[PATCH v2 06/11] kexec_file: Split up __kexec_load_puragory
Philipp Rudo
prudo at linux.vnet.ibm.com
Wed Mar 21 04:27:46 PDT 2018
When inspecting __kexec_load_purgatory you find that it has two tasks
1) setting up the kexec_buffer for the new kernel and,
2) setting up pi->sechdrs for the final load address.
The two tasks are independent of each other. To improve readability split
up __kexec_load_purgatory into two functions, one for each task, and call
them directly from kexec_load_purgatory.
Signed-off-by: Philipp Rudo <prudo at linux.vnet.ibm.com>
---
kernel/kexec_file.c | 200 +++++++++++++++++++++++++++-------------------------
1 file changed, 103 insertions(+), 97 deletions(-)
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 80c7f658afc0..d1c3ec8dc6b1 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -649,39 +649,97 @@ static int kexec_calculate_store_digests(struct kimage *image)
return ret;
}
-/* Actually load purgatory. Lot of code taken from kexec-tools */
-static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
- unsigned long max, int top_down)
+/*
+ * kexec_purgatory_setup_kbuf - prepare buffer to load purgatory.
+ * @pi: Purgatory to be loaded.
+ * @kbuf: Buffer to setup.
+ *
+ * Allocates the memory needed for the buffer. Caller is responsible to free
+ * the memory after use.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
+static int kexec_purgatory_setup_kbuf(struct purgatory_info *pi,
+ struct kexec_buf *kbuf)
{
- struct purgatory_info *pi = &image->purgatory_info;
- unsigned long align, bss_align, bss_sz, bss_pad;
- unsigned long entry, load_addr, curr_load_addr, bss_addr, offset;
- unsigned char *buf_addr, *src;
- int i, ret = 0, entry_sidx = -1;
- const Elf_Shdr *sechdrs_c;
- Elf_Shdr *sechdrs = NULL;
- struct kexec_buf kbuf = { .image = image, .bufsz = 0, .buf_align = 1,
- .buf_min = min, .buf_max = max,
- .top_down = top_down };
+ const Elf_Shdr *sechdrs;
+ unsigned long bss_align;
+ unsigned long bss_sz;
+ unsigned long align;
+ int i, ret;
- /*
- * sechdrs_c points to section headers in purgatory and are read
- * only. No modifications allowed.
- */
- sechdrs_c = (void *)pi->ehdr + pi->ehdr->e_shoff;
+ sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
+ bss_align = 1;
+ bss_sz = 0;
+
+ for (i = 0; i < pi->ehdr->e_shnum; i++) {
+ if (!(sechdrs[i].sh_flags & SHF_ALLOC))
+ continue;
+
+ align = sechdrs[i].sh_addralign;
+ if (sechdrs[i].sh_type != SHT_NOBITS) {
+ if (kbuf->buf_align < align)
+ kbuf->buf_align = align;
+ kbuf->bufsz = ALIGN(kbuf->bufsz, align);
+ kbuf->bufsz += sechdrs[i].sh_size;
+ } else {
+ if (bss_align < align)
+ bss_align = align;
+ bss_sz = ALIGN(bss_sz, align);
+ bss_sz += sechdrs[i].sh_size;
+ }
+ }
+ kbuf->bufsz = ALIGN(kbuf->bufsz, bss_align);
+ kbuf->memsz = kbuf->bufsz + bss_sz;
+ if (kbuf->buf_align < bss_align)
+ kbuf->buf_align = bss_align;
+
+ kbuf->buffer = vzalloc(kbuf->bufsz);
+ if (!kbuf->buffer)
+ return -ENOMEM;
+ pi->purgatory_buf = kbuf->buffer;
+
+ ret = kexec_add_buffer(kbuf);
+ if (ret)
+ goto out;
+ pi->purgatory_load_addr = kbuf->mem;
+
+ return 0;
+out:
+ vfree(pi->purgatory_buf);
+ pi->purgatory_buf = NULL;
+ return ret;
+}
+
+/*
+ * kexec_purgatory_setup_sechdrs - prepares the pi->sechdrs buffer.
+ * @pi: Purgatory to be loaded.
+ * @kbuf: Buffer prepared to store purgatory.
+ *
+ * Allocates the memory needed for the buffer. Caller is responsible to free
+ * the memory after use.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
+static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi,
+ struct kexec_buf *kbuf)
+{
+ unsigned long curr_load_addr;
+ unsigned long load_addr;
+ unsigned long bss_addr;
+ unsigned long offset;
+ unsigned char *buf_addr;
+ unsigned char *src;
+ Elf_Shdr *sechdrs;
+ int entry_sidx = -1;
+ int i;
- /*
- * We can not modify sechdrs_c[] and its fields. It is read only.
- * Copy it over to a local copy where one can store some temporary
- * data and free it at the end. We need to modify ->sh_addr and
- * ->sh_offset fields to keep track of permanent and temporary
- * locations of sections.
