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Message-Id: <baef30276a799db6435989807ddbc28c2e02ea4f.1769434279.git.houwenlong.hwl@antgroup.com>
Date: Mon, 26 Jan 2026 21:33:52 +0800
From: Hou Wenlong <houwenlong.hwl@...group.com>
To: linux-kernel@...r.kernel.org
Cc: Lai Jiangshan <jiangshan.ljs@...group.com>,
Hou Wenlong <houwenlong.hwl@...group.com>,
Thomas Gleixner <tglx@...nel.org>,
Ingo Molnar <mingo@...hat.com>,
Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
x86@...nel.org,
"H. Peter Anvin" <hpa@...or.com>,
Ard Biesheuvel <ardb@...nel.org>,
Brian Gerst <brgerst@...il.com>,
Uros Bizjak <ubizjak@...il.com>
Subject: [RFC PATCH 2/5] x86/relocs: Insert relocations into input file
Add a command line option to insert relocations into a reserved section
named ".data.reloc" section of the input file. This allows for
relocation of the uncompressed kernel and is same as the implementation
in MIPS.
Signed-off-by: Hou Wenlong <houwenlong.hwl@...group.com>
---
arch/x86/tools/relocs.c | 56 ++++++++++++++++++++++++++++++----
arch/x86/tools/relocs.h | 1 +
arch/x86/tools/relocs_common.c | 13 ++++++--
3 files changed, 61 insertions(+), 9 deletions(-)
diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c
index 945d78c368f7..4d0f2bd6c35e 100644
--- a/arch/x86/tools/relocs.c
+++ b/arch/x86/tools/relocs.c
@@ -735,6 +735,17 @@ static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel,
}
}
+static struct section *sec_lookup(const char *name)
+{
+ int i;
+
+ for (i = 0; i < shnum; i++)
+ if (!strcmp(sec_name(i), name))
+ return &secs[i];
+
+ return NULL;
+}
+
#if ELF_BITS == 64
static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
@@ -950,7 +961,7 @@ static int write32_as_text(uint32_t v, FILE *f)
return fprintf(f, "\t.long 0x%08"PRIx32"\n", v) > 0 ? 0 : -1;
}
-static void emit_relocs(void)
+static void emit_relocs(FILE *f)
{
int i;
int (*write_reloc)(uint32_t, FILE *) = write32;
@@ -1001,21 +1012,54 @@ static void emit_relocs(void)
for (i = 0; i < relocs32.count; i++)
write_reloc(relocs32.offset[i], stdout);
} else {
+ FILE *outf = stdout;
+
+ if (keep_relocs) {
+ struct section *sec_reloc;
+ uint32_t size_needed;
+ unsigned long offset;
+
+ sec_reloc = sec_lookup(".data.reloc");
+ if (!sec_reloc)
+ die("Could not find relocation data section\n");
+
+ size_needed = (1 + relocs32.count) * sizeof(uint32_t);
+#if ELF_BITS == 64
+ size_needed += (1 + relocs64.count) * sizeof(uint32_t);
+#endif
+ if (size_needed > sec_reloc->shdr.sh_size)
+ die("Relocations overflow available space!\n" \
+ "Please adjust CONFIG_RELOCATION_TABLE_SIZE " \
+ "to at least 0x%08x\n", (size_needed + 0x1000) & ~0xFFF);
+
+ /*
+ * Place the relocations at the end of section to ensure
+ * compatibility with backward traversal during handling
+ * relocations.
+ */
+ offset = sec_reloc->shdr.sh_offset + sec_reloc->shdr.sh_size -
+ size_needed;
+ if (fseek(f, offset, SEEK_SET) < 0)
+ die("Seek to %ld failed: %s\n", offset, strerror(errno));
+
+ outf = f;
+ }
+
#if ELF_BITS == 64
/* Print a stop */
- write_reloc(0, stdout);
+ write_reloc(0, outf);
/* Now print each relocation */
for (i = 0; i < relocs64.count; i++)
- write_reloc(relocs64.offset[i], stdout);
+ write_reloc(relocs64.offset[i], outf);
#endif
/* Print a stop */
- write_reloc(0, stdout);
+ write_reloc(0, outf);
/* Now print each relocation */
for (i = 0; i < relocs32.count; i++)
- write_reloc(relocs32.offset[i], stdout);
+ write_reloc(relocs32.offset[i], outf);
}
}
@@ -1073,5 +1117,5 @@ void process(FILE *fp)
return;
}
- emit_relocs();
+ emit_relocs(fp);
}
diff --git a/arch/x86/tools/relocs.h b/arch/x86/tools/relocs.h
index 5ade07ac2754..05a6e80e815a 100644
--- a/arch/x86/tools/relocs.h
+++ b/arch/x86/tools/relocs.h
@@ -35,6 +35,7 @@ extern int show_absolute_relocs;
extern int show_reloc_info;
extern int as_text;
extern int use_real_mode;
+extern int keep_relocs;
void process_32(FILE *fp);
void process_64(FILE *fp);
diff --git a/arch/x86/tools/relocs_common.c b/arch/x86/tools/relocs_common.c
index ee8a9fafcb11..66a9a83b7395 100644
--- a/arch/x86/tools/relocs_common.c
+++ b/arch/x86/tools/relocs_common.c
@@ -2,7 +2,7 @@
#include "relocs.h"
int show_absolute_syms, show_absolute_relocs, show_reloc_info;
-int as_text, use_real_mode;
+int as_text, use_real_mode, keep_relocs;
void die(char *fmt, ...)
{
@@ -15,7 +15,7 @@ void die(char *fmt, ...)
static void usage(void)
{
- die("relocs [--abs-syms|--abs-relocs|--reloc-info|--text|--realmode]" \
+ die("relocs [--abs-syms|--abs-relocs|--reloc-info|--text|--realmode|--keep]" \
" vmlinux\n");
}
@@ -55,6 +55,10 @@ int main(int argc, char **argv)
use_real_mode = 1;
continue;
}
+ if (strcmp(arg, "--keep") == 0) {
+ keep_relocs = 1;
+ continue;
+ }
}
else if (!fname) {
fname = arg;
@@ -65,7 +69,10 @@ int main(int argc, char **argv)
if (!fname) {
usage();
}
- fp = fopen(fname, "r");
+ if (keep_relocs)
+ fp = fopen(fname, "r+");
+ else
+ fp = fopen(fname, "r");
if (!fp) {
die("Cannot open %s: %s\n", fname, strerror(errno));
}
--
2.31.1
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