[PATCH] PCDP: use early_ioremap/early_iounmap to access pcdp table

From: Greg Pearson
Date: Wed Jul 18 2012 - 18:19:43 EST

The efi_setup_pcdp_console routine 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:

0xffffffff815ffbd4 panic+0x01ca
0xffffffff810535ec do_exit+0x043c
0xffffffff81603847 oops_end+0x00a7
0xffffffff81042859 no_context+0x0119
0xffffffff81042a68 __bad_area_nosemaphore+0x0138
0xffffffff81042b5e bad_area_nosemaphore+0x000e
0xffffffff81606411 do_page_fault+0x0321
0xffffffff81602cb0 page_fault+0x0020
0xffffffff81045fc1 reserve_memtype+0x02a1
0xffffffff810430a3 __ioremap_caller+0x0123
0xffffffff81043402 ioremap_nocache+0x0012
0xffffffff81d53e70 efi_setup_pcdp_console+0x002b
0xffffffff81d1fcc5 setup_arch+0x03a9
0xffffffff81d19b44 start_kernel+0x00d4
0xffffffff81d19341 x86_64_start_reservations+0x012c
0xffffffff81d19449 x86_64_start_kernel+0x00fe

This patch 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@xxxxxx>
drivers/firmware/pcdp.c | 4 ++--
1 files 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)

- iounmap(pcdp);
+ early_iounmap(pcdp, 4096);
return rc;

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