[components][lwp] fix signal ordering and ELF segment protection

components/lwp/arch/risc-v/rv64/lwp_gcc.S

@@ -109,6 +109,8 @@ arch_ret_to_user_impl:
     // TODO: we don't support kernel gdb server in risc-v yet
     // so we don't check debug state here and handle debugging bussiness
 
+    /* Signal handling takes sleeping locks and must remain schedulable. */
+    OPEN_INTERRUPT
     call lwp_check_exit_request
     beqz a0, 1f
     mv a0, x0
@@ -121,6 +123,7 @@ arch_ret_to_user_impl:
     call lwp_thread_signal_catch
 
 ret_to_user_exit:
+    CLOSE_INTERRUPT
     RESTORE_ALL
     // `RESTORE_ALL` also reset sp to user sp, and setup sscratch
     sret
@@ -130,8 +133,10 @@ ret_to_user_exit:
  * And handle pending signals;
  */
 arch_signal_quit:
+    OPEN_INTERRUPT
     LOAD a0, FRAME_OFF_SP(sp)
     call arch_signal_ucontext_restore
+    CLOSE_INTERRUPT
 
     /* reset kernel sp to the stack */
     addi sp, sp, CTX_REG_NR * REGBYTES
@@ -167,6 +172,7 @@ arch_thread_signal_enter:
     LOAD t0, FRAME_OFF_SP(a2)
     mv a3, t0
     call arch_signal_ucontext_save
+    CLOSE_INTERRUPT
 
     /** restore kernel sp */
     addi sp, s3, CTX_REG_NR * REGBYTES

components/lwp/lwp_elf.c

@@ -599,6 +599,31 @@ static int elf_zero_bss(struct rt_lwp *lwp, int fd, const Elf_Phdr *phdr, rt_uba
     return RT_EOK;
 }
 
+/**
+ * @brief Derive the memory protection flags from an ELF segment's p_flags.
+ *
+ * @param p_flags ELF program header flags (PF_R, PF_W, PF_X).
+ *
+ * @return Protection flags suitable for elf_map().
+ */
+static size_t elf_prot_from_pflags(uint32_t p_flags)
+{
+    size_t prot = PROT_NONE;
+    if (p_flags & PF_R)
+    {
+        prot |= PROT_READ;
+    }
+    if (p_flags & PF_W)
+    {
+        prot |= PROT_WRITE;
+    }
+    if (p_flags & PF_X)
+    {
+        prot |= PROT_EXEC;
+    }
+    return prot;
+}
+
 /**
  * @brief Map ELF segments into memory.
  *
@@ -626,7 +651,6 @@ static int elf_file_mmap(elf_load_info_t *load_info, elf_info_t *elf_info, rt_ub
     const Elf_Phdr *tmp_phdr = phdr;  /* Current program header */
     int fd = elf_info->fd; /* File descriptor for ELF file */
     rt_ubase_t load_addr;  /* Calculated load address */
-    size_t prot = PROT_READ | PROT_WRITE; /* Memory protection flags */
     size_t flags = MAP_FIXED | MAP_PRIVATE; /* Memory mapping flags */
 
     /* Iterate through all program headers */
@@ -659,8 +683,13 @@ static int elf_file_mmap(elf_load_info_t *load_info, elf_info_t *elf_info, rt_ub
             flags &= ~MAP_FIXED;
         }
 
-        /* Map the segment into memory */
-        map_va = elf_map(load_info->lwp, tmp_phdr, fd, load_addr, prot, flags, map_size);
+        /*
+         * Map the segment with the permissions described by p_flags. When
+         * LWP_USING_MPROTECT is disabled, lwp_user_mm_attr_to_kernel() ignores
+         * the protection and always maps the segment as MMU_MAP_U_RWCB, so
+         * this behaves exactly as before until MPROTECT is enabled.
+         */
+        map_va = elf_map(load_info->lwp, tmp_phdr, fd, load_addr, elf_prot_from_pflags(tmp_phdr->p_flags), flags, map_size);
         if (!map_va)
         {
             LOG_E("%s : elf_map failed", __func__);

components/lwp/lwp_signal.c

@@ -255,9 +255,10 @@ static void sigqueue_enqueue(lwp_sigqueue_t sigqueue, lwp_siginfo_t siginfo)
     rt_bool_t inserted = RT_FALSE;
     rt_list_for_each_entry(idx, &sigqueue->siginfo_list, node)
     {
-        if (idx->ksiginfo.signo >= siginfo->ksiginfo.signo)
+        /* Keep ascending signal order and FIFO order for equal signals. */
+        if (idx->ksiginfo.signo > siginfo->ksiginfo.signo)
         {
-            rt_list_insert_after(&idx->node, &siginfo->node);
+            rt_list_insert_before(&idx->node, &siginfo->node);
             inserted = RT_TRUE;
             break;
         }