Report machine checks to the kernel
Use a minimally populated logout frame. This is good enough to
handle probing of devices using the kernel's mcheck_expected.
Signed-off-by: Richard Henderson <rth@twiddle.net>
diff --git a/osf.h b/osf.h
index 2794cd7..b849825 100644
--- a/osf.h
+++ b/osf.h
@@ -294,6 +294,7 @@
#define MCHK_K_READ_NXM 0x0200
#define MCHK_K_SYS_HERR 0x0202
+#define MCHK_K_SYS_NOMEM 0x0207
/*
** Machine Check Error Status Summary (MCES) Register Format
diff --git a/pal.S b/pal.S
index 71a9397..64941a8 100644
--- a/pal.S
+++ b/pal.S
@@ -122,7 +122,23 @@
*/
.org 0x0080
Pal_Mchk:
- halt
+ mfpr p6, qemu_exc_addr // Check for palcode mchk
+ blbs p6, MchkFromPal
+ mfpr p0, ptMces // Check for double mchk
+ blbs p0, MchkDouble
+
+ // Since this is QEMU, the only MCHK we raise spontaneously
+ // is for access to non-existent memory.
+ //
+ // ??? With MemTxResult we could perhaps distinguish
+ // between MEMTX_DECODE_ERROR (no memory) and
+ // MEMTX_ERROR (device error), but it's not clear whether
+ // "device error" corresponds to "PCI target abort" or whatnot.
+ // However the main reason to handle mchk at all is to allow
+ // the guest OS to probe for devices, which is just "no memory".
+
+ lda t0, MCHK_K_SYS_NOMEM
+ br MchkLogOut
ENDFN Pal_Mchk
/*
@@ -259,8 +275,8 @@
Pal_Unalign:
mfpr p0, qemu_ps
mfpr p6, qemu_exc_addr
- addq p6, 4, p1 // increment past the faulting insn
blbs p6, MchkBugCheck
+ addq p6, 4, p6 // increment past the faulting insn
STACK_FRAME p0, p1, p2, 1
@@ -1409,7 +1425,8 @@
hw_ret (p0)
0: subq p6, 4, p6 // Get PC of CALL_PAL insn
- br MchkOSBugCheck
+ lda p0, MCHK_K_OS_BUGCHECK
+ br MchkLogOut
ENDFN CallPal_CallSys
ORG_CALL_PAL_UNPRIV(0x84)
@@ -1762,80 +1779,6 @@
.org 0x3000
.text 1
/*
- * PALcode detected processor machine check handler.
- *
- * The PALcode-detected machine check handler loads a code
- * indicating the type of machine check error, loads
- * the System Control Block (SCB) vector for the
- * processor machine check service routine, sets the
- * Machine-Check-In-Progress (MIP) flag in the Machine
- * Check Error Summary register (MCES), and merges
- * with the common machine check flow.
- *
- * If a second processor machine check error condition
- * is detected while the MIP flag is set, the processor
- * is forced into console I/O mode indicating "double
- * error abort encountered" as the reason for the halt.
- *
- * CALLING SEQUENCE:
- *
- * Called when an internal processor error is detected
- * that cannot be successfully corrected by hardware or
- * PALcode.
- *
- * INPUT PARAMETERS:
- *
- * r14 (p6) = Exception address
- *
- * OUTPUT PARAMETERS:
- *
- * ptMchk0 = saved v0
- * ptMchk1 = saved t0
- * ptMchk2 = saved t3
- * ptMchk3 = saved t4
- * ptMchk4 = saved t5
- * ptMchk5 = saved exc_addr
- * ptMisc<47:32> = MCHK code
- * ptMisc<31:16> = SCB vector
- * ptMces<MIP> = Set
- *
- * SIDE EFFECTS:
- *
- * r0 (v0), r1 (t0), and r4..r6 (t3..t5) are saved in
- * PAL temporaries and are available for use as scratch
- * registers by the system specific machine check
- * handler.
- */
-
-MchkBugCheck:
-MchkOSBugCheck:
- halt
-ENDFN MchkBugCheck
-
-/*
- * Common Machine Check Handler
- *
- * INPUT STATE:
- *
- * ptMchk0 Saved v0
- * ptMchk1 Saved t0
- * ptMchk2 Saved t3
- * ptMchk3 Saved t4
- * ptMchk4 Saved t5
- * ptMchk5 Saved exc_addr
- * ptMisc<47:32> MCHK code
- * ptMisc<31:16> SCB vector
- * ptMces<MIP> Set
- *
- * Registers v0, t0, and t3 .. t5 are available for use, in
- * addition to the shadow registers.
