The patch titled
Subject: kallsyms: add support for relative offsets in kallsyms address table
has been added to the -mm tree. Its filename is
kallsyms-add-support-for-relative-offsets-in-kallsyms-address-table-v5.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kallsyms-add-support-for-relative-offsets-in-kallsyms-address-table-v5.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kallsyms-add-support-for-relative-offsets-in-kallsyms-address-table-v5.patch
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------------------------------------------------------
From: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Subject: kallsyms: add support for relative offsets in kallsyms address table
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Michal Marek <mmarek@xxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Sudip Mukherjee <sudipm.mukherjee@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
init/Kconfig | 10 +++++----
kernel/kallsyms.c | 8 +++++--
scripts/kallsyms.c | 47 +++++++++++++++++--------------------------
3 files changed, 31 insertions(+), 34 deletions(-)
diff -puN init/Kconfig~kallsyms-add-support-for-relative-offsets-in-kallsyms-address-table-v5 init/Kconfig
--- a/init/Kconfig~kallsyms-add-support-for-relative-offsets-in-kallsyms-address-table-v5
+++ a/init/Kconfig
@@ -1449,13 +1449,15 @@ config KALLSYMS_ABSOLUTE_PERCPU
config KALLSYMS_BASE_RELATIVE
bool
depends on KALLSYMS
- default !IA64
+ default !IA64 && !(TILE && 64BIT)
help
Instead of emitting them as absolute values in the native word size,
emit the symbol references in the kallsyms table as 32-bit entries,
- each containing either an absolute value in the range [0, S32_MAX] or
- a relative value in the range [base, base + S32_MAX], where base is
- the lowest relative symbol address encountered in the image.
+ each containing a relative value in the range [base, base + U32_MAX]
+ or, when KALLSYMS_ABSOLUTE_PERCPU is in effect, each containing either
+ an absolute value in the range [0, S32_MAX] or a relative value in the
+ range [base, base + S32_MAX], where base is the lowest relative symbol
+ address encountered in the image.
On 64-bit builds, this reduces the size of the address table by 50%,
but more importantly, it results in entries whose values are build
diff -puN kernel/kallsyms.c~kallsyms-add-support-for-relative-offsets-in-kallsyms-address-table-v5 kernel/kallsyms.c
--- a/kernel/kallsyms.c~kallsyms-add-support-for-relative-offsets-in-kallsyms-address-table-v5
+++ a/kernel/kallsyms.c
@@ -185,11 +185,15 @@ static unsigned long kallsyms_sym_addres
if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
return kallsyms_addresses[idx];
- /* positive offsets are absolute values */
+ /* values are unsigned offsets if --absolute-percpu is not in effect */
+ if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU))
+ return kallsyms_relative_base + (u32)kallsyms_offsets[idx];
+
+ /* ...otherwise, positive offsets are absolute values */
if (kallsyms_offsets[idx] >= 0)
return kallsyms_offsets[idx];
- /* negative offsets are relative to kallsyms_relative_base - 1 */
+ /* ...and negative offsets are relative to kallsyms_relative_base - 1 */
return kallsyms_relative_base - 1 - kallsyms_offsets[idx];
}
diff -puN scripts/kallsyms.c~kallsyms-add-support-for-relative-offsets-in-kallsyms-address-table-v5 scripts/kallsyms.c
--- a/scripts/kallsyms.c~kallsyms-add-support-for-relative-offsets-in-kallsyms-address-table-v5
+++ a/scripts/kallsyms.c
@@ -375,23 +375,24 @@ static void write_src(void)
for (i = 0; i < table_cnt; i++) {
if (base_relative) {
long long offset;
+ int overflow;
- if (symbol_absolute(&table[i])) {
+ if (!absolute_percpu) {
+ offset = table[i].addr - relative_base;
+ overflow = (offset < 0 || offset > UINT_MAX);
+ } else if (symbol_absolute(&table[i])) {
offset = table[i].addr;
- if (offset < 0 || offset > INT_MAX) {
- fprintf(stderr, "kallsyms failure: "
- "absolute symbol value %#llx out of range in relative mode\n",
- table[i].addr);
- exit(EXIT_FAILURE);
- }
+ overflow = (offset < 0 || offset > INT_MAX);
} else {
offset = relative_base - table[i].addr - 1;
- if (offset < INT_MIN || offset >= 0) {
- fprintf(stderr, "kallsyms failure: "
- "relative symbol value %#llx out of range in relative mode\n",
- table[i].addr);
- exit(EXIT_FAILURE);
- }
+ overflow = (offset < INT_MIN || offset >= 0);
+ }
+ if (overflow) {
+ fprintf(stderr, "kallsyms failure: "
+ "%s symbol value %#llx out of range in relative mode\n",
+ symbol_absolute(&table[i]) ? "absolute" : "relative",
+ table[i].addr);
+ exit(EXIT_FAILURE);
}
printf("\t.long\t%#x\n", (int)offset);
} else if (!symbol_absolute(&table[i])) {
@@ -742,21 +743,11 @@ static void record_relative_base(void)
{
unsigned int i;
- if (kernel_start_addr > 0) {
- /*
- * If the kernel start address was specified, use that as
- * the relative base rather than going through the table,
- * since it should be a reasonable default, and values below
- * it will be ignored anyway.
- */
- relative_base = kernel_start_addr;
- } else {
- relative_base = -1ULL;
- for (i = 0; i < table_cnt; i++)
- if (!symbol_absolute(&table[i]) &&
- table[i].addr < relative_base)
- relative_base = table[i].addr;
- }
+ relative_base = -1ULL;
+ for (i = 0; i < table_cnt; i++)
+ if (!symbol_absolute(&table[i]) &&
+ table[i].addr < relative_base)
+ relative_base = table[i].addr;
}
int main(int argc, char **argv)
_
Patches currently in -mm which might be from ard.biesheuvel@xxxxxxxxxx are
extable-add-support-for-relative-extables-to-search-and-sort-routines.patch
alpha-extable-use-generic-search-and-sort-routines.patch
s390-extable-use-generic-search-and-sort-routines.patch
x86-extable-use-generic-search-and-sort-routines.patch
ia64-extable-use-generic-search-and-sort-routines.patch
arm64-switch-to-relative-exception-tables.patch
x86-kallsyms-disable-absolute-percpu-symbols-on-smp.patch
x86-kallsyms-disable-absolute-percpu-symbols-on-smp-v5.patch
kallsyms-dont-overload-absolute-symbol-type-for-percpu-symbols.patch
kallsyms-add-support-for-relative-offsets-in-kallsyms-address-table.patch
kallsyms-add-support-for-relative-offsets-in-kallsyms-address-table-v5.patch
scripts-link-vmlinuxsh-force-error-on-kallsyms-failure.patch
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