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x86/mce: Prevent severity computation from being instrumented

Browse source 
Mark all the MCE severity computation logic noinstr and allow
instrumentation when it "calls out".

Fixes

  vmlinux.o: warning: objtool: do_machine_check()+0xc5d: call to mce_severity() leaves .noinstr.text section

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211208111343.8130-7-bp@alien8.de
This commit is contained in:
Borislav Petkov 2021-10-13 09:47:50 +02:00
parent 4fbce464db
commit 0a5b288e85
1 changed files with 21 additions and 9 deletions
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30
arch/x86/kernel/cpu/mce/severity.c
View file

@ -263,24 +263,36 @@ static bool is_copy_from_user(struct pt_regs *regs)
* distinguish an exception taken in user from from one
* taken in the kernel.
*/
static int error_context(struct mce *m, struct pt_regs *regs)
static noinstr int error_context(struct mce *m, struct pt_regs *regs)
{
int fixup_type;
bool copy_user;
if ((m->cs & 3) == 3)
return IN_USER;
if (!mc_recoverable(m->mcgstatus))
return IN_KERNEL;
switch (ex_get_fixup_type(m->ip)) {
/* Allow instrumentation around external facilities usage. */
instrumentation_begin();
fixup_type = ex_get_fixup_type(m->ip);
copy_user = is_copy_from_user(regs);
instrumentation_end();
switch (fixup_type) {
case EX_TYPE_UACCESS:
case EX_TYPE_COPY:
if (!regs || !is_copy_from_user(regs))
if (!regs || !copy_user)
return IN_KERNEL;
m->kflags |= MCE_IN_KERNEL_COPYIN;
fallthrough;
case EX_TYPE_FAULT_MCE_SAFE:
case EX_TYPE_DEFAULT_MCE_SAFE:
m->kflags |= MCE_IN_KERNEL_RECOV;
return IN_KERNEL_RECOV;
default:
return IN_KERNEL;
}
@ -315,8 +327,8 @@ static int mce_severity_amd_smca(struct mce *m, enum context err_ctx)
* See AMD Error Scope Hierarchy table in a newer BKDG. For example
* 49125_15h_Models_30h-3Fh_BKDG.pdf, section "RAS Features"
*/
static int mce_severity_amd(struct mce *m, struct pt_regs *regs, int tolerant,
char **msg, bool is_excp)
static noinstr int mce_severity_amd(struct mce *m, struct pt_regs *regs, int tolerant,
char **msg, bool is_excp)
{
enum context ctx = error_context(m, regs);
@ -368,8 +380,8 @@ static int mce_severity_amd(struct mce *m, struct pt_regs *regs, int tolerant,
return MCE_KEEP_SEVERITY;
}
static int mce_severity_intel(struct mce *m, struct pt_regs *regs,
int tolerant, char **msg, bool is_excp)
static noinstr int mce_severity_intel(struct mce *m, struct pt_regs *regs,
int tolerant, char **msg, bool is_excp)
{
enum exception excp = (is_excp ? EXCP_CONTEXT : NO_EXCP);
enum context ctx = error_context(m, regs);
@ -405,8 +417,8 @@ static int mce_severity_intel(struct mce *m, struct pt_regs *regs,
}
}
int mce_severity(struct mce *m, struct pt_regs *regs, int tolerant, char **msg,
bool is_excp)
int noinstr mce_severity(struct mce *m, struct pt_regs *regs, int tolerant, char **msg,
bool is_excp)
{
if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)