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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v4 07/34] arm/x86: Use struct virtual_region to do bug, symbol, and (x86) exception tables
lookup.
During execution of the hypervisor we have two regions of
executable code - stext -> _etext, and _sinittext -> _einitext.
The later is not needed after bootup.
We also have various built-in macros and functions to search
in between those two swaths depending on the state of the system.
That is either for bug_frames, exceptions (x86) or symbol
names for the instruction.
With xSplice in the picture - we need a mechansim for new payloads
to searched as well for all of this.
Originally we had extra 'if (xsplice)...' but that gets
a bit tiring and does not hook up nicely.
This 'struct virtual_region' and virtual_region_list provide a
mechanism to search for the bug_frames,exception table,
and symbol names entries without having various calls in
other sub-components in the system.
Code which wishes to participate in bug_frames and exception table
entries search has to only use two public APIs:
- register_virtual_region
- unregister_virtual_region
to let the core code know. Furthermore there are also overrides
via the .skip function. There are three possible flags that
can be passed in - depending on what kind of search is being
done. A return of 1 means skip this region. If the .skip is
NULL the region will be considered.
The ->lookup_symbol will only be used if ->skip returns 1
for CHECKING_SYMBOLS (and of course if it points to
a function). Otherwise the default internal symbol lookup
mechanism is used.
Suggested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
Cc: Julien Grall <julien.grall@xxxxxxx>
Cc: Keir Fraser <keir@xxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
---
xen/arch/arm/traps.c | 45 ++++++++++-----
xen/arch/x86/extable.c | 16 +++++-
xen/arch/x86/setup.c | 3 +-
xen/arch/x86/traps.c | 46 +++++++++------
xen/common/Makefile | 1 +
xen/common/bug_ex_symbols.c | 119 +++++++++++++++++++++++++++++++++++++++
xen/common/symbols.c | 29 +++++++++-
xen/include/xen/bug_ex_symbols.h | 74 ++++++++++++++++++++++++
xen/include/xen/kernel.h | 2 +
xen/include/xen/symbols.h | 9 +++
10 files changed, 307 insertions(+), 37 deletions(-)
create mode 100644 xen/common/bug_ex_symbols.c
create mode 100644 xen/include/xen/bug_ex_symbols.h
diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index 31d2115..b62c91f 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -16,6 +16,7 @@
* GNU General Public License for more details.
*/
+#include <xen/bug_ex_symbols.h>
#include <xen/config.h>
#include <xen/stdbool.h>
#include <xen/init.h>
@@ -101,6 +102,8 @@ integer_param("debug_stack_lines", debug_stack_lines);
void init_traps(void)
{
+ setup_virtual_regions();
+
/* Setup Hyp vector base */
WRITE_SYSREG((vaddr_t)hyp_traps_vector, VBAR_EL2);
@@ -1077,27 +1080,39 @@ void do_unexpected_trap(const char *msg, struct
cpu_user_regs *regs)
int do_bug_frame(struct cpu_user_regs *regs, vaddr_t pc)
{
- const struct bug_frame *bug;
+ const struct bug_frame *bug = NULL;
const char *prefix = "", *filename, *predicate;
unsigned long fixup;
- int id, lineno;
- static const struct bug_frame *const stop_frames[] = {
- __stop_bug_frames_0,
- __stop_bug_frames_1,
- __stop_bug_frames_2,
- NULL
- };
+ int id = -1, lineno;
+ struct virtual_region *region;
- for ( bug = __start_bug_frames, id = 0; stop_frames[id]; ++bug )
+ list_for_each_entry( region, &virtual_region_list, list )
{
- while ( unlikely(bug == stop_frames[id]) )
- ++id;
+ unsigned int i;
- if ( ((vaddr_t)bug_loc(bug)) == pc )
- break;
- }
+ if ( region->skip && region->skip(CHECKING_BUG_FRAME, region->priv) )
+ continue;
+
+ if ( pc < region->start || pc > region->end )
+ continue;
- if ( !stop_frames[id] )
+ for ( id = 0; id < BUGFRAME_NR; id++ )
+ {
+ const struct bug_frame *b = NULL;
+
+ for ( i = 0, b = region->frame[id].bugs;
