All code and dat from this file will go into a text section
which we want to not be writeable.
Signed-off-by: Frediano Ziglio <frediano.ziglio@cloud.com>
---
xen/arch/x86/boot/reloc.c | 62 ++++++++++++++++++++-------------------
1 file changed, 32 insertions(+), 30 deletions(-)
diff --git a/xen/arch/x86/boot/reloc.c b/xen/arch/x86/boot/reloc.c
index 201e38d544..de8487483a 100644
--- a/xen/arch/x86/boot/reloc.c
+++ b/xen/arch/x86/boot/reloc.c
@@ -72,11 +72,13 @@ struct vesa_mode_info {
#define get_mb2_data(tag, type, member) (((const multiboot2_tag_##type##_t *)(tag))->member)
#define get_mb2_string(tag, type, member) ((uint32_t)get_mb2_data(tag, type, member))
-static uint32_t alloc;
+typedef struct memctx {
+ uint32_t alloc;
+} memctx;
-static uint32_t alloc_mem(uint32_t bytes)
+static uint32_t alloc_mem(uint32_t bytes, memctx *ctx)
{
- return alloc -= ROUNDUP(bytes, 16);
+ return ctx->alloc -= ROUNDUP(bytes, 16);
}
static void zero_mem(uint32_t s, uint32_t bytes)
@@ -85,11 +87,11 @@ static void zero_mem(uint32_t s, uint32_t bytes)
*(char *)s++ = 0;
}
-static uint32_t copy_mem(uint32_t src, uint32_t bytes)
+static uint32_t copy_mem(uint32_t src, uint32_t bytes, memctx *ctx)
{
uint32_t dst, dst_ret;
- dst = alloc_mem(bytes);
+ dst = alloc_mem(bytes, ctx);
dst_ret = dst;
while ( bytes-- )
@@ -98,7 +100,7 @@ static uint32_t copy_mem(uint32_t src, uint32_t bytes)
return dst_ret;
}
-static uint32_t copy_string(uint32_t src)
+static uint32_t copy_string(uint32_t src, memctx *ctx)
{
uint32_t p;
@@ -108,17 +110,17 @@ static uint32_t copy_string(uint32_t src)
for ( p = src; *(char *)p != '\0'; p++ )
continue;
- return copy_mem(src, p - src + 1);
+ return copy_mem(src, p - src + 1, ctx);
}
-static struct hvm_start_info *pvh_info_reloc(uint32_t in)
+static struct hvm_start_info *pvh_info_reloc(uint32_t in, memctx *ctx)
{
struct hvm_start_info *out;
- out = _p(copy_mem(in, sizeof(*out)));
+ out = _p(copy_mem(in, sizeof(*out), ctx));
if ( out->cmdline_paddr )
- out->cmdline_paddr = copy_string(out->cmdline_paddr);
+ out->cmdline_paddr = copy_string(out->cmdline_paddr, ctx);
if ( out->nr_modules )
{
@@ -127,51 +129,51 @@ static struct hvm_start_info *pvh_info_reloc(uint32_t in)
out->modlist_paddr =
copy_mem(out->modlist_paddr,
- out->nr_modules * sizeof(struct hvm_modlist_entry));
+ out->nr_modules * sizeof(struct hvm_modlist_entry), ctx);
mods = _p(out->modlist_paddr);
for ( i = 0; i < out->nr_modules; i++ )
{
if ( mods[i].cmdline_paddr )
- mods[i].cmdline_paddr = copy_string(mods[i].cmdline_paddr);
+ mods[i].cmdline_paddr = copy_string(mods[i].cmdline_paddr, ctx);
}
}
return out;
}
-static multiboot_info_t *mbi_reloc(uint32_t mbi_in)
+static multiboot_info_t *mbi_reloc(uint32_t mbi_in, memctx *ctx)
{
int i;
multiboot_info_t *mbi_out;
- mbi_out = _p(copy_mem(mbi_in, sizeof(*mbi_out)));
+ mbi_out = _p(copy_mem(mbi_in, sizeof(*mbi_out), ctx));
if ( mbi_out->flags & MBI_CMDLINE )
- mbi_out->cmdline = copy_string(mbi_out->cmdline);
+ mbi_out->cmdline = copy_string(mbi_out->cmdline, ctx);
if ( mbi_out->flags & MBI_MODULES )
{
module_t *mods;
mbi_out->mods_addr = copy_mem(mbi_out->mods_addr,
- mbi_out->mods_count * sizeof(module_t));
+ mbi_out->mods_count * sizeof(module_t), ctx);
mods = _p(mbi_out->mods_addr);
for ( i = 0; i < mbi_out->mods_count; i++ )
{
if ( mods[i].string )
- mods[i].string = copy_string(mods[i].string);
+ mods[i].string = copy_string(mods[i].string, ctx);
}
}
if ( mbi_out->flags & MBI_MEMMAP )
- mbi_out->mmap_addr = copy_mem(mbi_out->mmap_addr, mbi_out->mmap_length);
+ mbi_out->mmap_addr = copy_mem(mbi_out->mmap_addr, mbi_out->mmap_length, ctx);
if ( mbi_out->flags & MBI_LOADERNAME )
- mbi_out->boot_loader_name = copy_string(mbi_out->boot_loader_name);
+ mbi_out->boot_loader_name = copy_string(mbi_out->boot_loader_name, ctx);
/* Mask features we don't understand or don't relocate. */
mbi_out->flags &= (MBI_MEMLIMITS |
@@ -183,7 +185,7 @@ static multiboot_info_t *mbi_reloc(uint32_t mbi_in)
return mbi_out;
}
-static multiboot_info_t *mbi2_reloc(uint32_t mbi_in, uint32_t video_out)
+static multiboot_info_t *mbi2_reloc(uint32_t mbi_in, uint32_t video_out, memctx *ctx)
{
const multiboot2_fixed_t *mbi_fix = _p(mbi_in);
const multiboot2_memory_map_t *mmap_src;
@@ -197,7 +199,7 @@ static multiboot_info_t *mbi2_reloc(uint32_t mbi_in, uint32_t video_out)
uint32_t ptr;
unsigned int i, mod_idx = 0;
- ptr = alloc_mem(sizeof(*mbi_out));
+ ptr = alloc_mem(sizeof(*mbi_out), ctx);
mbi_out = _p(ptr);
zero_mem(ptr, sizeof(*mbi_out));
@@ -222,7 +224,7 @@ static multiboot_info_t *mbi2_reloc(uint32_t mbi_in, uint32_t video_out)
* __start_xen() may put Xen image placement into it.
