Re: [PATCH] Treat ISI faults as read faults on classic 32-bit PowerPC
From: Johannes Berg <johannes@sipsolutions.net>
Date: 2007-07-12 09:47:49
On Wed, 2007-07-11 at 20:18 +0200, Segher Boessenkool wrote:
Some old software on ppc32 executes from pages it hasn't marked executable. Since "classic" hardware doesn't distinguish between execute and read accesses, the do_page_fault() code shouldn't either. This makes glibc-2.2 work again on such hardware. Signed-off-by: Segher Boessenkool <redacted> Cc: Scott Wood <redacted> Cc: Johannes Berg <johannes@sipsolutions.net> --- Tested by Scott on 32-bit, glibc-2.2.5 and glibc-2.3.3 (no new failures and problem solved), needs confirmation from Johannes on his glibc-2.4 "---p" testcase. Could use testing on ppc64 and BookE too, for good measure.
Acked-by: Johannes Berg <johannes@sipsolutions.net> I tested this patch and it does fix the problem I was seeing.
quoted hunk
This reverts the previous change and makes the bugfix behave more like the arch/ppc code. arch/powerpc/mm/fault.c | 14 ++++++++++---- 1 files changed, 10 insertions(+), 4 deletions(-)diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index 115b25f..5d7add0 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c@@ -278,14 +278,17 @@ good_area: goto bad_area; #endif /* CONFIG_8xx */ +#ifdef CONFIG_PPC64 if (is_exec) { -#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE)) /* protection fault */ if (error_code & DSISR_PROTFAULT) goto bad_area; if (!(vma->vm_flags & VM_EXEC)) goto bad_area; -#else + } else + /* A read or write, code continues below... */ +#elsif defined(CONFIG_4xx) || defined(CONFIG_BOOKE) + if (is_exec) { pte_t *ptep; pmd_t *pmdp;@@ -310,9 +313,12 @@ good_area: } pte_unmap_unlock(ptep, ptl); } + } else + /* A read or write, code continues below... */ #endif - /* a write */ - } else if (is_write) { + + /* A read or write. Classic PPC32 execute is considered a read. */ + if (is_write) { if (!(vma->vm_flags & VM_WRITE)) goto bad_area; /* a read */
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