- */
sechdrs = vzalloc(pi->ehdr->e_shnum * sizeof(Elf_Shdr));
if (!sechdrs)
return -ENOMEM;
-
- memcpy(sechdrs, sechdrs_c, pi->ehdr->e_shnum * sizeof(Elf_Shdr));
+ memcpy(sechdrs, (void *)pi->ehdr + pi->ehdr->e_shoff,
+ pi->ehdr->e_shnum * sizeof(Elf_Shdr));
+ pi->sechdrs = sechdrs;
/*
* We seem to have multiple copies of sections. First copy is which
@@ -709,7 +767,7 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
* Identify entry point section and make entry relative to section
* start.
*/
- entry = pi->ehdr->e_entry;
+ kbuf->image->start = pi->ehdr->e_entry;
for (i = 0; i < pi->ehdr->e_shnum; i++) {
if (!(sechdrs[i].sh_flags & SHF_ALLOC))
continue;
@@ -722,63 +780,19 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
((sechdrs[i].sh_addr + sechdrs[i].sh_size) >
pi->ehdr->e_entry)) {
entry_sidx = i;
- entry -= sechdrs[i].sh_addr;
+ kbuf->image->start -= sechdrs[i].sh_addr;
break;
}
}
- /* Determine how much memory is needed to load relocatable object. */
- bss_align = 1;
- bss_sz = 0;
-
- for (i = 0; i < pi->ehdr->e_shnum; i++) {
- if (!(sechdrs[i].sh_flags & SHF_ALLOC))
- continue;
-
- align = sechdrs[i].sh_addralign;
- if (sechdrs[i].sh_type != SHT_NOBITS) {
- if (kbuf.buf_align < align)
- kbuf.buf_align = align;
- kbuf.bufsz = ALIGN(kbuf.bufsz, align);
- kbuf.bufsz += sechdrs[i].sh_size;
- } else {
- /* bss section */
- if (bss_align < align)
- bss_align = align;
- bss_sz = ALIGN(bss_sz, align);
- bss_sz += sechdrs[i].sh_size;
- }
- }
-
- /* Determine the bss padding required to align bss properly */
- bss_pad = 0;
- if (kbuf.bufsz & (bss_align - 1))
- bss_pad = bss_align - (kbuf.bufsz & (bss_align - 1));
-
- kbuf.memsz = kbuf.bufsz + bss_pad + bss_sz;
-
- /* Allocate buffer for purgatory */
- kbuf.buffer = vzalloc(kbuf.bufsz);
- if (!kbuf.buffer) {
- ret = -ENOMEM;
- goto out;
- }
-
- if (kbuf.buf_align < bss_align)
- kbuf.buf_align = bss_align;
-
- /* Add buffer to segment list */
- ret = kexec_add_buffer(&kbuf);
- if (ret)
- goto out;
- pi->purgatory_load_addr = kbuf.mem;
-
/* Load SHF_ALLOC sections */
- buf_addr = kbuf.buffer;
- load_addr = curr_load_addr = pi->purgatory_load_addr;
- bss_addr = load_addr + kbuf.bufsz + bss_pad;
+ buf_addr = kbuf->buffer;
+ load_addr = curr_load_addr = kbuf->mem;
+ bss_addr = load_addr + kbuf->bufsz;
for (i = 0; i < pi->ehdr->e_shnum; i++) {
+ unsigned long align;
+
if (!(sechdrs[i].sh_flags & SHF_ALLOC))
continue;
@@ -810,24 +824,9 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
/* Update entry point based on load address of text section */
if (entry_sidx >= 0)
- entry += sechdrs[entry_sidx].sh_addr;
-
- /* Make kernel jump to purgatory after shutdown */
- image->start = entry;
-
- /* Used later to get/set symbol values */
- pi->sechdrs = sechdrs;
+ kbuf->image->start += sechdrs[entry_sidx].sh_addr;
- /*
- * Used later to identify which section is purgatory and skip it
- * from checksumming.
- */
- pi->purgatory_buf = kbuf.buffer;
- return ret;
-out:
- vfree(sechdrs);
- vfree(kbuf.buffer);
- return ret;
+ return 0;
}
static int kexec_apply_relocations(struct kimage *image)
@@ -897,16 +896,23 @@ int kexec_load_purgatory(struct kimage *image, unsigned long min,
{
struct purgatory_info *pi = &image->purgatory_info;
int ret;
+ struct kexec_buf kbuf = { .image = image, .bufsz = 0, .buf_align = 1,
+ .buf_min = min, .buf_max = max,
+ .top_down = top_down };
if (kexec_purgatory_size <= 0)
return -EINVAL;
pi->ehdr = (const Elf_Ehdr *)kexec_purgatory;
- ret = __kexec_load_purgatory(image, min, max, top_down);
+ ret = kexec_purgatory_setup_kbuf(pi, &kbuf);
if (ret)
return ret;
+ ret = kexec_purgatory_setup_sechdrs(pi, &kbuf);
+ if (ret)
+ goto out_free_kbuf;
+
ret = kexec_apply_relocations(image);
if (ret)
goto out;
@@ -916,7 +922,7 @@ int kexec_load_purgatory(struct kimage *image, unsigned long min,
out:
vfree(pi->sechdrs);
pi->sechdrs = NULL;
-
+out_free_kbuf:
vfree(pi->purgatory_buf);
pi->purgatory_buf = NULL;
return ret;
--
2.13.5
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