int (*gdb_read_register)(CPUState *cpu, uint8_t *buf, int reg);
+    int (*gdb_read_register)(CPUState *cpu, GByteArray *buf, int reg);
     int (*gdb_write_register)(CPUState *cpu, uint8_t *buf, int reg);
     bool (*debug_check_watchpoint)(CPUState *cpu, CPUWatchpoint *wp);
     void (*debug_excp_handler)(CPUState *cpu);

target/alpha/cpu.h

@@ -280,7 +280,7 @@ void alpha_cpu_do_interrupt(CPUState *cpu);
 bool alpha_cpu_exec_interrupt(CPUState *cpu, int int_req);
 void alpha_cpu_dump_state(CPUState *cs, FILE *f, int flags);
 hwaddr alpha_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
-int alpha_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int alpha_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int alpha_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 void alpha_cpu_do_unaligned_access(CPUState *cpu, vaddr addr,
                                    MMUAccessType access_type,

target/alpha/gdbstub.c

@@ -21,7 +21,7 @@
 #include "cpu.h"
 #include "exec/gdbstub.h"
 
-int alpha_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int alpha_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     AlphaCPU *cpu = ALPHA_CPU(cs);
     CPUAlphaState *env = &cpu->env;

target/arm/cpu.h

@@ -968,7 +968,7 @@ bool arm_cpu_exec_interrupt(CPUState *cpu, int int_req);
 hwaddr arm_cpu_get_phys_page_attrs_debug(CPUState *cpu, vaddr addr,
                                          MemTxAttrs *attrs);
 
-int arm_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int arm_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int arm_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 
 /* Dynamically generates for gdb stub an XML description of the sysregs from
@@ -988,7 +988,7 @@ int arm_cpu_write_elf32_note(WriteCoreDumpFunction f, CPUState *cs,
                              int cpuid, void *opaque);
 
 #ifdef TARGET_AARCH64
-int aarch64_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int aarch64_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int aarch64_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 void aarch64_sve_narrow_vq(CPUARMState *env, unsigned vq);
 void aarch64_sve_change_el(CPUARMState *env, int old_el,

target/arm/gdbstub.c

@@ -32,7 +32,7 @@ typedef struct RegisterSysregXmlParam {
    We hack round this by giving the FPA regs zero size when talking to a
    newer gdb.  */
 
-int arm_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int arm_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     ARMCPU *cpu = ARM_CPU(cs);
     CPUARMState *env = &cpu->env;

target/arm/gdbstub64.c

@@ -20,7 +20,7 @@
 #include "cpu.h"
 #include "exec/gdbstub.h"
 
-int aarch64_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int aarch64_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     ARMCPU *cpu = ARM_CPU(cs);
     CPUARMState *env = &cpu->env;

target/arm/helper.c

@@ -48,30 +48,27 @@ static bool get_phys_addr_lpae(CPUARMState *env, target_ulong address,
 
 static void switch_mode(CPUARMState *env, int mode);
 
-static int vfp_gdb_get_reg(CPUARMState *env, uint8_t *buf, int reg)
+static int vfp_gdb_get_reg(CPUARMState *env, GByteArray *buf, int reg)
 {
     ARMCPU *cpu = env_archcpu(env);
     int nregs = cpu_isar_feature(aa32_simd_r32, cpu) ? 32 : 16;
 
     /* VFP data registers are always little-endian.  */
     if (reg < nregs) {
-        stq_le_p(buf, *aa32_vfp_dreg(env, reg));
-        return 8;
+        return gdb_get_reg64(buf, *aa32_vfp_dreg(env, reg));
     }
     if (arm_feature(env, ARM_FEATURE_NEON)) {
         /* Aliases for Q regs.  */
         nregs += 16;
         if (reg < nregs) {
             uint64_t *q = aa32_vfp_qreg(env, reg - 32);
-            stq_le_p(buf, q[0]);
-            stq_le_p(buf + 8, q[1]);
-            return 16;
+            return gdb_get_reg128(buf, q[0], q[1]);
         }
     }
     switch (reg - nregs) {
-    case 0: stl_p(buf, env->vfp.xregs[ARM_VFP_FPSID]); return 4;
-    case 1: stl_p(buf, vfp_get_fpscr(env)); return 4;
-    case 2: stl_p(buf, env->vfp.xregs[ARM_VFP_FPEXC]); return 4;
+    case 0: return gdb_get_reg32(buf, env->vfp.xregs[ARM_VFP_FPSID]); break;
+    case 1: return gdb_get_reg32(buf, vfp_get_fpscr(env)); break;
+    case 2: return gdb_get_reg32(buf, env->vfp.xregs[ARM_VFP_FPEXC]); break;
     }
     return 0;
 }
@@ -102,7 +99,7 @@ static int vfp_gdb_set_reg(CPUARMState *env, uint8_t *buf, int reg)
     return 0;
 }
 
