diff options
| author |   Peter Zijlstra <peterz@infradead.org> | 2022-06-17 16:52:06 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-07-21 10:39:42 +0200 |
| commit | a1a5482a2c6e38a3ebed32e571625c56a8cc41a6 (patch) | |
| tree | 3e28a46b39fd5eea83ead15614b670e523a24876 /arch/x86/mm/extable.c | |
| parent | x86,nospec: Simplify {JMP,CALL}_NOSPEC (diff) | |
| download | linux-dev-a1a5482a2c6e38a3ebed32e571625c56a8cc41a6.tar.xz linux-dev-a1a5482a2c6e38a3ebed32e571625c56a8cc41a6.zip | |
x86/extable: Fix ex_handler_msr() print condition
On Fri, Jun 17, 2022 at 02:08:52PM +0300, Stephane Eranian wrote:
> Some changes to the way invalid MSR accesses are reported by the
> kernel is causing some problems with messages printed on the
> console.
>
> We have seen several cases of ex_handler_msr() printing invalid MSR
> accesses once but the callstack multiple times causing confusion on
> the console.
> The problem here is that another earlier commit (5.13):
>
> a358f40600b3 ("once: implement DO_ONCE_LITE for non-fast-path "do once" functionality")
>
> Modifies all the pr_*_once() calls to always return true claiming
> that no caller is ever checking the return value of the functions.
>
> This is why we are seeing the callstack printed without the
> associated printk() msg.
Extract the ONCE_IF(cond) part into __ONCE_LTE_IF() and use that to
implement DO_ONCE_LITE_IF() and fix the extable code.
Fixes: a358f40600b3 ("once: implement DO_ONCE_LITE for non-fast-path "do once" functionality")
Reported-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Stephane Eranian <eranian@google.com>
Link: https://lkml.kernel.org/r/YqyVFsbviKjVGGZ9@worktop.programming.kicks-ass.net
Diffstat (limited to 'arch/x86/mm/extable.c')
| -rw-r--r-- | arch/x86/mm/extable.c | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c index dba2197c05c3..331310c29349 100644 --- a/arch/x86/mm/extable.c +++ b/arch/x86/mm/extable.c @@ -94,16 +94,18 @@ static bool ex_handler_copy(const struct exception_table_entry *fixup, static bool ex_handler_msr(const struct exception_table_entry *fixup, struct pt_regs *regs, bool wrmsr, bool safe, int reg) { - if (!safe && wrmsr && - pr_warn_once("unchecked MSR access error: WRMSR to 0x%x (tried to write 0x%08x%08x) at rIP: 0x%lx (%pS)\n", - (unsigned int)regs->cx, (unsigned int)regs->dx, - (unsigned int)regs->ax, regs->ip, (void *)regs->ip)) + if (__ONCE_LITE_IF(!safe && wrmsr)) { + pr_warn("unchecked MSR access error: WRMSR to 0x%x (tried to write 0x%08x%08x) at rIP: 0x%lx (%pS)\n", + (unsigned int)regs->cx, (unsigned int)regs->dx, + (unsigned int)regs->ax, regs->ip, (void *)regs->ip); show_stack_regs(regs); + } - if (!safe && !wrmsr && - pr_warn_once("unchecked MSR access error: RDMSR from 0x%x at rIP: 0x%lx (%pS)\n", - (unsigned int)regs->cx, regs->ip, (void *)regs->ip)) + if (__ONCE_LITE_IF(!safe && !wrmsr)) { + pr_warn("unchecked MSR access error: RDMSR from 0x%x at rIP: 0x%lx (%pS)\n", + (unsigned int)regs->cx, regs->ip, (void *)regs->ip); show_stack_regs(regs); + } if (!wrmsr) { /* Pretend that the read succeeded and returned 0. */ |