+ i < region->frame[id].n_bugs; b++, i++ )
+ {
+ if ( ((vaddr_t)bug_loc(b)) == pc )
+ {
+ bug = b;
+ goto found;
+ }
+ }
+ }
+ }
+ found:
+ if ( !bug )
return -ENOENT;
/* WARN, BUG or ASSERT: decode the filename pointer and line number. */
diff --git a/xen/arch/x86/extable.c b/xen/arch/x86/extable.c
index 89b5bcb..6e083a8 100644
--- a/xen/arch/x86/extable.c
+++ b/xen/arch/x86/extable.c
@@ -1,6 +1,8 @@
+#include <xen/bug_ex_symbols.h>
#include <xen/config.h>
#include <xen/init.h>
+#include <xen/list.h>
#include <xen/perfc.h>
#include <xen/sort.h>
#include <xen/spinlock.h>
@@ -80,8 +82,18 @@ search_one_table(const struct exception_table_entry *first,
unsigned long
search_exception_table(unsigned long addr)
{
- return search_one_table(
- __start___ex_table, __stop___ex_table-1, addr);
+ struct virtual_region *region;
+
+ list_for_each_entry( region, &virtual_region_list, list )
+ {
+ if ( region->skip && region->skip(CHECKING_EXCEPTION, region->priv) )
+ continue;
+
+ if ( (addr >= region->start) && (addr < region->end) )
+ return search_one_table(region->ex, region->ex_end-1, addr);
+ }
+
+ return 0;
}
unsigned long
diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index a8bf2c9..115e6fd 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -1,3 +1,4 @@
+#include <xen/bug_ex_symbols.h>
#include <xen/config.h>
#include <xen/init.h>
#include <xen/lib.h>
@@ -614,8 +615,8 @@ void __init noreturn __start_xen(unsigned long mbi_p)
load_system_tables();
smp_prepare_boot_cpu();
- sort_exception_tables();
+ setup_virtual_regions();
/* Full exception support from here on in. */
loader = (mbi->flags & MBI_LOADERNAME)
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 564a107..eeada97 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -24,6 +24,7 @@
* Gareth Hughes <gareth@xxxxxxxxxxx>, May 2000
*/
+#include <xen/bug_ex_symbols.h>
#include <xen/config.h>
#include <xen/init.h>
#include <xen/sched.h>
@@ -1132,18 +1133,12 @@ static int emulate_forced_invalid_op(struct
cpu_user_regs *regs)
void do_invalid_op(struct cpu_user_regs *regs)
{
- const struct bug_frame *bug;
+ const struct bug_frame *bug = NULL;
u8 bug_insn[2];
const char *prefix = "", *filename, *predicate, *eip = (char *)regs->eip;
unsigned long fixup;
- int id, lineno;
- static const struct bug_frame *const stop_frames[] = {
- __stop_bug_frames_0,
- __stop_bug_frames_1,
- __stop_bug_frames_2,
- __stop_bug_frames_3,
- NULL
- };
+ int id = -1, lineno;
+ struct virtual_region *region;
DEBUGGER_trap_entry(TRAP_invalid_op, regs);
@@ -1160,16 +1155,35 @@ void do_invalid_op(struct cpu_user_regs *regs)
memcmp(bug_insn, "\xf\xb", sizeof(bug_insn)) )
goto die;
- for ( bug = __start_bug_frames, id = 0; stop_frames[id]; ++bug )
+ list_for_each_entry( region, &virtual_region_list, list )
{
- while ( unlikely(bug == stop_frames[id]) )
- ++id;
- if ( bug_loc(bug) == eip )
- break;
+ unsigned int i;
+
+ if ( region->skip && region->skip(CHECKING_BUG_FRAME, region->priv) )
+ continue;
+
+ if ( regs->eip < region->start || regs->eip > region->end )
+ continue;
+
+ for ( id = 0; id < BUGFRAME_NR; id++ )
+ {
+ const struct bug_frame *b = NULL;
+
+ for ( i = 0, b = region->frame[id].bugs;
+ i < region->frame[id].n_bugs; b++, i++ )
+ {
+ if ( bug_loc(b) == eip )
+ {
+ bug = b;
+ goto found;
+ }
+ }
+ }
}
- if ( !stop_frames[id] )
- goto die;
+ found:
+ if ( !bug )
+ goto die;
eip += sizeof(bug_insn);
if ( id == BUGFRAME_run_fn )
{
diff --git a/xen/common/Makefile b/xen/common/Makefile
index 82625a5..76d7b07 100644
--- a/xen/common/Makefile
+++ b/xen/common/Makefile
@@ -1,4 +1,5 @@
obj-y += bitmap.o
+obj-y += bug_ex_symbols.o
obj-$(CONFIG_CORE_PARKING) += core_parking.o
obj-y += cpu.o
obj-y += cpupool.o
diff --git a/xen/common/bug_ex_symbols.c b/xen/common/bug_ex_symbols.c
new file mode 100644
index 0000000..77bb72b
--- /dev/null
+++ b/xen/common/bug_ex_symbols.c
@@ -0,0 +1,119 @@
+/*
+ * Copyright (c) 2016 Oracle and/or its affiliates. All rights reserved.
