linux-kernel - [ 42/70] pcdp: use early_ioremap/early

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Message-Id: <20120807032802.217296163@decadent.org.uk>
Date:	Tue, 07 Aug 2012 04:28:37 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Greg Pearson <greg.pearson@...com>,
	Khalid Aziz <khalid.aziz@...com>
Subject: [ 42/70] pcdp: use early_ioremap/early_iounmap to access pcdp table

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Greg Pearson <greg.pearson@...com>

commit 6c4088ac3a4d82779903433bcd5f048c58fb1aca upstream.

efi_setup_pcdp_console() is called during boot to parse the HCDP/PCDP
EFI system table and setup an early console for printk output.  The
routine uses ioremap/iounmap to setup access to the HCDP/PCDP table
information.

The call to ioremap is happening early in the boot process which leads
to a panic on x86_64 systems:

    panic+0x01ca
    do_exit+0x043c
    oops_end+0x00a7
    no_context+0x0119
    __bad_area_nosemaphore+0x0138
    bad_area_nosemaphore+0x000e
    do_page_fault+0x0321
    page_fault+0x0020
    reserve_memtype+0x02a1
    __ioremap_caller+0x0123
    ioremap_nocache+0x0012
    efi_setup_pcdp_console+0x002b
    setup_arch+0x03a9
    start_kernel+0x00d4
    x86_64_start_reservations+0x012c
    x86_64_start_kernel+0x00fe

This replaces the calls to ioremap/iounmap in efi_setup_pcdp_console()
with calls to early_ioremap/early_iounmap which can be called during
early boot.

This patch was tested on an x86_64 prototype system which uses the
HCDP/PCDP table for early console setup.

Signed-off-by: Greg Pearson <greg.pearson@...com>
Acked-by: Khalid Aziz <khalid.aziz@...com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/firmware/pcdp.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/pcdp.c b/drivers/firmware/pcdp.c
index 51e0e2d..a330492 100644
--- a/drivers/firmware/pcdp.c
+++ b/drivers/firmware/pcdp.c
@@ -95,7 +95,7 @@ efi_setup_pcdp_console(char *cmdline)
 	if (efi.hcdp == EFI_INVALID_TABLE_ADDR)
 		return -ENODEV;
 
-	pcdp = ioremap(efi.hcdp, 4096);
+	pcdp = early_ioremap(efi.hcdp, 4096);
 	printk(KERN_INFO "PCDP: v%d at 0x%lx\n", pcdp->rev, efi.hcdp);
 
 	if (strstr(cmdline, "console=hcdp")) {
@@ -131,6 +131,6 @@ efi_setup_pcdp_console(char *cmdline)
 	}
 
 out:
-	iounmap(pcdp);
+	early_iounmap(pcdp, 4096);
 	return rc;
 }


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