[RFC PATCH] kernel/kallsyms.c: only show legal kernel symbol
From: Rusty Russell <hidden>
Date: 2013-10-28 05:50:57
Also in:
lkml
Ming Lei [off-list ref] writes:
On Mon, 28 Oct 2013 13:44:30 +1030 Rusty Russell [off-list ref] wrote:quoted
Ming Lei [off-list ref] writes: I don't know... It would be your job, as the person making the change, to find all the users of kallsyms and prove that. This is why it is easier not to include incorrect values in the kernel's kallsyms in the first place.OK, thanks for your comment, and I figured out one way to do it in scripts/kallsyms.c, could you comment on below patch?
Looks great! Seems like we spent more time arguing than it took you to code that up. Acked-by: Rusty Russell <redacted> Russell, this seems logical for you to take along with the changes which caused the problem? Thanks, Rusty.
quoted hunk ↗ jump to hunk
-- From 4327534dedfa60d208ac3e23db7556c243e1c7dc Mon Sep 17 00:00:00 2001 From: Ming Lei <tom.leiming@gmail.com> Date: Mon, 28 Oct 2013 13:04:49 +0800 Subject: [PATCH] scripts/kallsyms: filter symbols not in kernel address space This patch uses CONFIG_PAGE_OFFSET to filter symbols which are not in kernel address space because these symbols are generally for generating code purpose and can't be run at kernel mode, so we needn't keep them in /proc/kallsyms. For example, on ARM there are some symbols which may be linked in relocatable code section, then perf can't parse symbols any more from /proc/kallsyms, this patch fixes the problem. Cc: Russell King <redacted> Cc: linux-arm-kernel at lists.infradead.org Cc: Rusty Russell <redacted> Cc: Michal Marek <redacted> Signed-off-by: Ming Lei <tom.leiming@gmail.com> --- scripts/kallsyms.c | 12 +++++++++++- scripts/link-vmlinux.sh | 2 ++ 2 files changed, 13 insertions(+), 1 deletion(-)diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c index 487ac6f..9a11f9f 100644 --- a/scripts/kallsyms.c +++ b/scripts/kallsyms.c@@ -55,6 +55,7 @@ static struct sym_entry *table; static unsigned int table_size, table_cnt; static int all_symbols = 0; static char symbol_prefix_char = '\0'; +static unsigned long long kernel_start_addr = 0; int token_profit[0x10000];@@ -65,7 +66,10 @@ unsigned char best_table_len[256]; static void usage(void) { - fprintf(stderr, "Usage: kallsyms [--all-symbols] [--symbol-prefix=<prefix char>] < in.map > out.S\n"); + fprintf(stderr, "Usage: kallsyms [--all-symbols] " + "[--symbol-prefix=<prefix char>] " + "[--page-offset=<CONFIG_PAGE_OFFSET>] " + "< in.map > out.S\n"); exit(1); }@@ -194,6 +198,9 @@ static int symbol_valid(struct sym_entry *s) int i; int offset = 1; + if (s->addr < kernel_start_addr) + return 0; + /* skip prefix char */ if (symbol_prefix_char && *(s->sym + 1) == symbol_prefix_char) offset++;@@ -646,6 +653,9 @@ int main(int argc, char **argv) if ((*p == '"' && *(p+2) == '"') || (*p == '\'' && *(p+2) == '\'')) p++; symbol_prefix_char = *p; + } else if (strncmp(argv[i], "--page-offset=", 14) == 0) { + const char *p = &argv[i][14]; + kernel_start_addr = strtoull(p, NULL, 16); } else usage(); }diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index 0149949..32b10f5 100644 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh@@ -82,6 +82,8 @@ kallsyms() kallsymopt="${kallsymopt} --all-symbols" fi + kallsymopt="${kallsymopt} --page-offset=$CONFIG_PAGE_OFFSET" + local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \ ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}"-- 1.7.9.5 Thanks, -- Ming Lei