Commit-ID: a2aa52ab16efbee40ad118ebac4a5e438f5b43ee
Gitweb: https://git.kernel.org/tip/a2aa52ab16efbee40ad118ebac4a5e438f5b43ee
Author: Ingo Molnar <mingo@xxxxxxxxxx>
AuthorDate: Thu, 22 Nov 2018 09:34:03 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Thu, 22 Nov 2018 09:38:13 +0100
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@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/mm/fault.c | 38 +++++++++++++++++++++++---------------
1 file changed, 23 insertions(+), 15 deletions(-)
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index f5efbdba2b6d..2ff25ad33233 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -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;
|