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authorNamhyung Kim <namhyung@gmail.com>2011-03-24 11:42:29 +0900
committerIngo Molnar <mingo@elte.hu>2011-03-24 08:36:10 +0100
commit0f77a8d378254f27df4a114a5da67223af1fe93f (patch)
treeedc37c211adce744100d4776e4a28fb868c8b3c0 /lib/vsprintf.c
parentdec2960827c85253d76938dbfa909df3be34958b (diff)
downloadlinux-stericsson-0f77a8d378254f27df4a114a5da67223af1fe93f.tar.gz
vsprintf: Introduce %pB format specifier
The %pB format specifier is for stack backtrace. Its handler sprint_backtrace() does symbol lookup using (address-1) to ensure the address will not point outside of the function. If there is a tail-call to the function marked "noreturn", gcc optimized out the code after the call then causes saved return address points outside of the function (i.e. the start of the next function), so pollutes call trace somewhat. This patch adds the %pB printk mechanism that allows architecture call-trace printout functions to improve backtrace printouts. Signed-off-by: Namhyung Kim <namhyung@gmail.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: linux-arch@vger.kernel.org LKML-Reference: <1300934550-21394-1-git-send-email-namhyung@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'lib/vsprintf.c')
-rw-r--r--lib/vsprintf.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index d3023df8477f..d9e01fc3168e 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -574,7 +574,9 @@ char *symbol_string(char *buf, char *end, void *ptr,
unsigned long value = (unsigned long) ptr;
#ifdef CONFIG_KALLSYMS
char sym[KSYM_SYMBOL_LEN];
- if (ext != 'f' && ext != 's')
+ if (ext == 'B')
+ sprint_backtrace(sym, value);
+ else if (ext != 'f' && ext != 's')
sprint_symbol(sym, value);
else
kallsyms_lookup(value, NULL, NULL, NULL, sym);
@@ -949,6 +951,7 @@ int kptr_restrict = 1;
* - 'f' For simple symbolic function names without offset
* - 'S' For symbolic direct pointers with offset
* - 's' For symbolic direct pointers without offset
+ * - 'B' For backtraced symbolic direct pointers with offset
* - 'R' For decoded struct resource, e.g., [mem 0x0-0x1f 64bit pref]
* - 'r' For raw struct resource, e.g., [mem 0x0-0x1f flags 0x201]
* - 'M' For a 6-byte MAC address, it prints the address in the
@@ -1008,6 +1011,7 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
/* Fallthrough */
case 'S':
case 's':
+ case 'B':
return symbol_string(buf, end, ptr, spec, *fmt);
case 'R':
case 'r':
@@ -1279,6 +1283,7 @@ qualifier:
* %ps output the name of a text symbol without offset
* %pF output the name of a function pointer with its offset
* %pf output the name of a function pointer without its offset
+ * %pB output the name of a backtrace symbol with its offset
* %pR output the address range in a struct resource with decoded flags
* %pr output the address range in a struct resource with raw flags
* %pM output a 6-byte MAC address with colons