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x86/fault: Clean up the page fault oops decoder a bit 

- Make the oops messages a bit less scary (don't mention 'HW errors')

 - Turn 'PROT USER' (which is visually easily confused with PROT_USER)
   into individual bit descriptors: "[PROT] [USER]".
   This also makes "[normal kernel read fault]" more apparent.

 - De-abbreviate variables to make the code easier to read

 - Use vertical alignment where appropriate.

 - Add comment about string size limits and the helper function.

 - Remove unnecessary line breaks.

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ingo Molnar 2018-11-22 09:34:03 +01:00
parent a1a371c468
commit a2aa52ab16
1 changed files with 23 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

38
arch/x86/mm/fault.c
View File

@ -603,10 +603,13 @@ static void show_ldttss(const struct desc_ptr *gdt, const char *name, u16 index)
name, index, addr, (desc.limit0 | (desc.limit1 << 16)));
}
static void errstr(unsigned long ec, char *buf, unsigned long mask,
const char *txt)
/*
* This helper function transforms the #PF error_code bits into
* "[PROT] [USER]" type of descriptive, almost human-readable error strings:
*/
static void err_str_append(unsigned long error_code, char *buf, unsigned long mask, const char *txt)
{
if (ec & mask) {
if (error_code & mask) {
if (buf[0])
strcat(buf, " ");
strcat(buf, txt);
@ -614,10 +617,9 @@ static void errstr(unsigned long ec, char *buf, unsigned long mask,
}
static void
show_fault_oops(struct pt_regs *regs, unsigned long error_code,
unsigned long address)
show_fault_oops(struct pt_regs *regs, unsigned long error_code, unsigned long address)
{
char errtxt[64];
char err_txt[64];
if (!oops_may_print())
return;
@ -646,15 +648,21 @@ show_fault_oops(struct pt_regs *regs, unsigned long error_code,
address < PAGE_SIZE ? "NULL pointer dereference" : "paging request",
(void *)address);
errtxt[0] = 0;
errstr(error_code, errtxt, X86_PF_PROT, "PROT");
errstr(error_code, errtxt, X86_PF_WRITE, "WRITE");
errstr(error_code, errtxt, X86_PF_USER, "USER");
errstr(error_code, errtxt, X86_PF_RSVD, "RSVD");
errstr(error_code, errtxt, X86_PF_INSTR, "INSTR");
errstr(error_code, errtxt, X86_PF_PK, "PK");
pr_alert("HW error: %s\n", error_code ? errtxt :
"normal kernel read fault");
err_txt[0] = 0;
/*
* Note: length of these appended strings including the separation space and the
* zero delimiter must fit into err_txt[].
*/
err_str_append(error_code, err_txt, X86_PF_PROT, "[PROT]" );
err_str_append(error_code, err_txt, X86_PF_WRITE, "[WRITE]");
err_str_append(error_code, err_txt, X86_PF_USER, "[USER]" );
err_str_append(error_code, err_txt, X86_PF_RSVD, "[RSVD]" );
err_str_append(error_code, err_txt, X86_PF_INSTR, "[INSTR]");
err_str_append(error_code, err_txt, X86_PF_PK, "[PK]" );
pr_alert("#PF error: %s\n", error_code ? err_txt : "[normal kernel read fault]");
if (!(error_code & X86_PF_USER) && user_mode(regs)) {
struct desc_ptr idt, gdt;
u16 ldtr, tr;