*/
mbi_out->mods_addr = alloc_mem((mbi_out->mods_count + 1) *
- sizeof(*mbi_out_mods));
+ sizeof(*mbi_out_mods), ctx);
mbi_out_mods = _p(mbi_out->mods_addr);
}
@@ -238,13 +240,13 @@ static multiboot_info_t *mbi2_reloc(uint32_t mbi_in, uint32_t video_out)
case MULTIBOOT2_TAG_TYPE_BOOT_LOADER_NAME:
mbi_out->flags |= MBI_LOADERNAME;
ptr = get_mb2_string(tag, string, string);
- mbi_out->boot_loader_name = copy_string(ptr);
+ mbi_out->boot_loader_name = copy_string(ptr, ctx);
break;
case MULTIBOOT2_TAG_TYPE_CMDLINE:
mbi_out->flags |= MBI_CMDLINE;
ptr = get_mb2_string(tag, string, string);
- mbi_out->cmdline = copy_string(ptr);
+ mbi_out->cmdline = copy_string(ptr, ctx);
break;
case MULTIBOOT2_TAG_TYPE_BASIC_MEMINFO:
@@ -263,7 +265,7 @@ static multiboot_info_t *mbi2_reloc(uint32_t mbi_in, uint32_t video_out)
mbi_out->mmap_length /= get_mb2_data(tag, mmap, entry_size);
mbi_out->mmap_length *= sizeof(*mmap_dst);
- mbi_out->mmap_addr = alloc_mem(mbi_out->mmap_length);
+ mbi_out->mmap_addr = alloc_mem(mbi_out->mmap_length, ctx);
mmap_src = get_mb2_data(tag, mmap, entries);
mmap_dst = _p(mbi_out->mmap_addr);
@@ -290,7 +292,7 @@ static multiboot_info_t *mbi2_reloc(uint32_t mbi_in, uint32_t video_out)
mbi_out_mods[mod_idx].mod_start = get_mb2_data(tag, module, mod_start);
mbi_out_mods[mod_idx].mod_end = get_mb2_data(tag, module, mod_end);
ptr = get_mb2_string(tag, module, cmdline);
- mbi_out_mods[mod_idx].string = copy_string(ptr);
+ mbi_out_mods[mod_idx].string = copy_string(ptr, ctx);
mbi_out_mods[mod_idx].reserved = 0;
++mod_idx;
break;
@@ -356,19 +358,19 @@ static multiboot_info_t *mbi2_reloc(uint32_t mbi_in, uint32_t video_out)
void *reloc(uint32_t magic, uint32_t in, uint32_t trampoline,
uint32_t video_info)
{
- alloc = trampoline;
+ memctx ctx = { trampoline };
switch ( magic )
{
case MULTIBOOT_BOOTLOADER_MAGIC:
- return mbi_reloc(in);
+ return mbi_reloc(in, &ctx);
case MULTIBOOT2_BOOTLOADER_MAGIC:
- return mbi2_reloc(in, video_info);
+ return mbi2_reloc(in, video_info, &ctx);
case XEN_HVM_START_MAGIC_VALUE:
if ( IS_ENABLED(CONFIG_PVH_GUEST) )
- return pvh_info_reloc(in);
+ return pvh_info_reloc(in, &ctx);
/* Fallthrough */
default:
--
2.46.0On 04/09/2024 3:56 pm, Frediano Ziglio wrote:
> All code and dat from this file will go into a text section
> which we want to not be writeable.
Getting data out of the instruction cache is a good thing, but
writeability isn't relevant here. This logic only executes in 32bit
unpaged mode.
>
> Signed-off-by: Frediano Ziglio <frediano.ziglio@cloud.com>
> ---
> xen/arch/x86/boot/reloc.c | 62 ++++++++++++++++++++-------------------
> 1 file changed, 32 insertions(+), 30 deletions(-)
>
> diff --git a/xen/arch/x86/boot/reloc.c b/xen/arch/x86/boot/reloc.c
> index 201e38d544..de8487483a 100644
> --- a/xen/arch/x86/boot/reloc.c
> +++ b/xen/arch/x86/boot/reloc.c
> @@ -72,11 +72,13 @@ struct vesa_mode_info {
> #define get_mb2_data(tag, type, member) (((const multiboot2_tag_##type##_t *)(tag))->member)
> #define get_mb2_string(tag, type, member) ((uint32_t)get_mb2_data(tag, type, member))
>
> -static uint32_t alloc;
> +typedef struct memctx {
> + uint32_t alloc;
> +} memctx;
Can we take the opportunity to rename alloc to ptr, and have a comment
explaining how this works
/* Simple bump allocator. It starts from the base of the trampoline and
allocates downwards. */
Happy to fix up on commit.
~Andrew
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