+ *
+ */
+
+#include <xen/bug_ex_symbols.h>
+#include <xen/config.h>
+#include <xen/kernel.h>
+#include <xen/init.h>
+#include <xen/spinlock.h>
+
+extern char __stext[];
+
+struct virtual_region kernel_text = {
+ .list = LIST_HEAD_INIT(kernel_text.list),
+ .start = (unsigned long)_stext,
+ .end = (unsigned long)_etext,
+#ifdef CONFIG_X86
+ .ex = (struct exception_table_entry *)__start___ex_table,
+ .ex_end = (struct exception_table_entry *)__stop___ex_table,
+#endif
+};
+
+/*
+ * The kernel_inittext should only be used when system_state
+ * is booting. Otherwise all accesses should be ignored.
+ */
+static bool_t ignore_if_active(unsigned int flag, unsigned long priv)
+{
+ return (system_state >= SYS_STATE_active);
+}
+
+/*
+ * Becomes irrelevant when __init sections are cleared.
+ */
+struct virtual_region kernel_inittext = {
+ .list = LIST_HEAD_INIT(kernel_inittext.list),
+ .skip = ignore_if_active,
+ .start = (unsigned long)_sinittext,
+ .end = (unsigned long)_einittext,
+#ifdef CONFIG_X86
+ /* Even if they are __init their exception entry still gets stuck here. */
+ .ex = (struct exception_table_entry *)__start___ex_table,
+ .ex_end = (struct exception_table_entry *)__stop___ex_table,
+#endif
+};
+
+/*
+ * No locking. Additions are done either at startup (when there is only
+ * one CPU) or when all CPUs are running without IRQs.
+ *
+ * Deletions are big tricky. We MUST make sure all but one CPU
+ * are running cpu_relax().
+ *
+ */
+LIST_HEAD(virtual_region_list);
+
+int register_virtual_region(struct virtual_region *r)
+{
+ ASSERT(!local_irq_is_enabled());
+
+ list_add_tail(&r->list, &virtual_region_list);
+ return 0;
+}
+
+void unregister_virtual_region(struct virtual_region *r)
+{
+ ASSERT(!local_irq_is_enabled());
+
+ list_del_init(&r->list);
+}
+
+void __init setup_virtual_regions(void)
+{
+ ssize_t sz;
+ unsigned int i, idx;
+ static const struct bug_frame *const stop_frames[] = {
+ __start_bug_frames,
+ __stop_bug_frames_0,
+ __stop_bug_frames_1,
+ __stop_bug_frames_2,
+#ifdef CONFIG_X86
+ __stop_bug_frames_3,
+#endif
+ NULL
+ };
+
+#ifdef CONFIG_X86
+ sort_exception_tables();
+#endif
+
+ /* N.B. idx != i */
+ for ( idx = 0, i = 1; stop_frames[i]; i++, idx++ )
+ {
+ struct bug_frame *s;
+
+ s = (struct bug_frame *)stop_frames[i-1];
+ sz = stop_frames[i] - s;
+
+ kernel_text.frame[idx].n_bugs = sz;
+ kernel_text.frame[idx].bugs = s;
+
+ kernel_inittext.frame[idx].n_bugs = sz;
+ kernel_inittext.frame[idx].bugs = s;
+ }
+
+ register_virtual_region(&kernel_text);
+ register_virtual_region(&kernel_inittext);
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/common/symbols.c b/xen/common/symbols.c
index a59c59d..2cc416e 100644
--- a/xen/common/symbols.c
+++ b/xen/common/symbols.c
@@ -10,6 +10,7 @@
* compression (see tools/symbols.c for a more complete description)
*/
+#include <xen/bug_ex_symbols.h>
#include <xen/config.h>
#include <xen/symbols.h>
#include <xen/kernel.h>
@@ -95,10 +96,28 @@ static unsigned int get_symbol_offset(unsigned long pos)
return name - symbols_names;
}
+bool_t __is_active_kernel_text(unsigned long addr, symbols_lookup_t *cb)
+{
+ struct virtual_region *region;
+
+ list_for_each_entry( region, &virtual_region_list, list )
+ {
+ if ( region->skip && region->skip(CHECKING_SYMBOL, region->priv) )
+ continue;
+
+ if ( addr >= region->start && addr < region->end )
+ {
+ if ( cb && region->symbols_lookup )
+ *cb = region->symbols_lookup;
+ return 1;
+ }
+ }
+ return 0;
+}
+
bool_t is_active_kernel_text(unsigned long addr)
{
- return (is_kernel_text(addr) ||
- (system_state < SYS_STATE_active && is_kernel_inittext(addr)));
+ return __is_active_kernel_text(addr, NULL);
}
const char *symbols_lookup(unsigned long addr,
@@ -108,13 +127,17 @@ const char *symbols_lookup(unsigned long addr,
{
unsigned long i, low, high, mid;
unsigned long symbol_end = 0;
+ symbols_lookup_t symbol_lookup = NULL;
namebuf[KSYM_NAME_LEN] = 0;
namebuf[0] = 0;
- if (!is_active_kernel_text(addr))
+ if (!__is_active_kernel_text(addr, &symbol_lookup))
return NULL;
+ if (symbol_lookup)
+ return (symbol_lookup)(addr, symbolsize, offset, namebuf);
+
/* do a binary search on the sorted symbols_addresses array */
low = 0;
high = symbols_num_syms;
diff --git a/xen/include/xen/bug_ex_symbols.h b/xen/include/xen/bug_ex_symbols.h
new file mode 100644
index 0000000..6f3401b
--- /dev/null
+++ b/xen/include/xen/bug_ex_symbols.h
@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2016 Oracle and/or its affiliates. All rights reserved.
