Hi Konrad,
On 25/08/16 14:37, Konrad Rzeszutek Wilk wrote:
Those symbols are used to help final linkers to replace insn.
The ARM ELF specification mandates that they are present
to denote the start of certain CPU features. There are two
variants of it - short and long format.
Either way - we can ignore these symbols.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
---
Cc: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
Cc: Ross Lagerwall <ross.lagerw...@citrix.com>
Cc: Stefano Stabellini <sstabell...@kernel.org>
Cc: Julien Grall <julien.gr...@arm.com
Cc: Jan Beulich <jbeul...@suse.com>
Cc: Andrew Cooper <andrew.coop...@citrix.com>
v1: First submission
v2: Update the order of symbols, fix title
Add {} in after the first if - per Jan's recommendation.
---
xen/arch/arm/livepatch.c | 32 ++++++++++++++++++++++++++++++++
xen/arch/x86/livepatch.c | 7 +++++++
xen/common/livepatch.c | 2 +-
xen/include/xen/livepatch.h | 2 ++
4 files changed, 42 insertions(+), 1 deletion(-)
diff --git a/xen/arch/arm/livepatch.c b/xen/arch/arm/livepatch.c
index f49e347..c290602 100644
--- a/xen/arch/arm/livepatch.c
+++ b/xen/arch/arm/livepatch.c
@@ -82,6 +82,38 @@ void arch_livepatch_unmask(void)
local_abort_enable();
}
+int arch_is_payload_symbol(const struct livepatch_elf *elf,
+ const struct livepatch_elf_sym *sym)
I think this function should return bool (or bool_t) as the return will
be used by is_payload_symbol as bool.
+{
+ /*
+ * - Mapping symbols - denote the "start of a sequence of bytes of the
+ * appropiate type" to mark certain features - such as start of region
s/appropiate/appropriate/
+ * containing data ($d); ARM ($a), A64 ($x), or Thumb instructions ($t).
+ *
+ * The format is either short: '$x' or long: '$x.<any>'. We do not
+ * need this and more importantly - each payload will contain this
+ * resulting in symbol collisions.
+ */
+ if ( *sym->name == '$' && sym->name[1] != '\0' )
+ {
+ char p = sym->name[1];
+ size_t len = strlen(sym->name);
+
+ if ( (len >= 3 && ( sym->name[2] == '.' )) || (len == 2) )
+ {
+ if ( p == 'd' ||
+#ifdef CONFIG_ARM_32
+ p == 'a' || p == 't'
Note that Xen is not using Thumb instructions which have variable
length, so we shouldn't expect to see $t. symbols.
+#else
+ p == 'x'
+#endif
+ )
+ return 0;
Please use false here.
+ }
+ }
+ return 1;
Please use true here.
+}
+
Regards,
--
Julien Grall
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