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Merge branch 'x86-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull misc x86 updates from Ingo Molnar:
 "Misc changes:

   - Enhance #GP fault printouts by distinguishing between canonical and
     non-canonical address faults, and also add KASAN fault decoding.

   - Fix/enhance the x86 NMI handler by putting the duration check into
     a direct function call instead of an irq_work which we know to be
     broken in some cases.

   - Clean up do_general_protection() a bit"

* 'x86-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/nmi: Remove irq_work from the long duration NMI handler
  x86/traps: Cleanup do_general_protection()
  x86/kasan: Print original address on #GP
  x86/dumpstack: Introduce die_addr() for die() with #GP fault address
  x86/traps: Print address on #GP
  x86/insn-eval: Add support for 64-bit kernel mode
This commit is contained in:
Linus Torvalds
2020-01-28 12:28:06 -08:00
parent 6da49d1abd 248ed51048
commit f6170f0afb
10 changed files with 198 additions and 64 deletions
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108
arch/x86/kernel/traps.c
View File

@@ -56,6 +56,8 @@
#include <asm/mpx.h>
#include <asm/vm86.h>
#include <asm/umip.h>
#include <asm/insn.h>
#include <asm/insn-eval.h>
#ifdef CONFIG_X86_64
#include <asm/x86_init.h>
@@ -518,11 +520,57 @@ exit_trap:
do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, error_code, 0, NULL);
}
dotraplinkage void
do_general_protection(struct pt_regs *regs, long error_code)
enum kernel_gp_hint {
GP_NO_HINT,
GP_NON_CANONICAL,
GP_CANONICAL
};
/*
* When an uncaught #GP occurs, try to determine the memory address accessed by
* the instruction and return that address to the caller. Also, try to figure
* out whether any part of the access to that address was non-canonical.
*/
static enum kernel_gp_hint get_kernel_gp_address(struct pt_regs *regs,
unsigned long *addr)
{
const char *desc = "general protection fault";
u8 insn_buf[MAX_INSN_SIZE];
struct insn insn;
if (probe_kernel_read(insn_buf, (void *)regs->ip, MAX_INSN_SIZE))
return GP_NO_HINT;
kernel_insn_init(&insn, insn_buf, MAX_INSN_SIZE);
insn_get_modrm(&insn);
insn_get_sib(&insn);
*addr = (unsigned long)insn_get_addr_ref(&insn, regs);
if (*addr == -1UL)
return GP_NO_HINT;
#ifdef CONFIG_X86_64
/*
* Check that:
* - the operand is not in the kernel half
* - the last byte of the operand is not in the user canonical half
*/
if (*addr < ~__VIRTUAL_MASK &&
*addr + insn.opnd_bytes - 1 > __VIRTUAL_MASK)
return GP_NON_CANONICAL;
#endif
return GP_CANONICAL;
}
#define GPFSTR "general protection fault"
dotraplinkage void do_general_protection(struct pt_regs *regs, long error_code)
{
char desc[sizeof(GPFSTR) + 50 + 2*sizeof(unsigned long) + 1] = GPFSTR;
enum kernel_gp_hint hint = GP_NO_HINT;
struct task_struct *tsk;
unsigned long gp_addr;
int ret;
RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
cond_local_irq_enable(regs);
@@ -539,34 +587,56 @@ do_general_protection(struct pt_regs *regs, long error_code)
}
tsk = current;
if (!user_mode(regs)) {
if (fixup_exception(regs, X86_TRAP_GP, error_code, 0))
return;
if (user_mode(regs)) {
tsk->thread.error_code = error_code;
tsk->thread.trap_nr = X86_TRAP_GP;
/*
* To be potentially processing a kprobe fault and to
* trust the result from kprobe_running(), we have to
* be non-preemptible.
*/
if (!preemptible() && kprobe_running() &&
kprobe_fault_handler(regs, X86_TRAP_GP))
return;
show_signal(tsk, SIGSEGV, "", desc, regs, error_code);
force_sig(SIGSEGV);
if (notify_die(DIE_GPF, desc, regs, error_code,
X86_TRAP_GP, SIGSEGV) != NOTIFY_STOP)
die(desc, regs, error_code);
return;
}
if (fixup_exception(regs, X86_TRAP_GP, error_code, 0))
return;
tsk->thread.error_code = error_code;
tsk->thread.trap_nr = X86_TRAP_GP;
show_signal(tsk, SIGSEGV, "", desc, regs, error_code);
/*
* To be potentially processing a kprobe fault and to trust the result
* from kprobe_running(), we have to be non-preemptible.
*/
if (!preemptible() &&
kprobe_running() &&
kprobe_fault_handler(regs, X86_TRAP_GP))
return;
ret = notify_die(DIE_GPF, desc, regs, error_code, X86_TRAP_GP, SIGSEGV);
if (ret == NOTIFY_STOP)
return;
if (error_code)
snprintf(desc, sizeof(desc), "segment-related " GPFSTR);
else
hint = get_kernel_gp_address(regs, &gp_addr);
if (hint != GP_NO_HINT)
snprintf(desc, sizeof(desc), GPFSTR ", %s 0x%lx",
(hint == GP_NON_CANONICAL) ? "probably for non-canonical address"
: "maybe for address",
gp_addr);
/*
* KASAN is interested only in the non-canonical case, clear it
* otherwise.
*/
if (hint != GP_NON_CANONICAL)
gp_addr = 0;
die_addr(desc, regs, error_code, gp_addr);
force_sig(SIGSEGV);
}
NOKPROBE_SYMBOL(do_general_protection);