From: "Steven Rostedt (Red Hat)" <[email protected]> The SyS_foo() alias wrapper was added to make sure that system call arguments were signed extended. The call itself is to never be used by anything, only the sys_foo() version is. But this symbol is stored in /proc/kallsyms, and is returned sometimes as the name of system call functions when a ksym lookup is made, it confuses the function tracer interface (see available_filter_functions in the tracefs directory).
Al Viro even suggested that this should be removed from kallsyms as well: Link: http://lkml.kernel.org/r/[email protected] Modify the compile time kallsyms.c to check if the function name begins with SyS_ and is before or after the same name that starts with sys_ and if so, do not record it. This saves some space and more importantly removes the confusing variations of the system call name. wc kallsyms.* 90151 284644 3819255 kallsyms.orig 89826 283669 3808628 kallsyms.patched size vmlinux* text data bss dec hex filename 9990933 2368592 1249280 13608805 cfa765 vmlinux.orig 9986837 2368592 1249280 13604709 cf9765 vmlinux.patched This patch only removes SyS_*, it does not do anything with compat_SyS_*. Cc: Al Viro <[email protected]> Signed-off-by: Steven Rostedt <[email protected]> --- scripts/kallsyms.c | 43 ++++++++++++++++++++++++++++++++++++++----- 1 file changed, 38 insertions(+), 5 deletions(-) diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c index 8fa81e84e295..a64d89c6641c 100644 --- a/scripts/kallsyms.c +++ b/scripts/kallsyms.c @@ -193,8 +193,22 @@ static int symbol_in_range(struct sym_entry *s, struct addr_range *ranges, return 0; } -static int symbol_valid(struct sym_entry *s) +static const char *skip_prefix(const char *sym) { + if (symbol_prefix_char && *sym == symbol_prefix_char) + return sym + 1; + return sym; +} + +static int match_sys(const char *sym, const char *sys) +{ + return !strncmp(sys, "sys_", 4) && !strcmp(sym + 4, sys + 4); +} + +static int symbol_valid(int idx) +{ + struct sym_entry *s = &table[idx]; + /* Symbols which vary between passes. Passes 1 and 2 must have * identical symbol lists. The kallsyms_* symbols below are only added * after pass 1, they would be included in pass 2 when --all-symbols is @@ -224,9 +238,7 @@ static int symbol_valid(struct sym_entry *s) if (s->addr < kernel_start_addr) return 0; - /* skip prefix char */ - if (symbol_prefix_char && *sym_name == symbol_prefix_char) - sym_name++; + sym_name = skip_prefix(sym_name); /* if --all-symbols is not specified, then symbols outside the text @@ -255,6 +267,27 @@ static int symbol_valid(struct sym_entry *s) if (strcmp(sym_name, special_symbols[i]) == 0) return 0; + /* Ignore SyS_* alias system calls */ + if (!strncmp(sym_name, "SyS_", 4)) { + char *sym_name_before = ""; + char *sym_name_after = ""; + + if (i > 0) { + sym_name_before = (char *)table[idx-1].sym + 1; + sym_name_before = skip_prefix(sym_name_before); + } + + if (i < table_cnt - 1) { + sym_name_after = (char *)table[idx+1].sym + 1; + sym_name_after = skip_prefix(sym_name_after); + } + + /* If SyS_foo matches a sys_foo, skip it */ + if (match_sys(sym_name, sym_name_before) || + match_sys(sym_name, sym_name_after)) + return 0; + } + for (i = 0; special_suffixes[i]; i++) { int l = strlen(sym_name) - strlen(special_suffixes[i]); @@ -447,7 +480,7 @@ static void build_initial_tok_table(void) pos = 0; for (i = 0; i < table_cnt; i++) { - if ( symbol_valid(&table[i]) ) { + if ( symbol_valid(i) ) { if (pos != i) table[pos] = table[i]; learn_symbol(table[pos].sym, table[pos].len); -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