- */
-
-MchkCommon:
- halt
-ENDFN MchkCommon
-
-/*
* Build Machine Check Logout Frame
*
* This portion of the machine check handler builds a logout frame
@@ -1848,6 +1791,11 @@
* to the kernel interrupt handler pointed to by the entInt
* operating system entry point.
*
+ * INPUT PARAMETERS:
+ *
+ * r8 (p0) = Machine check reason
+ * r14 (p6) = Exception address
+ *
* OUTPUT PARAMETERS:
*
* a0 (r16) = Machine check entry type
@@ -1855,13 +1803,70 @@
* a2 (r18) = Pointer to logout area
*/
-.macro STORE_IPR which, offset, base
- mfpr v0, \which
- stq_p v0, \offset(\base)
-.endm
+#define MCHK_COMMON_SIZE 24
+#define MCHK_LOGOUT_SIZE 144
MchkLogOut:
- halt
+ mfpr p1, qemu_ps
+
+ // ??? Apparently we skip the insn that caused the mchk.
+ // ??? This is used by the kernel for mcheck_expected.
+ addq p6, 4, p6
+
+ STACK_FRAME p1, p6, p2, 0
+
+ // Restore the real EXC_ADDR for the logout frame.
+ subq p6, 4, p6
+
+ // Locate logout frame
+ br $gp, .+4
+ ldah $gp, 0($gp) !gpdisp!2
+ lda $gp, 0($gp) !gpdisp!2
+ ldah p1, mchk_logout($gp) !gprelhigh
+ lda p1, mchk_logout(p1) !gprellow
+
+ SYS_WHAMI p2
+ mull p2, MCHK_LOGOUT_SIZE, p2
+ addq p2, p1, a2
+
+ // Populate the minimal logout frame
+ lda p2, MCHK_LOGOUT_SIZE
+ stl p2, 0(a2) // size
+ stl $31, 4(a2) // flags
+ lda p1, MCHK_COMMON_SIZE
+ stl p1, 8(a2) // proc_offset
+ stl p2, 12(a2) // sys_offset
+ stl p0, 16(a2) // mchk_code
+ stl $31, 20(a2) // frame_rev
+
+ // EV6 portion, format copied from Linux kernel
+ // although there's not much we can fill in.
+ stq $31, 24(a2) // I_STAT
+ stq $31, 32(a2) // DC_STAT
+ stq $31, 40(a2) // C_ADDR
+ stq $31, 48(a2) // DC1_SYNDROME
+ stq $31, 56(a2) // DC0_SYNDROME
+ stq $31, 64(a2) // C_STAT
+ stq $31, 72(a2) // C_STS
+ stq $31, 80(a2) // MM_STAT
+ stq p6, 88(a2) // EXC_ADDR
+ stq $31, 96(a2) // IER_CM
+ stq $31, 104(a2) // ISUM
+ stq $31, 112(a2) // RESERVED0
+ mfpr p2, qemu_palbr
+ stq p2, 120(a2) // PAL_BASE
+ stq $31, 128(a2) // I_CTL
+ stq $31, 136(a2) // PCTX
+
+ mov IPL_K_MCHK, p1 // Raise IPL
+ mtpr p1, qemu_ps
+
+ mfpr p6, ptEntInt
+ mfpr $gp, ptKgp
+ lda a0, INT_K_MCHK
+ lda a1, 0 // "vector"
+
+ hw_ret (p6)
ENDFN MchkLogOut
MchkDouble:
@@ -1870,6 +1875,7 @@
br Sys_EnterConsole
ENDFN MchkDouble
+MchkBugCheck:
MchkFromPal:
bsr p7, UpdatePCB
lda v0, HLT_K_MCHK_FROM_PAL
@@ -1931,3 +1937,9 @@
.type stack,@object
.size stack,STACK_SIZE * 4
stack: .skip STACK_SIZE * 4
+
+ .globl mchk_logout
+ .type mchk_logout,@object
+ .size mchk_logout,MCHK_LOGOUT_SIZE * 4
+mchk_logout:
+ .skip MCHK_LOGOUT_SIZE * 4
