Subject: [PATCH v3 7/7] Support fully typed symbol access mode
From: Aravinda Prasad <aravinda@linux.vnet.ibm.com>
Date: Fri, 14 Dec 2012 14:57:01 +0530
Message-ID: <20121214092701.4854.47217.stgit@aravinda>
In-Reply-To: <20121214092300.4854.30720.stgit@aravinda>
References: <20121214092300.4854.30720.stgit@aravinda>
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To: kumagai-atsushi@mxc.nes.nec.co.jp, kexec@lists.infradead.org
Cc: LChouinard@s2sys.com, mahesh@linux.vnet.ibm.com, tachibana@mxm.nes.nec.co.jp, ananth@in.ibm.com, buendgen@de.ibm.com

Eppic enables access to symbols in two ways. The first, is a more
natural mode in that it makes symbols available as fully typed
entities. The second, is generic and treats all symbols as an address
to data which then needs to be cast to the proper type explicitly. The
former obviously enables an easier cut & pasting of target code into
eppic code.

Currently generic symbol access mode is supported. This patch extends
the functionality to include support for fully typed symbol access mode
(which will be the default mode) in eppic macros. User can switch to
generic symbol access mode by setting the following environmental
variable - EPPIC_LEGACY_MODE. libeppic.a will take care of handling
EPPIC_LEGACY_MODE. libeppic.a will pass NULL to VALUE_S* argument of
apigetval() call back function if EPPIC_LEGACY_MODE is set.

Refer to http://code.google.com/p/eppic/ for more information.

Signed-off-by: Aravinda Prasad <aravinda@linux.vnet.ibm.com>
---
 dwarf_info.c      |   52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 dwarf_info.h      |    2 ++
 extension_eppic.c |   24 ++++++++++++++++++++++++
 3 files changed, 78 insertions(+), 0 deletions(-)

diff --git a/dwarf_info.c b/dwarf_info.c
index f66d351..22c9e2f 100644
--- a/dwarf_info.c
+++ b/dwarf_info.c
@@ -119,6 +119,15 @@ is_search_domain(int cmd)
 }
 
 static int
+is_search_die(int cmd)
+{
+	if (cmd == DWARF_INFO_GET_DIE)
+		return TRUE;
+	else
+		return FALSE;
+}
+
+static int
 process_module (Dwfl_Module *dwflmod,
 		void **userdata __attribute__ ((unused)),
 		const char *name __attribute__ ((unused)),
@@ -858,6 +867,25 @@ search_domain(Dwarf_Die *die, int *found)
 }
 
 static void
+search_die(Dwarf_Die *die, int *found)
+{
+	const char *name;
+
+	do {
+		name = dwarf_diename(die);
+
+		if ((!name) || strcmp(name, dwarf_info.symbol_name))
+			continue;
+
+		if (found)
+			*found = TRUE;
+
+		dwarf_info.die_offset = dwarf_dieoffset(die);
+		return;
+	} while (!dwarf_siblingof(die, die));
+}
+
+static void
 search_die_tree(Dwarf_Die *die, int *found)
 {
 	Dwarf_Die child;
@@ -885,6 +913,9 @@ search_die_tree(Dwarf_Die *die, int *found)
 
 	else if (is_search_domain(dwarf_info.cmd))
 		search_domain(die, found);
+
+	else if (is_search_die(dwarf_info.cmd))
+		search_die(die, found);
 }
 
 static int
@@ -1452,6 +1483,27 @@ get_die_name(unsigned long long die_off)
 }
 
 /*
+ * Get the die offset given the die name
+ */
+unsigned long long
+get_die_offset(char *sysname)
+{
+	dwarf_info.cmd         = DWARF_INFO_GET_DIE;
+	dwarf_info.symbol_name = sysname;
+	dwarf_info.type_name   = NULL;
+	dwarf_info.struct_size = NOT_FOUND_STRUCTURE;
+	dwarf_info.die_offset  = 0;
+
+	if (!sysname)
+		return 0;
+
+	if (!get_debug_info())
+		return 0;
+
+	return (unsigned long long)dwarf_info.die_offset;
+}
+
+/*
  * Get length attribute given the die offset
  */
 int
diff --git a/dwarf_info.h b/dwarf_info.h
index d1d15a9..c5128f2 100644
--- a/dwarf_info.h
+++ b/dwarf_info.h
@@ -55,6 +55,7 @@ enum {
 	DWARF_INFO_GET_DOMAIN_REF,
 	DWARF_INFO_GET_DOMAIN_STRING,
 	DWARF_INFO_GET_DOMAIN_BASE,
+	DWARF_INFO_GET_DIE,
 };
 
 char *get_dwarf_module_name(void);
@@ -76,6 +77,7 @@ int get_die_member(unsigned long long die_off, int index, long *offset,
 int get_die_attr_type(unsigned long long die_off, int *type_flag,
 	unsigned long long *die_attr_off);
 char *get_die_name(unsigned long long die_off);
+unsigned long long get_die_offset(char *sysname);
 int get_die_length(unsigned long long die_off, int flag);
 int set_dwarf_debuginfo(char *mod_name, char *os_release, char *name_debuginfo, int fd_debuginfo);
 
diff --git a/extension_eppic.c b/extension_eppic.c
index 85dfdcd..835bd2d 100644
--- a/extension_eppic.c
+++ b/extension_eppic.c
@@ -313,6 +313,30 @@ apigetval(char *name, ull *val, VALUE_S *value)
 		return 0;
 
 	*val = ptr;
+
+	if (!value)
+		return 1;
+
+	/* Support for fully typed symbol access */
+	ull type;
+	TYPE_S *stype;
+
+	type = get_die_offset(name);
+	stype = eppic_gettype(value);
+
+	apigetrtype(type, stype);
+
+	eppic_pushref(stype, 1);
+	eppic_setmemaddr(value, *val);
+	eppic_do_deref(1, value, value);
+
+	*val = eppic_getval(value);
+
+	if (!eppic_typeislocal(stype) && eppic_type_getidx(stype) > 100) {
+		char *tname = get_die_name(eppic_type_getidx(stype));
+		if (tname)
+			eppic_chktype(stype, tname);
+	}
 	return 1;
 }
 

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