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authorJoerg Roedel <jroedel@suse.de>2021-06-14 15:53:26 +0200
committerBorislav Petkov <bp@suse.de>2021-06-15 11:39:30 +0200
commit4aaa7eacd7cc7c10f269c7f2a01d044b375bed8e (patch)
treee5b872baed73de2090cde3ac4a696bbfe9c20ab1 /arch
parentf2df15639e44d23bf82a86a03092472c7278cd39 (diff)
x86/insn: Extend error reporting from insn_fetch_from_user[_inatomic]()
The error reporting from the insn_fetch_from_user*() functions is not very verbose. Extend it to include information on whether the linear RIP could not be calculated or whether the memory access faulted. This will be used in the SEV-ES code to propagate the correct exception depending on what went wrong during instruction fetch. [ bp: Massage comments. ] Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20210614135327.9921-6-joro@8bytes.org
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/sev.c8
-rw-r--r--arch/x86/kernel/umip.c10
-rw-r--r--arch/x86/lib/insn-eval.c16
3 files changed, 16 insertions, 18 deletions
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 4fd997bbf059..a1eeaa79bf2b 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -258,17 +258,17 @@ static int vc_fetch_insn_kernel(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;
+ int insn_bytes;
- res = insn_fetch_from_user_inatomic(ctxt->regs, buffer);
- if (!res) {
+ insn_bytes = insn_fetch_from_user_inatomic(ctxt->regs, buffer);
+ if (insn_bytes <= 0) {
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_from_regs(&ctxt->insn, ctxt->regs, buffer, res))
+ if (!insn_decode_from_regs(&ctxt->insn, ctxt->regs, buffer, insn_bytes))
return ES_DECODE_FAILED;
if (ctxt->insn.immediate.got)
diff --git a/arch/x86/kernel/umip.c b/arch/x86/kernel/umip.c
index 8daa70b0d2da..576b47e7523d 100644
--- a/arch/x86/kernel/umip.c
+++ b/arch/x86/kernel/umip.c
@@ -346,14 +346,12 @@ bool fixup_umip_exception(struct pt_regs *regs)
if (!regs)
return false;
- nr_copied = insn_fetch_from_user(regs, buf);
-
/*
- * The insn_fetch_from_user above could have failed if user code
- * is protected by a memory protection key. Give up on emulation
- * in such a case. Should we issue a page fault?
+ * Give up on emulation if fetching the instruction failed. Should a
+ * page fault or a #GP be issued?
*/
- if (!nr_copied)
+ nr_copied = insn_fetch_from_user(regs, buf);
+ if (nr_copied <= 0)
return false;
if (!insn_decode_from_regs(&insn, regs, buf, nr_copied))
diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c
index 4eecb9c7c6a0..a1d24fdc07cf 100644
--- a/arch/x86/lib/insn-eval.c
+++ b/arch/x86/lib/insn-eval.c
@@ -1448,9 +1448,9 @@ static int insn_get_effective_ip(struct pt_regs *regs, unsigned long *ip)
*
* Returns:
*
- * Number of instruction bytes copied.
- *
- * 0 if nothing was copied.
+ * - number of instruction bytes copied.
+ * - 0 if nothing was copied.
+ * - -EINVAL if the linear address of the instruction could not be calculated
*/
int insn_fetch_from_user(struct pt_regs *regs, unsigned char buf[MAX_INSN_SIZE])
{
@@ -1458,7 +1458,7 @@ int insn_fetch_from_user(struct pt_regs *regs, unsigned char buf[MAX_INSN_SIZE])
int not_copied;
if (insn_get_effective_ip(regs, &ip))
- return 0;
+ return -EINVAL;
not_copied = copy_from_user(buf, (void __user *)ip, MAX_INSN_SIZE);
@@ -1476,9 +1476,9 @@ int insn_fetch_from_user(struct pt_regs *regs, unsigned char buf[MAX_INSN_SIZE])
*
* Returns:
*
- * Number of instruction bytes copied.
- *
- * 0 if nothing was copied.
+ * - number of instruction bytes copied.
+ * - 0 if nothing was copied.
+ * - -EINVAL if the linear address of the instruction could not be calculated.
*/
int insn_fetch_from_user_inatomic(struct pt_regs *regs, unsigned char buf[MAX_INSN_SIZE])
{
@@ -1486,7 +1486,7 @@ int insn_fetch_from_user_inatomic(struct pt_regs *regs, unsigned char buf[MAX_IN
int not_copied;
if (insn_get_effective_ip(regs, &ip))
- return 0;
+ return -EINVAL;
not_copied = __copy_from_user_inatomic(buf, (void __user *)ip, MAX_INSN_SIZE);