On 09/21/2016 06:32 PM, 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.
Reviewed-by: Andrew Cooper <[email protected]> [x86 bits]
Signed-off-by: Konrad Rzeszutek Wilk <[email protected]>
---
Cc: Konrad Rzeszutek Wilk <[email protected]>
Cc: Ross Lagerwall <[email protected]>
Cc: Stefano Stabellini <[email protected]>
Cc: Julien Grall <[email protected]
Cc: Jan Beulich <[email protected]>
Cc: Andrew Cooper <[email protected]>
v1: First submission
v2: Update the order of symbols, fix title
Add {} in after the first if - per Jan's recommendation.
v3: Add Andrew's Review tag
Make the function return an bool_t.
Skip check for '$t'
Fix spelling of comments.
s/arch_is_payload_symbol/arch_livepatch_symbol_ok/
v4: s/bool_t/bool/
v5: Removed an extra space in the conditional.
---
xen/arch/arm/livepatch.c | 33 +++++++++++++++++++++++++++++++++
xen/arch/x86/livepatch.c | 7 +++++++
xen/common/livepatch.c | 2 +-
xen/include/xen/livepatch.h | 2 ++
4 files changed, 43 insertions(+), 1 deletion(-)
diff --git a/xen/arch/arm/livepatch.c b/xen/arch/arm/livepatch.c
index 9284766..9959315 100644
--- a/xen/arch/arm/livepatch.c
+++ b/xen/arch/arm/livepatch.c
@@ -84,6 +84,39 @@ void arch_livepatch_unmask(void)
local_abort_enable();
}
+bool arch_livepatch_symbol_ok(const struct livepatch_elf *elf,
+ const struct livepatch_elf_sym *sym)
+{
+ /*
+ * - Mapping symbols - denote the "start of a sequence of bytes of the
+ * appropriate type" to mark certain features - such as start of region
+ * containing data ($d); ARM ($a), or A64 ($x) instructions.
+ * We ignore Thumb instructions ($t) as we shouldn't have them.
+ *
+ * The format is either short: '$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' )
This would be clear (IMO) as sym->name[0].
Either way,
Reviewed-by: Ross Lagerwall <[email protected]>
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