Add a sysentvec for CloudABI on x86-64.

Summary:
For CloudABI we need to put two things on the stack of new processes:
the argument data (a binary blob; not strings) and a startup data
structure. The startup data structure contains interesting things such
as a pointer to the ELF program header, the thread ID of the initial
thread, a stack smashing protection canary, and a pointer to the
argument data.

Fetching system call arguments and setting the return value is similar
to FreeBSD. The only differences are that system call 0 does not exist
and that we call into cloudabi_convert_errno() to convert the error
code. We also need this function in a couple of other places, so we'd
better reuse it here.

Reviewers: dchagin, kib

Reviewed By: kib

Subscribers: imp

Differential Revision: https://reviews.freebsd.org/D3098

2 files changed, 26 insertions, 23 deletions

diff --git a/sys/contrib/cloudabi/syscalldefs_md.h b/sys/contrib/cloudabi/syscalldefs_md.h
index 95dd129..6fc26f1 100644
--- a/sys/contrib/cloudabi/syscalldefs_md.h
+++ b/sys/contrib/cloudabi/syscalldefs_md.h
@@ -43,6 +43,19 @@
 
 typedef void IDENT(threadentry_t)(cloudabi_tid_t, PTR(void));
 
+// Auxiliary vector entry, used to provide paramters on startup.
+typedef struct {
+  uint32_t a_type;
+  union {
+    MEMBER(IDENT(size_t)) a_val;
+    MEMBER(PTR(void)) a_ptr;
+  };
+} IDENT(auxv_t);
+ASSERT_OFFSET(auxv_t, a_type, 0, 0);
+ASSERT_OFFSET(auxv_t, a_val, 4, 8);
+ASSERT_OFFSET(auxv_t, a_ptr, 4, 8);
+ASSERT_SIZE(auxv_t, 8, 16);
+
 typedef struct {
   MEMBER(PTR(const void)) iov_base;
   MEMBER(IDENT(size_t)) iov_len;
@@ -162,29 +175,6 @@ ASSERT_OFFSET(send_out_t, so_datalen, 0, 0);
 ASSERT_SIZE(send_out_t, 4, 8);
 
 typedef struct {
-  MEMBER(PTR(const void)) sd_arg;   // Program argument data.
-  MEMBER(IDENT(size_t)) sd_arglen;  // Program argument data size.
-
-  MEMBER(PTR(void)) sd_elf_phdr;         // ELF program header.
-  MEMBER(IDENT(size_t)) sd_elf_phdrlen;  // ELF program header length.
-
-  MEMBER(cloudabi_tid_t) sd_thread_id;  // Thread ID.
-  MEMBER(uint64_t) sd_random_seed;      // Random seed, used for SSP.
-
-  MEMBER(uint32_t) sd_ncpus;     // Number of CPUs.
-  MEMBER(uint32_t) sd_pagesize;  // Page size.
-} IDENT(startup_data_t);
-ASSERT_OFFSET(startup_data_t, sd_arg, 0, 0);
-ASSERT_OFFSET(startup_data_t, sd_arglen, 4, 8);
-ASSERT_OFFSET(startup_data_t, sd_elf_phdr, 8, 16);
-ASSERT_OFFSET(startup_data_t, sd_elf_phdrlen, 12, 24);
-ASSERT_OFFSET(startup_data_t, sd_thread_id, 16, 32);
-ASSERT_OFFSET(startup_data_t, sd_random_seed, 24, 40);
-ASSERT_OFFSET(startup_data_t, sd_ncpus, 32, 48);
-ASSERT_OFFSET(startup_data_t, sd_pagesize, 36, 52);
-ASSERT_SIZE(startup_data_t, 40, 56);
-
-typedef struct {
   MEMBER(cloudabi_userdata_t) userdata;
   MEMBER(uint16_t) flags;
   MEMBER(cloudabi_eventtype_t) type;
diff --git a/sys/contrib/cloudabi/syscalldefs_mi.h b/sys/contrib/cloudabi/syscalldefs_mi.h
index 75d79f4..810c0f2 100644
--- a/sys/contrib/cloudabi/syscalldefs_mi.h
+++ b/sys/contrib/cloudabi/syscalldefs_mi.h
@@ -40,6 +40,19 @@
 #define CLOUDABI_ADVICE_SEQUENTIAL 5
 #define CLOUDABI_ADVICE_WILLNEED 6
 
+// Auxiliary vector entries. All entries that are also part of the
+// x86-64 ABI use the same number. All extensions start at 256.
+#define CLOUDABI_AT_ARGDATA 256
+#define CLOUDABI_AT_ARGDATALEN 257
+#define CLOUDABI_AT_CANARY 258
+#define CLOUDABI_AT_CANARYLEN 259
+#define CLOUDABI_AT_NCPUS 260
+#define CLOUDABI_AT_NULL 0
+#define CLOUDABI_AT_PAGESZ 6
+#define CLOUDABI_AT_PHDR 3
+#define CLOUDABI_AT_PHNUM 4
+#define CLOUDABI_AT_TID 261
+
 // Clocks.
 #define CLOUDABI_CLOCK_MONOTONIC 1
 #define CLOUDABI_CLOCK_PROCESS_CPUTIME_ID 2