semihosting: Initialize heap once per process

While semihosting isn't really thread aware, the current
implementation allocates space for the heap per-thread.

Remove the heap_base and heap_limit fields from TaskState.
Replace with static variables within do_common_semihosting.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

linux-user/aarch64/cpu_loop.c

@@ -140,9 +140,6 @@ void cpu_loop(CPUARMState *env)
 void target_cpu_copy_regs(CPUArchState *env, target_pt_regs *regs)
 {
     ARMCPU *cpu = env_archcpu(env);
-    CPUState *cs = env_cpu(env);
-    TaskState *ts = get_task_state(cs);
-    struct image_info *info = ts->info;
     int i;
 
     if (!(arm_feature(env, ARM_FEATURE_AARCH64))) {
@@ -167,8 +164,4 @@ void target_cpu_copy_regs(CPUArchState *env, target_pt_regs *regs)
     if (cpu_isar_feature(aa64_pauth, cpu)) {
         qemu_guest_getrandom_nofail(&env->keys, sizeof(env->keys));
     }
-
-    ts->heap_base = info->brk;
-    /* This will be filled in on the first SYS_HEAPINFO call.  */
-    ts->heap_limit = 0;
 }

linux-user/arm/cpu_loop.c

@@ -492,19 +492,16 @@ void target_cpu_copy_regs(CPUArchState *env, target_pt_regs *regs)
     for(i = 0; i < 16; i++) {
         env->regs[i] = regs->uregs[i];
     }
-#if TARGET_BIG_ENDIAN
-    /* Enable BE8.  */
-    if (EF_ARM_EABI_VERSION(info->elf_flags) >= EF_ARM_EABI_VER4
-        && (info->elf_flags & EF_ARM_BE8)) {
-        env->uncached_cpsr |= CPSR_E;
-        env->cp15.sctlr_el[1] |= SCTLR_E0E;
-    } else {
-        env->cp15.sctlr_el[1] |= SCTLR_B;
-    }
-    arm_rebuild_hflags(env);
-#endif
 
-    ts->heap_base = info->brk;
-    /* This will be filled in on the first SYS_HEAPINFO call.  */
-    ts->heap_limit = 0;
+    if (TARGET_BIG_ENDIAN) {
+        /* Enable BE8.  */
+        if (EF_ARM_EABI_VERSION(info->elf_flags) >= EF_ARM_EABI_VER4
+            && (info->elf_flags & EF_ARM_BE8)) {
+            env->uncached_cpsr |= CPSR_E;
+            env->cp15.sctlr_el[1] |= SCTLR_E0E;
+        } else {
+            env->cp15.sctlr_el[1] |= SCTLR_B;
+        }
+        arm_rebuild_hflags(env);
+    }
 }

linux-user/m68k/cpu_loop.c

@@ -94,10 +94,6 @@ void cpu_loop(CPUM68KState *env)
 
 void target_cpu_copy_regs(CPUArchState *env, target_pt_regs *regs)
 {
-    CPUState *cpu = env_cpu(env);
-    TaskState *ts = get_task_state(cpu);
-    struct image_info *info = ts->info;
-
     env->pc = regs->pc;
     env->dregs[0] = regs->d0;
     env->dregs[1] = regs->d1;
@@ -116,8 +112,4 @@ void target_cpu_copy_regs(CPUArchState *env, target_pt_regs *regs)
     env->aregs[6] = regs->a6;
     env->aregs[7] = regs->usp;
     env->sr = regs->sr;
-
-    ts->heap_base = info->brk;
-    /* This will be filled in on the first SYS_HEAPINFO call.  */
-    ts->heap_limit = 0;
 }

linux-user/qemu.h

@@ -121,11 +121,6 @@ struct TaskState {
     abi_ulong child_tidptr;
 #ifdef TARGET_M68K
     abi_ulong tp_value;
-#endif
-#if defined(TARGET_ARM) || defined(TARGET_M68K) || defined(TARGET_RISCV)
-    /* Extra fields for semihosted binaries.  */
-    abi_ulong heap_base;
-    abi_ulong heap_limit;
 #endif
     int used; /* non zero if used */
     struct image_info *info;

linux-user/riscv/cpu_loop.c

@@ -108,8 +108,4 @@ void target_cpu_copy_regs(CPUArchState *env, target_pt_regs *regs)
         error_report("Incompatible ELF: RVE cpu requires RVE ABI binary");
         exit(EXIT_FAILURE);
     }
-
-    ts->heap_base = info->brk;
-    /* This will be filled in on the first SYS_HEAPINFO call.  */
-    ts->heap_limit = 0;
 }

semihosting/arm-compat-semi.c

@@ -666,7 +666,7 @@ void do_common_semihosting(CPUState *cs)
             int i;
 #ifdef CONFIG_USER_ONLY
             TaskState *ts = get_task_state(cs);
-            target_ulong limit;
+            static abi_ulong heapbase, heaplimit;
 #else
             LayoutInfo info = common_semi_find_bases(cs);
 #endif
@@ -678,24 +678,20 @@ void do_common_semihosting(CPUState *cs)
              * Some C libraries assume the heap immediately follows .bss, so
              * allocate it using sbrk.
              */
-            if (!ts->heap_limit) {
-                abi_ulong ret;
-
-                ts->heap_base = do_brk(0);
-                limit = ts->heap_base + COMMON_SEMI_HEAP_SIZE;
+            if (!heaplimit) {
+                heapbase = do_brk(0);
                 /* Try a big heap, and reduce the size if that fails.  */
-                for (;;) {
-                    ret = do_brk(limit);
+                for (abi_ulong size = COMMON_SEMI_HEAP_SIZE; ; size >>= 1) {
+                    abi_ulong limit = heapbase + size;
+                    abi_ulong ret = do_brk(limit);
                     if (ret >= limit) {
+                        heaplimit = limit;
                         break;
                     }
-                    limit = (ts->heap_base >> 1) + (limit >> 1);
                 }
-                ts->heap_limit = limit;
             }
-
-            retvals[0] = ts->heap_base;
-            retvals[1] = ts->heap_limit;
+            retvals[0] = heapbase;
+            retvals[1] = heaplimit;
             /*
              * Note that semihosting is *not* thread aware.
              * Always return the stack base of the main thread.