-static int aarch64_fpu_gdb_get_reg(CPUARMState *env, uint8_t *buf, int reg)
+static int aarch64_fpu_gdb_get_reg(CPUARMState *env, GByteArray *buf, int reg)
 {
     switch (reg) {
     case 0 ... 31:
@@ -205,7 +202,7 @@ static void write_raw_cp_reg(CPUARMState *env, const ARMCPRegInfo *ri,
     }
 }
 
-static int arm_gdb_get_sysreg(CPUARMState *env, uint8_t *buf, int reg)
+static int arm_gdb_get_sysreg(CPUARMState *env, GByteArray *buf, int reg)
 {
     ARMCPU *cpu = env_archcpu(env);
     const ARMCPRegInfo *ri;

target/cris/cpu.h

@@ -195,8 +195,8 @@ void cris_cpu_dump_state(CPUState *cs, FILE *f, int flags);
 
 hwaddr cris_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
 
-int crisv10_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
-int cris_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int crisv10_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
+int cris_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int cris_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 
 /* you can call this signal handler from your SIGBUS and SIGSEGV

target/cris/gdbstub.c

@@ -21,7 +21,7 @@
 #include "cpu.h"
 #include "exec/gdbstub.h"
 
-int crisv10_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int crisv10_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     CRISCPU *cpu = CRIS_CPU(cs);
     CPUCRISState *env = &cpu->env;
@@ -53,7 +53,7 @@ int crisv10_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
     return 0;
 }
 
-int cris_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int cris_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     CRISCPU *cpu = CRIS_CPU(cs);
     CPUCRISState *env = &cpu->env;

target/hppa/cpu.h

@@ -321,7 +321,7 @@ void cpu_hppa_change_prot_id(CPUHPPAState *env);
 
 int cpu_hppa_signal_handler(int host_signum, void *pinfo, void *puc);
 hwaddr hppa_cpu_get_phys_page_debug(CPUState *cs, vaddr addr);
-int hppa_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int hppa_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int hppa_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 void hppa_cpu_do_interrupt(CPUState *cpu);
 bool hppa_cpu_exec_interrupt(CPUState *cpu, int int_req);

target/hppa/gdbstub.c

@@ -21,7 +21,7 @@
 #include "cpu.h"
 #include "exec/gdbstub.h"
 
-int hppa_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int hppa_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     HPPACPU *cpu = HPPA_CPU(cs);
     CPUHPPAState *env = &cpu->env;

target/i386/cpu.h

@@ -1766,7 +1766,7 @@ void x86_cpu_dump_state(CPUState *cs, FILE *f, int flags);
 hwaddr x86_cpu_get_phys_page_attrs_debug(CPUState *cpu, vaddr addr,
                                          MemTxAttrs *attrs);
 
-int x86_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int x86_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int x86_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 
 void x86_cpu_exec_enter(CPUState *cpu);

target/i386/gdbstub.c

@@ -79,7 +79,7 @@ static const int gpr_map32[8] = { 0, 1, 2, 3, 4, 5, 6, 7 };
 #endif
 
 
-int x86_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int x86_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     X86CPU *cpu = X86_CPU(cs);
     CPUX86State *env = &cpu->env;

target/lm32/cpu.h

@@ -202,7 +202,7 @@ void lm32_cpu_do_interrupt(CPUState *cpu);
 bool lm32_cpu_exec_interrupt(CPUState *cs, int int_req);
 void lm32_cpu_dump_state(CPUState *cpu, FILE *f, int flags);
 hwaddr lm32_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
-int lm32_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int lm32_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int lm32_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 
 typedef enum {

target/lm32/gdbstub.c

@@ -22,7 +22,7 @@
 #include "exec/gdbstub.h"
 #include "hw/lm32/lm32_pic.h"
 
-int lm32_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int lm32_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     LM32CPU *cpu = LM32_CPU(cs);
     CPULM32State *env = &cpu->env;

target/m68k/cpu.h

@@ -168,7 +168,7 @@ void m68k_cpu_do_interrupt(CPUState *cpu);
 bool m68k_cpu_exec_interrupt(CPUState *cpu, int int_req);
 void m68k_cpu_dump_state(CPUState *cpu, FILE *f, int flags);
 hwaddr m68k_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
-int m68k_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
+int m68k_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 int m68k_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 
 void m68k_tcg_init(void);

target/m68k/gdbstub.c

@@ -21,7 +21,7 @@
 #include "cpu.h"
 #include "exec/gdbstub.h"
 
-int m68k_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
+int m68k_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
 {
     M68kCPU *cpu = M68K_CPU(cs);
     CPUM68KState *env = &cpu->env;