+ *
+ */
+
+#ifndef __BUG_EX_SYMBOL_LIST__
+#define __BUG_EX_SYMBOL_LIST__
+
+#include <xen/config.h>
+#include <xen/list.h>
+#include <xen/symbols.h>
+
+#ifdef CONFIG_X86
+#include <asm/uaccess.h>
+#endif
+#include <asm/bug.h>
+
+struct virtual_region
+{
+ struct list_head list;
+
+#define CHECKING_SYMBOL (1<<1)
+#define CHECKING_BUG_FRAME (1<<2)
+#define CHECKING_EXCEPTION (1<<3)
+ /*
+ * Whether to skip this region for particular searches. The flag
+ * can be CHECKING_[SYMBOL|BUG_FRAMES|EXCEPTION].
+ *
+ * If the function returns 1 this region will be skipped.
+ */
+ bool_t (*skip)(unsigned int flag, unsigned long priv);
+
+ unsigned long start; /* Virtual address start. */
+ unsigned long end; /* Virtual address start. */
+
+ /*
+ * If ->skip returns false for CHECKING_SYMBOL we will use
+ * 'symbols_lookup' callback to retrieve the name of the
+ * addr between start and end. If this is NULL the
+ * default lookup mechanism is used (the skip value is
+ * ignored).
+ */
+ symbols_lookup_t symbols_lookup;
+
+ struct {
+ struct bug_frame *bugs; /* The pointer to array of bug frames. */
+ ssize_t n_bugs; /* The number of them. */
+ } frame[BUGFRAME_NR];
+
+#ifdef CONFIG_X86
+ struct exception_table_entry *ex;
+ struct exception_table_entry *ex_end;
+#endif
+
+ unsigned long priv; /* To be used by above funcionts if need to. */
+};
+
+extern struct list_head virtual_region_list;
+
+extern void setup_virtual_regions(void);
+extern int register_virtual_region(struct virtual_region *r);
+extern void unregister_virtual_region(struct virtual_region *r);
+
+#endif /* __BUG_EX_SYMBOL_LIST__ */
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/include/xen/kernel.h b/xen/include/xen/kernel.h
index 548b64d..8cf7af7 100644
--- a/xen/include/xen/kernel.h
+++ b/xen/include/xen/kernel.h
@@ -65,12 +65,14 @@
1; \
})
+
extern char _start[], _end[], start[];
#define is_kernel(p) ({ \
char *__p = (char *)(unsigned long)(p); \
(__p >= _start) && (__p < _end); \
})
+/* For symbols_lookup usage. */
extern char _stext[], _etext[];
#define is_kernel_text(p) ({ \
char *__p = (char *)(unsigned long)(p); \
diff --git a/xen/include/xen/symbols.h b/xen/include/xen/symbols.h
index 1fa0537..fe9ed8f 100644
--- a/xen/include/xen/symbols.h
+++ b/xen/include/xen/symbols.h
@@ -5,6 +5,15 @@
#define KSYM_NAME_LEN 127
+/*
+ * Typedef for the callback functions that symbols_lookup
+ * can call if virtual_region_list has an callback for it.
+ */
+typedef const char *(*symbols_lookup_t)(unsigned long addr,
+ unsigned long *symbolsize,
+ unsigned long *offset,
+ char *namebuf);
+
/* Lookup an address. */
const char *symbols_lookup(unsigned long addr,
unsigned long *symbolsize,
--
2.5.0
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