...instead of manually handling the case where error_code=0, e.g. to display "[SUPERVISOR] [READ]" instead of "normal kernel read fault".
This makes the zero case consistent with all other messages and also provides additional information for other error code combinations, e.g. error_code==1 will display "[PROT] [SUPERVISOR] [READ]" instead of simply "[PROT]". Print unique names for the negative cases as opposed to e.g. "[!USER]" to avoid mixups due to users missing a single "!" character, and to be more concise for the !INSTR && !WRITE case. Print "SUPERVISOR" in favor of "KERNEL" to reduce the likelihood that the message is misinterpreted as a generic kernel/software error and to be consistent with the SDM's nomenclature. An alternative to passing a negated error code to err_str_append() would be to expand err_str_append() to take a second string for the negative test, but that approach complicates handling the "[READ]" case, which looks for !INSTR && !WRITE, e.g. it would require an extra call to err_str_append() and logic in err_str_append() to allow null messages for both the positive and negative tests. Printing "[INSTR] [READ]" wouldn't be the end of the world, but a little bit of trickery in the kernel is a relatively small price to pay in exchange for the ability to unequivocally know the access type by reading a single word. Now that all components of the message use the [<code>] format, explicitly state that it's the error *code* that's being printed and group the err_str_append() calls by type so that the resulting print messages are consistent, e.g. the deciphered codes will always be: [PROT] [USER|SUPERVISOR] [WRITE|INSTR|READ] [RSDV] [PK] Cc: Andy Lutomirski <l...@kernel.org> Cc: Borislav Petkov <b...@alien8.de> Cc: Dave Hansen <dave.han...@linux.intel.com> Cc: H. Peter Anvin <h...@zytor.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Rik van Riel <r...@surriel.com> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Yu-cheng Yu <yu-cheng...@intel.com> Cc: linux-kernel@vger.kernel.org Cc: Ingo Molnar <mi...@kernel.org> Signed-off-by: Sean Christopherson <sean.j.christopher...@intel.com> --- arch/x86/mm/fault.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 2ff25ad33233..0b4ce5d2b461 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -609,7 +609,7 @@ static void show_ldttss(const struct desc_ptr *gdt, const char *name, u16 index) */ static void err_str_append(unsigned long error_code, char *buf, unsigned long mask, const char *txt) { - if (error_code & mask) { + if ((error_code & mask) == mask) { if (buf[0]) strcat(buf, " "); strcat(buf, txt); @@ -655,13 +655,16 @@ show_fault_oops(struct pt_regs *regs, unsigned long error_code, unsigned long ad * 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_USER, "[SUPERVISOR]"); + err_str_append(error_code, err_txt, X86_PF_WRITE, "[WRITE]"); err_str_append(error_code, err_txt, X86_PF_INSTR, "[INSTR]"); + err_str_append(~error_code, err_txt, X86_PF_WRITE | X86_PF_INSTR, + "[READ]"); + err_str_append(error_code, err_txt, X86_PF_RSVD, "[RSVD]" ); 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]"); + pr_alert("#PF error code: %s\n", err_txt); if (!(error_code & X86_PF_USER) && user_mode(regs)) { struct desc_ptr idt, gdt; -- 2.19.2