On Fri, Dec 25, 2020 at 06:50:33PM +0800, kernel test robot wrote:
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <l...@intel.com>
>
> All warnings (new ones prefixed by >>):
>
> >> arch/x86/kernel/sev-es.c:258:7: warning: variable 'ret' is used
> >> uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
> if (!insn_decode_regs(&ctxt->insn, ctxt->regs, buffer,
> res))
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Yeah, good catch, thanks for reporting.
Frankly, the readability and "extensiblity" of that function can be
improved by splitting the two cases (diff ontop):
---
diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c
index 564cc9fc693d..ea47037f1624 100644
--- a/arch/x86/kernel/sev-es.c
+++ b/arch/x86/kernel/sev-es.c
@@ -241,40 +241,53 @@ static int vc_fetch_insn_kernel(struct es_em_ctxt *ctxt,
return copy_from_kernel_nofault(buffer, (unsigned char
*)ctxt->regs->ip, MAX_INSN_SIZE);
}
-static enum es_result vc_decode_insn(struct es_em_ctxt *ctxt)
+static enum es_result __vc_decode_user_insn(struct es_em_ctxt *ctxt)
{
char buffer[MAX_INSN_SIZE];
- int res, ret;
-
- if (user_mode(ctxt->regs)) {
- res = insn_fetch_from_user(ctxt->regs, buffer);
- if (!res) {
- ctxt->fi.vector = X86_TRAP_PF;
- ctxt->fi.error_code = X86_PF_INSTR | X86_PF_USER;
- ctxt->fi.cr2 = ctxt->regs->ip;
- return ES_EXCEPTION;
- }
+ int res;
- if (!insn_decode_regs(&ctxt->insn, ctxt->regs, buffer, res))
- return ES_DECODE_FAILED;
- } else {
- res = vc_fetch_insn_kernel(ctxt, buffer);
- if (res) {
- ctxt->fi.vector = X86_TRAP_PF;
- ctxt->fi.error_code = X86_PF_INSTR;
- ctxt->fi.cr2 = ctxt->regs->ip;
- return ES_EXCEPTION;
- }
+ res = insn_fetch_from_user(ctxt->regs, buffer);
+ if (!res) {
+ ctxt->fi.vector = X86_TRAP_PF;
+ ctxt->fi.error_code = X86_PF_INSTR | X86_PF_USER;
+ ctxt->fi.cr2 = ctxt->regs->ip;
+ return ES_EXCEPTION;
+ }
+
+ if (!insn_decode_regs(&ctxt->insn, ctxt->regs, buffer, res))
+ return ES_DECODE_FAILED;
+ else
+ return ES_OK;
+}
+
+static enum es_result __vc_decode_kern_insn(struct es_em_ctxt *ctxt)
+{
+ char buffer[MAX_INSN_SIZE];
+ int res;
- ret = insn_decode(&ctxt->insn, buffer, MAX_INSN_SIZE - res,
INSN_MODE_64);
+ res = vc_fetch_insn_kernel(ctxt, buffer);
+ if (res) {
+ ctxt->fi.vector = X86_TRAP_PF;
+ ctxt->fi.error_code = X86_PF_INSTR;
+ ctxt->fi.cr2 = ctxt->regs->ip;
+ return ES_EXCEPTION;
}
- if (ret < 0)
+ res = insn_decode(&ctxt->insn, buffer, MAX_INSN_SIZE - res,
INSN_MODE_64);
+ if (res < 0)
return ES_DECODE_FAILED;
else
return ES_OK;
}
+static enum es_result vc_decode_insn(struct es_em_ctxt *ctxt)
+{
+ if (user_mode(ctxt->regs))
+ return __vc_decode_user_insn(ctxt);
+ else
+ return __vc_decode_kern_insn(ctxt);
+}
+
static enum es_result vc_write_mem(struct es_em_ctxt *ctxt,
char *dst, char *buf, size_t size)
{
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
