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Date:      Thu, 21 Dec 2017 09:21:40 +0000 (UTC)
From:      Ed Schouten <ed@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r327057 - head/usr.bin/truss
Message-ID:  <201712210921.vBL9Leuu046739@repo.freebsd.org>
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Author: ed
Date: Thu Dec 21 09:21:40 2017
New Revision: 327057
URL: https://svnweb.freebsd.org/changeset/base/327057

Log:
  Make truss work for CloudABI executables on i386.
  
  The system call convention is different from i386 binaries running on
  FreeBSD/amd64, but this is not noticeable by executables. On
  FreeBSD/amd64, the vDSO already does padding of arguments and return
  values to 64-bit values. On i386, it does not, meaning that system call
  return values are simply stored in registers.

Added:
  head/usr.bin/truss/i386-cloudabi32.c
     - copied, changed from r327055, head/usr.bin/truss/amd64-cloudabi32.c
Modified:
  head/usr.bin/truss/Makefile

Modified: head/usr.bin/truss/Makefile
==============================================================================
--- head/usr.bin/truss/Makefile	Thu Dec 21 09:17:48 2017	(r327056)
+++ head/usr.bin/truss/Makefile	Thu Dec 21 09:21:40 2017	(r327057)
@@ -18,6 +18,7 @@ ABIS+=		cloudabi64
 .endif
 .if ${MACHINE_CPUARCH} == "i386"
 ABIS+=		i386-linux
+ABIS+=		cloudabi32
 .endif
 .if ${MACHINE_CPUARCH} == "amd64"
 ABIS+=		amd64-linux

Copied and modified: head/usr.bin/truss/i386-cloudabi32.c (from r327055, head/usr.bin/truss/amd64-cloudabi32.c)
==============================================================================
--- head/usr.bin/truss/amd64-cloudabi32.c	Thu Dec 21 04:23:00 2017	(r327055, copy source)
+++ head/usr.bin/truss/i386-cloudabi32.c	Thu Dec 21 09:21:40 2017	(r327057)
@@ -38,7 +38,7 @@ __FBSDID("$FreeBSD$");
 #include "truss.h"
 
 static int
-amd64_cloudabi32_fetch_args(struct trussinfo *trussinfo, unsigned int narg)
+i386_cloudabi32_fetch_args(struct trussinfo *trussinfo, unsigned int narg)
 {
 	struct current_syscall *cs;
 	struct ptrace_io_desc iorequest;
@@ -46,7 +46,7 @@ amd64_cloudabi32_fetch_args(struct trussinfo *trussinf
 	lwpid_t tid;
 
 	if (narg > 0) {
-		/* Fetch registers, containing the address of the arguments. */
+		/* Fetch registers, containing the stack pointer. */
 		tid = trussinfo->curthread->tid;
 		if (ptrace(PT_GETREGS, tid, (caddr_t)&regs, 0) == -1) {
 			fprintf(trussinfo->outfile,
@@ -54,10 +54,10 @@ amd64_cloudabi32_fetch_args(struct trussinfo *trussinf
 			return (-1);
 		}
 
-		/* Fetch arguments. They are already padded to 64 bits. */
+		/* Fetch arguments. */
 		cs = &trussinfo->curthread->cs;
 		iorequest.piod_op = PIOD_READ_D;
-		iorequest.piod_offs = (void *)regs.r_rcx;
+		iorequest.piod_offs = (void **)regs.r_esp + 1;
 		iorequest.piod_addr = cs->args;
 		iorequest.piod_len = sizeof(cs->args[0]) * narg;
 		if (ptrace(PT_IO, tid, (caddr_t)&iorequest, 0) == -1 ||
@@ -68,45 +68,31 @@ amd64_cloudabi32_fetch_args(struct trussinfo *trussinf
 }
 
 static int
-amd64_cloudabi32_fetch_retval(struct trussinfo *trussinfo, long *retval,
+i386_cloudabi32_fetch_retval(struct trussinfo *trussinfo, long *retval,
     int *errorp)
 {
-	struct ptrace_io_desc iorequest;
 	struct reg regs;
 	lwpid_t tid;
 
-	/* Fetch registers, containing the address of the return values. */
 	tid = trussinfo->curthread->tid;
 	if (ptrace(PT_GETREGS, tid, (caddr_t)&regs, 0) == -1) {
 		fprintf(trussinfo->outfile, "-- CANNOT READ REGISTERS --\n");
 		return (-1);
 	}
 
-	if (regs.r_rax == 0) {
-		/* System call succeeded. Fetch return values. */
-		iorequest.piod_op = PIOD_READ_D;
-		iorequest.piod_offs = (void *)regs.r_rcx;
-		iorequest.piod_addr = retval;
-		iorequest.piod_len = sizeof(retval[0]) * 2;
-		if (ptrace(PT_IO, tid, (caddr_t)&iorequest, 0) == -1 ||
-		    iorequest.piod_len == 0)
-			return (-1);
-		*errorp = 0;
-	} else {
-		/* System call failed. Set error. */
-		retval[0] = regs.r_rax;
-		*errorp = 1;
-	}
+	retval[0] = regs.r_eax;
+	retval[1] = regs.r_edx;
+	*errorp = (regs.r_eflags & PSL_C) != 0;
 	return (0);
 }
 
-static struct procabi amd64_cloudabi32 = {
+static struct procabi i386_cloudabi32 = {
 	"CloudABI ELF32",
 	SYSDECODE_ABI_CLOUDABI32,
-	amd64_cloudabi32_fetch_args,
-	amd64_cloudabi32_fetch_retval,
-	STAILQ_HEAD_INITIALIZER(amd64_cloudabi32.extra_syscalls),
+	i386_cloudabi32_fetch_args,
+	i386_cloudabi32_fetch_retval,
+	STAILQ_HEAD_INITIALIZER(i386_cloudabi32.extra_syscalls),
 	{ NULL }
 };
 
-PROCABI(amd64_cloudabi32);
+PROCABI(i386_cloudabi32);

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